Silicon Mitigates The Adverse Effect Of Salt Stress On Growth Of Different Plants

Silicon is not generally listed in the list of essential elements, it is considered as one of the significant beneficial nutrient for plant growth. The quantity of Si in soil may vary significantly from 1 % to 45 %. However, Silicon is present in soil in different forms, but plants can easily absorb Silicic acid Si (OH)4 from soil. Silicic acid is usually found in the range of 0.1-0.6 mM in soils. While Si is valuable for plant growth it plays significant role as a physiomechanical barrier in the majority plants.

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Erum Rashid 1 , Muhammad Adnan Shahid 1 , Muhammad Ahsan 2
1 College of Agriculture University of Sargodha, 2 Cholistan Institute of Desert Studies, The
Islamia University of Bahawalpur.

While its facts on cell walls, its active association in a large number of metabolic processes and physiological, is also apparent. Plants deprived of Si often Show poor development and reproduction, but it depends on the type of plant species. For plant growth and production salinity stress is one of the most destructive stressful environments. One possible approach of overcoming the salt-induced deleterious effect on plant growth is the exogenous application of inorganic nutrients and osmo protectants.

By adopting this approach, the supplements of Si to plants subjected to the salt affected soils, because Si has been considered valuable for improving crop tolerance to both abiotic and biotic stresses. According to different investigation the ameliorative role of Si to adverse effects of salinity has been examined in different crops e.g., cucumber, tomato, wheat, rice and barley.

Silicon uptake in the form of uncharged molecule-silicic acid and in plants three different modes of silicon taken up (active, passive, and rejective) may function. In aerial parts of plants silicon distribution is dependent on intensity of transpiration. During the transpiration stream in xylem, silicic acid is transported to leaves and it is accumulated in older tissues. In the shoot, due to the loss of water, silicic acid is concentrated and polymerized

Demonstrating the advantageous effects of silicon appliance in improve salt-induced harmful effects on growth of plant. Decrease in plant photosynthesis under salt stress take place due to closing of stomata that reduced photosynthetic rate leads to reduced plant growth in the majority of plants. Under salinity the closing of stomata that result in decrease in leaf internal CO2 concentration and reduced leaf transpiration rate.


Silicon-induced improvement in plant growth under salt stress may have been due to the important role of Silicon in the improvement of plant water status. Silicon affects plant growth under stressed conditions by affecting a variety of processes including the improvement in plan water status, changes in ultra-structure of leaf organelles, up regulation of plant defense system and mitigation of specific ion effect of salt.

Silicon application to saline medium enhances the photosynthetic activity, chlorophyll content and ribulose bis-phosphate carboxylase (RUBP) activity in leaf cell organelles and also minimizes the salt-induced H2O2 production. Exogenously applied Si improved all those parameters both under non-saline and saline regimes. The other mechanisms for salinity tolerance induced by Si application are; enhanced bioactive gibberellins (GA1 and GA4) contents and reduced jasmonic acid (JA) contents under salinity stress. Si application under saline conditions, detoxifying ROS enhanced under salt stress; as a result chlorophyll increases which lead to the improve (Fv/Fm).

According to different investigations the decrease in value of (Fv/Fm) with salt application and increase in (Fv/Fm) with Si application under abiotic stress might be due to less photoinhibition; where Fv/Fm has a significant positive correlation with A and SPAD values. Salinity stress imposes injurious effects on plant growth, its photosynthetic activity and photochemical efficiency of photosystem II, Silicon application improved all parameters under salt stress by enhancing the A, gs and WUE under salt stress.

Silicon treated plants have higher photochemical efficiency of photosystem II which leads to healthy growth under salt stress conditions. Thus, Si application would be beneficial under salt stress conditions and its beneficial effects should be tested on a larger scale i-e field conditions.

Sustainable management of helicoverpa armigera hubner on sunflower, helianthus annus l.

Twenty diverse genotypes of sunflower helianthus annus L. were exposed to naturally occurring population of H. armigera under preliminary screening trials. Nine out of twenty comprising three each resistant, moderately resistant and susceptible were selected on the basis of egg count and larval infestation. The layout of the experiment was a RCBD with four replications. These selected genotypes were further sown for further experiments. Data for various physico- morphic plant characters was taken at different stages of the growth of the crop.

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The nine genotypes were subject to laboratory analysis to find out the chemical plant characters as part of host plant resistance. Various physico- morphic and plant chemical characters and their correlation with eggs and larval population of the pest was studied. Data regarding temperature, rainfall and humidity was taken during the growing period of the crop. Correlation of weather factors with population build up of H. armigera was also studied. Data regarding egg and larval population, physic- morphic, chemical plant factors and weather factors was subject to multiple regressions to find out the basis of host plant resistance. One comparatively resistant and relatively susceptible genotypes (G53) and (ORB-100) were subject to experimentation for evaluation to different pest management techniques and data were taken before and after the application of treatments on these genotypes.Yield data on the basis of heads of genotypes was taken to know the impact of these treatments on resistant and susceptible genotypes. Genotype (G53) showing potential on all other genotypes, when different set of treatments were applied as part of sustainable pest management methods. Cost benefit ratio of each treatment was compared There was significant difference among the treatments C:B ratio.Our investigation showed potential for developing H. armigera resistant genotypes that would reduce seed feeding injury, prevent yield loss and increase growers profit.

Author: ZAFAR, KHALID

Full Thesis Click Here

Comparative Effects of Salicylic Acid and Calcium Carbide on Some Morphological and Physiological Parameters of Sweet Pepper

Calcium carbide (CaC2) has occupied an important position among different sources of ethylene (C2H4) for improving growth and yield of vegetables. Calcium carbide dependent C2H4 can cause noteworthy improvements in growth, yield and fruit quality of vegetables but its effect on physiological and morphological parameters of vegetables is completely concentration dependent. Under critical environmental conditions, an abrupt release of C2H4 from CaC2 can impede growth and yield of a crop as it initiates leaf, flower and fruit senescence and finally great loss of yields. However, CaC2 dependent released C2H4 can be more constructive and worthwhile for non-conventional production of vegetables if it is applied along with salicylic acid (SA). Salicylic acid not only impedes C2H4 biosynthesis but also plays a crucial role in plant physiology as a stress hormone. As comparative effects of C2H4 released from CaC2 and SA are not thoroughly investigated particularly for production of vegetables with improved quality, therefore, a series of laboratory, pot and field studies were conducted to scrutinize the effectiveness of CaC2 dependent C2H4 with and without application of SA for seed germination, physiological, morphological, yield and quality parameters of sweet pepper. Experiments were conducted in three sections. Section I, II and III consisted of four laboratory, three wire-house/pot and two field experiments, respectively. From first experiment of section-I, polyethylene and paint were selected as the most effective materials for coating CaC2. In second experiment of section-I, it was observed that CaC2 up to 14 mg plate-1 induced early seed germination with 100% germination rate and better seedling growth parameters but application of CaC2 ˃16 mg plate-1 inhibited seed germination and seedling growth parameters of sweet pepper. Similarly, results of third experiment of section-I revealed that SA concentration ≤0.4 mM can be used to improve germination percentage and seedling vigor of sweet pepper. In last experiment of section-I, it was noted that SA alleviated injurious effects of CaC2 with ˃16 mg plate-1 on seed germination and seedling growth parameters. In section-II, data revealed that 20 mg CaC2 kg-1 soil while 0.3 mM SA can be used for maximization of sweet pepper productivity. In last pot trial, effect of CaC2 with and without SA was investigated on growth, yield and fruit quality of sweet pepper under salinity stress. It was observed that detrimental effects of excessive C2H4 from CaC2 on physiology, photosynthesis, growth and yield of sweet pepper were mitigated by the foliar application of SA under saline conditions. On the basis of preliminary trials of section I and II, two field experiments were conducted on two different locations (section-III). Results of both field experiments showed that application of CaC2 along with foliar application of SA improved photosynthetic activity by 7-77%, plant water use and carboxylation efficiency by 10-211%, antioxidant and enzyme activities by 15-53% and finally fruit yield by 5-34% with a significant increase in fertilizer use efficiency compared to that of plants without SA and CaC2 application (control). Additionally, quality parameters related to chemical composition of sweet pepper fruits were also improved by the application of CaC2 with foliar application of SA. These parameters are very much required for improvement in shelf life. In short, results confirm the synergistic role of SA and CaC2 for improving physiology, growth, yield and quality of sweet pepper. Our results suggest that application of 200 mg plant-1 polyethylene coated CaC2 with foliar application 0.1 or 0.3 mM SA is relatively more economically beneficial and effective than application of 200 mg plant-1 polyethylene coated CaC2 without foliar application of SA. Moreover, results also indicated that SA treated plants were tolerated abrupt release of C2H4 from applied CaC2 to a greater extent.

This is an abstract of thesis of Dr.   AHMED, WAZIR for complete thesis please visit http://prr.hec.gov.pk/jspui/handle/123456789//7063

Evaluating the maize productivity under different irrigation and nutrient management practices

Pakistan is water stressed country in which agriculture is major consumer of fresh water supplies. The competition among agriculture, industry and domestic use leads us to acquire alternate source for crop production. However, the quality of alternate water source may result in deterioration of soil in general, particularly crops for human and animal consumption. The objective of present study was to evaluate the use of canal, domestic and municipal wastewater along with press mud application as alternate and improved farm management practices for sustainable food production. To explore the impact of wastewater and press mud on maize, one pot and two field experiments were conducted. The irrigation sources used in the study were municipal wastewater, domestic wastewater and canal water. While the nutrient sources were press mud and inorganic fertilizers. In the pot study different combinations of water qualities and nutrient sources were studied. The results showed that wastewater had adverse effects on the emergence parameters, whereas, press mud mitigated these effects. Seedling growth was good with more plant length and dry weight with municipal wastewater along with press mud followed by the domestic wastewater with press mud. Among the field experiments in first experiment, effect of press mud application under different irrigation waters (municipal wastewater, domestic wastewater and canal water) in comparison with inorganic fertilizers on yield and quality of hybrid maize was studied. In second field experiment, productivity of hybrid maize was tested under different irrigation treatments (T1=canal water, T2=domestic wastewater, T3=municipal wastewater, T4=alternate canal-domestic-canal, T5=alternate canal-municipal-canal, T6=mixed canal & domestic and T7=mixed canal & municipal). All the agronomic traits, plant height (cm), cob diameter, number of grain rows per cob, number of grains per cob, 1000-grain weight (g), biological yield (t ha-1) and grain yield (t ha-1) gave higher values with an increase of 22-27 % in grain yield under municipal wastewater irrigation with press mud in the first experiment over both the years. In second experiment municipal wastewater was best with statistically similar or followed by mixed canal & municipal and alternate canal-municipal-canal regarding the growth and yield components and the highest yield in both the years 2012 and 2013. Municipal wastewater irrigation along with press mud in first field experiment while, municipal wastewater as such or mixed with canal water significantly gave higher seed oil content (%), seed starch content (%) and seed protein content (%) in both the years of study. Seed heavy metal (Cd, Pb, Ni, Cu and Zn) contents were found to be within the limits proposed by international food quality standards in maize under all treatments.

This is an abstract of PhD thesis of  DILDAR KHAN, RANA and taken from hec website you can view complete thesis at http://prr.hec.gov.pk/jspui/handle/123456789/7652

Wheat (Triticum aestivum L.) Allelopathy and its Implications for Weed Management and Rhizosphere Ecology

Studies were carried out to evaluate the allelopathic potential of four hexaploid wheat (Triticum aestivum L.) cultivars (Millat-2011, AARI-2011, Lasani-2008 and Faisalabad-2008) at different growth stages tillering (Z30), anthesis (Z60) and maturity (Z90). The objectives were to ascertain wheat allelopathic potential to suppress emergence and establishment of important grassy and broad-leaved weed species and characterize soil microbial dynamics and enzyme activities under wheat allelopathy. The overall goal was to characterize the variability in wheat allelopathic potential with respect to plant age, cultivar-specific differences, and relevance to soil functional diversity. One field experiment and four wire-house experiments were carried out at the Student Research Area, University of Agriculture, Faisalabad. Field Experiments: The soil at the experimental site belongs to the Lyallpur Soil Series (USDA classification-Aridisol-fine-silty, mixed, hyperthermic Ustalfic, Haplargid; FAO classification -Haplic Yermosols). Wheat cultivars were sown in 4 m × 10 m field plots, and were maintained either weedy or weed free. Fallow plots (without wheat) were used as a control. Trials were laid out in randomized complete block design with four replications. Data were collected on crop growth, weed density and dry biomass, soil chemical and biological properties. Herbage of wheat cultivars was collected at tillering, anthesis and maturity for biochemical analysis. Weed densities were significantly lower in plots sown with wheat than in control plots. Floristic composition of weeds varied significantly among wheat cultivars and between years. A total of seven broad leaf (swine cress, lambsquarters, blue pimpernel, field bind weed, sweet clover, fathen, fumitory and broadleaf dock), three grassy weeds (canarygrass, and bermudagrass) and one sedge (purple nutsedge) belonging to seven distinct families (Poaceae, Chenopodiaceae, Brassicaceae, Primulaceae, Cyperaceae, Fabaceae and Convolvulaceae) were identified. Summed dominance ratios of the weeds were in the order: swine cress > lambsquarters > blue pimpernel > canarygrass > field bind weed > purple nutsedge > sweet clover during 2011-12, and swine cress > blue pimpernel > lambsquarters > canarygrass > field bind weed > purple nutsedge > sweet clover during 2012-13. Summed dominance ratios changed during the growing season due mainly to variation in emergence timing of different weeds; sweet clover emerged at 60 days after sowing (DAS) and broadleaf dock at 75 DAS during 2011-12. Sweet clover and broadleaf dock were identified at 45 and 60 DAS during 2012-13, although during 2011-12, these weeds were absent at these times. Total weed dry biomass at 45 DAS ranged from 0.81-1.39 g m-2 during 2011-12 and 0.45-0.83 g m-2 during 2012-13 in plots sown with wheat compared to 13.02 g m-2 and 2.78 g m-2 in fallow plots, for respective years. At 105 DAS, total weed dry biomass was significantly lower (4.96-14.13 g m-2 and 5.02-6.11 g m-2) in wheat-sown plots than fallow plots (109.38 and 183.24 g m-2) during 2011-12 and 2012-13, respectively. HPLC profile of allelochemicals revealed that wheat herbage contained eight compounds: gallic acid, p-hydroxybenzoic acid, syringic acid, ferulic acid, vanillic acid, protocatechuic acid, p-coumaric acid and benzoic acid. Concentrations of these allelochemicals varied among wheat cultivars and with stage of growth. Concentration of total allelochemicals in 2 wheat cultivars was in order: AARI-2011 > Lasani-2008 > Millat-2008 > Faisalabad-2008, and for growth stages the order was maturity > anthesis > tillering. Higher total phenolic content was recorded in field soil collected at maturity stage of wheat than at tillering and anthesis stages. During the two growing seasons maximum phenolic content (51.73-60.23 mg g-1 soil) were recorded for soil from AARI-2011 plots as compared to fallow (control; 18.09-14.59 mg g-1 soil) respectively. HPLC analysis of wheat-amended rhizosphere soil showed that concentrations of root-exuded, phytotoxic compounds varied with cultivars and the stage of growth of wheat. The overall concentration of allelopathic compounds in rhizosphere soil collected at tillering stage was in order: ferulic acid > benzoic acid > p-hydroxamic acid > gallic acid, at anthesis stage p-hydroxamic acid > ferulic acid > vanillic acid > benzoic acid > p-coumaric acid > syringic acid > protocatechuic acid. However, at maturity the order was p-hydroxamic acid > ferulic acid > benzoic acid > protocatechuic acid > syringic acid > vanillic acid > p-coumaric acid. Maximum invertase, dehydrogenase, cellulase, and phosphatase activities in rhizosphere soil of all wheat cultivars were recorded at anthesis and maturity as compared to tillering. These activities manifested a temporal increase as soil microbial activity, microbial-carbon and -nitrogen increased at the later growth stages (anthesis and maturity). Pot Experiments: Dried herbage was incorporated at 8 g kg-1 soil in plastic pots (10 cm × 26 cm). Control treatment was comprised of soil without herbage. At 7 days after incorporation of herbage, 20 seeds each of canarygrass (Phalaris minor Retz.) and common lambsquarters (Chenopodium album L.) were sown in each pot including control pots (without herbage). Separate experiments were carried out for both the test species. A similar but separate (blank) experiment was set wherein no weed species was grown, to explore the decomposition pattern of wheat herbage and its impact on activities of soil microorganisms and extracellular enzymes. The release of phytotoxic compounds was quantified over a 6-week incubation period. In another set of experiment, leachates were collected from wheat-sown and control pots (soil without wheat). These leachates were used in another set of pot experiment wherein canarygrass and lambsquarters were sown. A separate pot experiment was conducted to appraise the interference potential of wheat cultivars on emergence and seedling growth of test weed species (canarygrass and lambsquarters). For this purpose, wheat cultivars and test species were sown in 1:1 ratio in plastic pots. Control pots contained only one seed type (either of wheat or weed seed). Allelopathic potential against the weed species was evaluated on the basis of seed germination and seedling growth; and biochemical and antioxidant enzyme analyses were carried out to understand the basis for possible allelopathic interference. To have an insight into rhizosphere ecology analyses of microbial abundance (population of bacteria and fungi, soil-microbial-biomass-carbon and -nitrogen) and analysis of extracellular enzymes (cellulase, urease, invertase, dehydrogenase, phosphatase, and polyphenol oxidase) were performed. All pot experiments were conducted using completely randomized designs with four replications. Experiment-I A: Incorporation of herbage collected at anthesis and maturity stages of wheat cultivars AARI-2011 and Lasani-2008 prolonged mean emergence time of canarygrass to greater than the control. Final emergence percentage dropped by 13-31% in response to soil incorporation of herbage collected at different growth stages. Maximum suppression of shoot (33-51% and 28-53%) and root (34-52% and 28-54%) lengths and seedling dry biomass (66- 3 88% and 58-86%) of canarygrass over control was also observed with the aforementioned treatment combinations. Total chlorophyll content declined where herbage collected at anthesis and maturity stages of all wheat cultivars was incorporated into soil, but phenolic content was higher than with the control where herbage collected at tillering was applied. Activities of enzyme antioxidants also varied among wheat cultivars, and declined with the incorporation of herbage collected at anthesis and maturity but were enhanced by tillering stage herbage compared with the control. Wheat herbage induced lipid peroxidation in canarygrass seedling. Higher malondialdehyde (MDA) content (1.28 and
1.14 nmol g-1 FW) was observed by the incorporation of herbage of wheat cultivars AARI-2011 and Lasani-2008, respectively. Anthesis- and maturity-stage herbage of AARI-2011 and Lasani-2008 was more phytotoxic than that of Millat-2011 and Faisalabad-2008. Moreover, herbage of all wheat cultivars collected at tillering stage had a stimulatory effect on emergence, seedling growth and biochemical attributes of canarygrass. Experiment-I B: Mean emergence time (MET) of lambsquarters was prolonged over control with herbage of all wheat cultivars collected at anthesis and maturity stages. Final emergence percentage dropped by 3-17% in response to herbage collected at different growth stages. Maximum suppression of shoot (45 and 78%) and root (60 and 90%) lengths, and seedling dry biomass (65 and 96%) of lambsquarters over control was recorded in response to amendment with herbage collected at anthesis and maturity stages of wheat. Total chlorophyll content declined to lower than the control in response to incorporation of herbage from all wheat cultivars collected at anthesis and maturity stages. Phenolic content, on the other hand, increased. Activities of enzyme antioxidants extracted from lambsquarters varied with wheat cultivar and declined with the incorporation of herbage collected at tillering, anthesis and maturity stages. Wheat herbage induced lipid peroxidation in lambsquarters seedlings, and higher MDA content (0.56 and 0.77 nmol g-1 FW) was observed with the incorporation of herbage collected at anthesis and maturity stages, respectively. Herbage of Millat-2011, AARI-2011 and Lasani-2008 collected at anthesis and maturity stages was more phytotoxic than that of Faisalabad-2008 collected at the same stages. Moreover, herbage of all wheat cultivars collected at tillering stage only mildly inhibited emergence, seedling growth and biochemical attributes of lambsquarters. Experiment-II: Wheat herbage amendment increased soil pH, phenolic content, organic-carbon and -nitrogen content compared to nonamended soil. Total carbon, total nitrogen, total soluble phenolic content, and saturated and unsaturated fatty acids were significantly different in soil amended with wheat herbage collected different growth stages. Maximum total carbon and nitrogen were observed for herbage collected at anthesis and maturity stages compared to herbage collected at tillering. Both of the organic-carbon and -matter significantly increased with progression in incubation time where wheat herbage was incorporated into soil; whereas these soil components declined in nonamended soil. Analysis of herbage-amended-soil during different incubation periods showed that microbial population, and activities of extracellular enzymes (urease, invertase, dehydrogenase, and phosphatase) increase during the six-week incubation period. All these activities were higher in the soil amended with herbage of Millat-2011 and AARI-2011 collected at anthesis and maturity stages than with those of Lasani-2008 and Faisalabad-2008 collected at same growth stages. The concentrations of phytotoxic compounds from decomposing wheat 4 herbage also differed with cultivar, stage of growth at which herbage was collected, and the incubation period. HPLC analysis of soil extracts from soil amended with wheat herbage showed that they contained eight phytotoxic compounds gallic acid, p-hydroxybenzoic acid, syringic acid, ferulic acid, p-coumaric acid, vanillic acid, protocatechuic acid and benzoic acid the concentrations of which were dependent on growth stage and the duration of herbage incubation in the soil. Experiment-III A & B: Application of leachates from herbage-amended soil affected emergence dynamics of both canarygrass and lambsquarters seedlings in a cultivar-dependent manner compared to the control. Leachate from AARI-2011-amended soil significantly reduced the final emergence (14 and 23%) and seedling dry biomass (36 and 64%) of both canarygrass and lambsquarters, respectively, compared to the control. Application of leachates from soil amended with AARI-2011 and Lasani-2008 herbage significantly reduced the protein content of canarygrass (48-53%) and lambsquarters (90-92%). Catalase and peroxidase activities of canarygrass (272% and 45%) and lambsquarters (83 and 82%) also declined under the influence of leachates from AARI-2011-amended soil compared to the control. Reduced superoxide dismutase activities were recorded with the application of leachates from soils amended with all wheat cultivars compared to control for both weed species. Application of root leachates significantly influenced the populations of soil bacteria and fungi compared to control. Maximum increases in microbial populations and soil enzymatic activities were recorded under the influence of root leachates from AARI-2011-amended soil in both canarygrass and lambsquarters sown pots. Experiment-IVA & B: None of the wheat cultivars showed reduction in emergence and seedling growth in response to interference by canarygrass and lambsquarters when grown in a 1:1 ratio. Emergence index and final emergence of canarygrass were inhibited by 25 and 21%, respectively, when grown with wheat cultivars. Similar results were recorded for lambsquarters. Reduction in shoot length (39%) and seedling dry biomass (79%) of canarygrass occurred due to interference of wheat cultivars compared with the control. Shoot and root lengths of lambsquarters were significantly reduced (43% and 48%, respectively) compared to the control. Interference of wheat cultivars reduced the seedling dry biomass of lambsquarters by 49%. The highest reduction was recorded with AARI-2011. It can be concluded from the results of the present investigations that wheat demonstrated allelopathic potential that varied with cultivar as well as growth stage. Wheat cultivars AARI-2011, Millat-2011 and Lasani-2008 were more allelopathic at anthesis and maturity stages than at tillering stage. Wheat cultivars and the stage of crop growth resulted in modifications in rhizosphere microbial communities that may be due to the release of allelochemicals during the herbage decomposition process. Phenolic content of herbage increased with advancement in stage of wheat growth, which was also evident in soil amended with such herbage. The information generated provides evidence in support of soil incorporation of herbage of specific wheat cultivars to manage weeds of economic significance in wheat-based cropping systems and for increasing soil quality.

This is abstract of PhD thesis of FARHENA for complete thesis visit http://prr.hec.gov.pk/jspui/handle/123456789/7061

Forage productivity, silage characteristics and digestion kinetics of cereal-legumes mixture under different tillage systems and varying row and seed ratios

In many parts of world intercropping of legumes and non-legumes is considered very important practice. When legumes is grown in mixture with non- legumes they contribute well to non- legume crop for nitrogen. To investigate the forage potential and characteristics of silage of cereal-legume intercropping under various planting ratios and different tillage systems the study was conducted during spring season 2013 and 2014, which was comprised of two experiments each experiment consist of three parts Field trial, Laboratory scale silage and In situ digestion kinetics trial. Field trials were conducted at Agronomic Research Area, University of Agriculture Faisalabad, Pakistan. The tillage practices and row ratios in first experiment were minimum tillage; one ploughing with cultivator followed by planking; deep tillage; one ploughing with chisel plough + one ploughing with cultivator followed by planking; and row ratios sole sorghum, sole millet, sole sesbania, sorghum + sesbania(1:1), sorghum + sesbania(1:2), sorghum + sesbania(2:1), millet + sesbania(1:1), millet + sesbania(1:2), millet + sesbania(2:1). The tillage practices and seed ratios for second experiment were include minimum tillage; one ploughing with cultivator followed by planking; deep tillage; one ploughing with chisel plough + one ploughing with cultivator followed by planking; and seed ratios sole maize, sole cowpea, maize + cowpea (60% + 40%), maize + cowpea (70% + 30%), maize + cowpea (80% + 20%). Field trials of both experiments were laid out in randomized complete block design having split plot arrangement with three replications. In both experiments tillage practices significantly affected the growth and yield of forage. Results showed that the deep tillage practice significantly increased the emergence count, plant height, number of leaves per plant fresh and dry weight per plant, fresh forage yield and dry matter yield while it has little effect on the quality of cereal-legume mixed forage. In both experiments intercropping ratios significantly affected the growth, yield and quality of forage. In first experiment cereals sown in mixture with sesbania with different row ratios, sorghum sown alone produced significantly higher fresh forage yield and dry matter yield than all other row ratios of cereals in combination with sesbania. Minimum fresh forage yield and dry matter yield was observed in sole sesbania during both years of study. All cereal + sesbania mixture produced higher crude protein percentage, ash contents and lower crude fiber percentage than sole cereals. Land equivalent ratio (LER) was highest in sorghum + sesbania (1:1) row ratio. In second experiment maize sown in mixture with cowpea with different seed ratios, maize sown alone produced significantly higher fresh forage yield and dry matter yield than all other seed ratios of maize in combination with cowpea. Minimum fresh forage yield and dry matter yield was observed in sole cowpea during both years of study. All maize + cowpea mixture produced higher crude protein percentage, ash contents and lower crude fiber percentage than sole maize. Land equivalent ratio was highest in maize + cowpea (70% + 30%) seed ratio. Silage quality increased with increased in concentration of legumes crop in forage mixture as compared to sole cereal crop silage which resulted in an increase in dry matter (DM) and neutral detergent fiber (NDF) degradability in rumen of cannulated buffalo bulls.

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Gwadar Needs Research on Water

By Tassadduq Rasool*, Mujahid Ali**

*Agronomy, **Horticulture; University of Agriculture Faisalabad

The port city of Gwadar has got more attention after being a part of China-CPEC program. This Sino-Pak project is expected to give unprecedented economic benefits to the region. The real estate personal skyline its future as a Dubai like city and Govt. is committed to making it a modern port city. However, despite many positive initiatives, still, it has an alarming issue and ground realities are quite different. Gwadar port city was hit by an acute water shortage this year when the main supply source “Akara Kaur Dam” dried out, that is located 25 km from Gwadar city. A team of researchers led by Shahid Naseem from the University of Karachi assessed water quality of Akara Dam and found its composition suitable for use as fresh water. However, it is influenced by calcium sulfate dissolution and might deteriorate its quality in near future. Water is a versatile resource for a human being that fulfills its domestic, agricultural and industrial needs. About 100000 local residents of Gwadar need access to this basic life facility. They are dependent on costly portable water supplied by tankers from a distance of 80 km. Gwadar, being projected a well growing port city, will have its water requirement increased in the coming days. According to Leonardo da Vinci “Water is driving force of all nature”. The government has prioritized to establish new desalinization plants under CPEC-project, to make fresh water available for the better future of this city. These plants will supply 5 million gallons of water per day at a rate of 80 cents per gallon. These plants will be inaugurated in January-2018 and people will have access to clean drinkable water. The development of the city is strongly correlated to access of basic life facilities. We need research that should prioritize the use of water according to its quality. Moreover, domestic use can be cut down by developing water conservation tools by domestic engineering. The ocean can be a good resource for an endless supply of drinkable water. The research should be based on desalinization of seawater, use of brackish groundwater and reuse of wastewater. The most prominent techniques for desalinization are thermal desalinization adopted in the Persian Gulf and pretty much common is “the reverse osmosis” everywhere in the world. Water is taken through intake pipes from the ocean, filtered from largely sized contaminants or sea living creatures and passed through pressurized reverse osmosis system, to screen salts through membranes. The only issue is that, membranes pores are choked by microbial colonization and it makes it costly to periodically clean the membranes. Recently a breakthrough in the membrane technology has been made, that utilizes the lava stone to capture microbes, before they reach the membranes. There are several other possible technologies of future like “Spin cycle” developed by Palo Alto Research Center (PARC) in California; membrane screening under low hydraulic pressure, forward osmosis, and microbial fuel cell etc. Another cost-effective technology is “Biosantizer” developed by Dr. Uday S. Bhawalkar in INDIA to treat waste-water. This technique is an ecological-based and has shown sustainability for the last 12 years. Recently a group of scientists in Australia has developed a salt tolerant wheat by incorporation of gene “TmHKT1;5-A”; a big breakthrough in the food production in the salt-affected areas. Moreover, Israel is meeting 60% of its domestic water needs by desalinization of water. The research on efficient use of water in homes has cut down to halves than actual needs. They have prioritized the research on drip irrigation, water treatment and desalinization. The major driving force behind all this effort is that, Israel is in one of the driest regions and has faced the challenge of severe drought in 2008. So, turning ocean into drinking water is not out of future now. The Sorek desalinization plant in Israel is the largest facility in the world, working on reverse-osmosis principle. It supplies 1.5 million people with drinkable water. There would be seven desalinization plants working by 2020, in Los Angeles and Orange counties of USA. Another important facility is in Carlsbad desal, that is supplying 50 million gallons of water per day to San Diego, USA.  The cost estimates show that fresh drinkable water has no alternative. The cities near the ocean have limited access to fresh water, and they meet their need either from imported supply or from desalinization. According to estimates, desalinization costs might range from Rs. 209000 to Rs. 221000, per 326000 gallons of water (Costs converted from Dollars to Pak currency). There are many disasters due to water shortages. Recently in Syria, more than a million farmers made strikes in Aleppo because drought affected severely the agriculture and wells eventually dried out due to extensive pumping deeps in the water table. The efficient household water use can be a game changer as well. Israel recaptures the 86 % of the water going down into drains and utilize it for agriculture. Another most efficient country is Spain that has the capability to capture almost 18% for utilization. The modern world has developed the efficient toilet and shower systems, and innovative treatment systems that make them reusable. Water conservation has become essential even in areas of abundant water supply. Overall, I can say, it’s not easy to make all waters drinkable especially from the sea that contains salts within a range of 30000-40000 ppm as compared to freshwater 1000 ppm. Still, there are a lot of option and a hope. The desalinization era has been started by Israel.

The issues of in situ conservation of crop genetic resources

Domesticated plants have been fundamentally altered from their wild relatives; these species have been moved into and adapted to new environments; they have become dependent on the tiller’s hand; and they have been reshaped to meet human needs and wants. Modern crops are the result of thousands of years of these evolutionary processes. Like all biologicalnevolution, crop evolution involves two fundamental processes: the creation of diversity and selection (Harris and Hillman 1989). Crop evolution is distinguished by two types of selection: one natural and another artificial or conscious. These evolutionary processes must continue in order for agriculture, a living and evolving system, to remain viable. Therefore, an essential criterion of crop evolution is the availability of genetic diversity. Crop evolution has been altered by our enhanced ability to produce, locate, and access genetic material, but this has not changed its fundamental nature.

Both farmers and scientists have relied on the store of genetic diversity present in crop plants that has been accumulated by hundreds of generations who have observed, selected, multiplied, traded, and kept variants of crop plants. The result is a legacy of genetic resources that, today, feeds billions of humans.

Genetic diversity is important both to individual farmers and farming communities and to agriculture in general. Individual farmers value diversity within and between their crops because of heterogeneous soils and production conditions, risk factors, market demand, consumption, and uses of different products from an individual crop species (Bellon 1996). Thus a wheat farmer in Turkey may have different types of wheat for hillside or valley bottom areas, for irrigated and rain-fed parcels, for homemade bread and for urban grain markets, for straw and animal feed (Brush and Meng 1998). Moreover, farmers usually rely on diversity of other farms and communities to provide new seed when crops fail or seed is lost or to renew seed that no longer meets the farmer’s criteria for good seed (Louette et al. 1997). The need for diversity at both the farm and regional levels has resulted in a vast store of genetic diversity in crops, a store passed down from earlier generations and maintained for the future. In regions where a crop’s evolution has the longest record, where the crop was originally domesticated, and where its diversity is greatest, the local store of genetic diversity in farming communities is also a store of genetic resources for that crop, an invaluable resource for farmers, scientists, and consumers elsewhere (Hawkes 1983).

Unfortunately, this legacy is imperiled by the very conditions it helped to create (Wilkes 1995). Record numbers of humans, agricultural science and technology, and economic integration of the world’s many diverse cultures threaten to destroy this legacy, as modern crop varieties and commercial farming diffuse into every agricultural system. A result of these changes is that diversity on individual farms and across wide regions is threatened by modern crop varieties that have been bred for broad adaptation, resistance to disease and other risk factors, ability to better use water and fertilizer, and higher yields. This threat is evidenced by the fact that agricultural development in Europe, North America, and many less developed countries has been accompanied by the replacement of diverse, local populations of crops with a handful of modern varieties.

The importance of crop genetic resources and threats to them has led to the creation of conservation programs to preserve crop resources for future generations. One type of crop genetic conservation is ex situ — maintenance of genetic resources in gene banks, botanical gardens, and agricultural research stations (Plucknett et al. 1987). Another type is in situ —maintenance of genetic resources on-farm or in natural habitats (Brush 1991; Maxtel et al. 1997a). In actuality, two types of in situ conservation can be distinguished. First, in situ conservation refers to the persistence of genetic resources in their natural habitats, including areas where everyday practices of farmers maintain genetic diversity on their farms. This type is a historic phenomenon, but it is now especially visible in regions where farmers maintain local, diverse crop varieties (landraces), even though modern, broadly adapted, or higher yielding varieties are available.

Second, in situ conservation refers to specific projects and programs to support and promote the maintenance of crop diversity, sponsored by national governments, international programs, and private organizations. In situ conservation programs may draw on the existence and experience of the first type, but they are designed to influence farmers in the direction of maintaining local crops by employing techniques that may not be local. This type of conservation faces daunting tasks. It must cope with continual social, technological, and biological change while preserving the critical elements of crop evolution — genetic diversity, farmer knowledge and selection, and exchange of crop varieties.

In situ conservation practices and projects in agriculture theoretically can concern the wide spectrum of genetic resources relating to crops, from wild and weedy relatives of crop species to the infraspecific diversity within crop species (Maxted et al. 1997b). The exemplified by heterogeneous crop populations known as landraces. These are named, farmer varieties that usually have a reduced geographic range, are often diverse within particular types, and are adapted to local conditions (Brush1995; Harlan 1995). One reason for our focus on diversity within cultivated crops is that science of in situ conservation of cultivated resources is relatively less developed than the science of conserving wild resources such as wild and weedy crop relatives. Another reason is that in situ conservation of cultivated plants requires novel approaches, while in situ conservation of wild crop relatives can draw on theories and methods developed for conserving many different species in their natural habitats. Finally, focusing on variation within cultivated species is warranted by the fact that this type of diversity is arguably the most important one for the future viability of agricultural evolution, as it has been in the past.

The successful planning and implementation of projects for on-farm (in situ) conservation of crop genetic resources require us to answer four questions.

First, why undertake this type of conservation, especially when investments are made for ex situ conservation? Second, what scope is necessary or appropriate for in situ conservation of crop germplasm? Third, how can agricultural agencies and organizations promote this form of conservation? Finally, what legal and institutional questions pertain to on-farm conservation of genetic resources? The answers to these questions come from different fields of science, for example, population biology and social science, and from law and politics. Moreover, the answers to these questions seldom are definitive. More important than definitive answers is the ability to seek answers, because new answers will be needed for different times, conditions, crops, and societies.

The purpose of this and other chapters in this book is not to answer these four questions but rather to offer guideposts and a context for finding answers in specific regions and for specific crops and cropping systems.

Why in situ conservation?

The invention and development of agriculture was accomplished independently in several places in the world, but within a relatively narrow time period following the end of the Pleistocene period — 8,000 to 10,000 years before the present (Harris and Hillman 1989). Why agriculture arose during this limited time period and only in a few places, and exactly how wild plants were identified, manipulated, and managed for domestication remain mysteries. Although the origins and processes of crop domestication are obscure, its consequences are well known and thoroughly documented the creation of an entirely new way of life and eventual rise of urban civilization with all of its wonders and woes. Since the time of domestication, a progression of changes has occurred in farming systems and social systems associated with agriculture. Greater numbers of people than ever before in human history are dependent on a smaller number of crop species; a handful of “mega-crops” have supplanted locally important crops and now feed most of the world’s population (Wilkes 1995). The reduction in interspecies diversity of food plants continues the trend of exercising ever greater control over nature and the production process, a trend also supported by the increased use of manufactured inputs in crop production.

Individual social and production systems have been gradually but inexorably integrated into a single, interconnected world system of economic, cultural, and technology exchange, and this integration threatens genetic diversity of crops as much as population increase and modern technology.

Until recently, most crop production was intended for local consumption, and it relied mostly on local resources of energy and crop germplasm. Today, however, exceedingly few farming systems function in isolation from  markets, national and international political influence, and flows of capital, energy, and technology. Although most farmers still produce their own food, they also sell an appreciable amount into local and national markets. The use of non-local technology and inputs, such as fertilizers, pesticides, and mechanization, is ubiquitous. An increasingly important part of the flow of technological goods to farmers is improved crop varieties, selected from outstanding farmer varieties, developed and released by public crop improvement programs, or sold by private seed companies.

The economic, political, and technological integration of farming systems is generally seen as a positive step that enables development — increased production, income, and well-being (Hayami and Ruttan 1985). Nevertheless, this integration has several negative impacts. Farmers relinquish personal and local control of the production system as they become subject to market and political systems that are not always stable or positive for particular locations or commodities (Chambers 1983; Cernea 1985). Communities and farming systems may become more stratified economically. Increasingly uniform crops may be more vulnerable to pests and diseases. Local knowledge and crop diversity may be lost because of the diffusion of improved, exotic technology.

These negative impacts may be ameliorated by policy and technological means, although the knowledge and ability to manage the negative impacts of change are often underdeveloped. Nevertheless, it is important to note that lack of socioeconomic integration also carries potentially serious negative impacts, especially given population growth.

Cultivar diversity in association with wild or ancestral crop species is linked to crop domestication and, most importantly, a broad base of genetic resources that may be useful for crop improvement. The loss of crop varieties from centers of diversity causes genetic erosion or a loss of genetic resources — a negative consequence of agricultural development. Natural historians and biologists have long recognized that particular areas harbored unusually  diverse and rich stores of crop germplasm (Harris 1989). One contribution of N. I. Vavilov (1926) was to perceive that these stores were important resources for crop improvement. Shortly after Vavilov’s observation, it was noted that these concentrations of crop germplasm were vulnerable to loss, as technological and economic change occur (Harlan and Martini 1936). Once the stores of crop germplasm were identified, a worldwide effort was initiated, first to sample and then to conserve the genetic diversity of major food staples (e.g., rice, wheat, maize, potato, cassava, sorghum, millet, barley, common bean, soybean). The conservation effort focused on preserving crop germplasm that is held in the thousands of distinct crop varieties or cultivars. By 1980, a large portion of the estimated diversity of major staples had been collected for preservation in ex situ facilities — gene banks, botanical gardens, and working collections of crop scientists. During the establishment of the current gene conservation effort (1970-1980), in situ conservation was perceived as a possible alternative strategy for conserving crop germplasm, yet it was dismissed for several reasons (Frankel 1970). Most importantly, it was assumed that progress in achieving economic development in diverse agricultural systems inevitably requires the replacement of local crop populations with improved ones.

Because genetic diversity in crops is associated with traditional agricultural practices, it is also linked to underdevelopment, low production, and poverty.

The positive relationship between crop diversity and poverty is seemingly confirmed by the fact that agricultural development in many places and at different times occurred with the replacement of local and diverse crops, for example, in the hybrid maize revolution in U.S. agriculture between 1920 and 1950 (Cochrane 1993). A corollary of the relationship between diversity and poverty is that conserving traditional crops and their genetic diversity on-farm is tantamount to trying to stop agricultural development. Another reason for rejecting in situ conservation is the assumption that farmers who grow traditional crop varieties would require a direct monetary subsidy to continue this practice once improved varieties become available. Such subsidies are not only expensive but also unreliable and difficult to manage for any length of time. Finally, crop scientists who promoted conservation were not interested in conservation alone but also in using genetic resources for crop improvement. As long as breeders’ work is confined to experiment stations and laboratories, genetic resources that remain in farmers’ fields are not directly useful for crop improvement. Several decades of collection and gene bank storage of crop genetic resources and research on agricultural change under modern conditions have changed the views that led to the dismissal of in situ conservation in favor of ex situ methods (Maxted et al. 1997a). One important shift in attitudes is the view that in situ and ex situ methods are no longer perceived as exclusive alternatives to each other. Today, they are seen as complementary approaches rather than as rivals. There is recognition that these methods address different aspects of genetic resources, and neither alone is sufficient to conserve the total range of genetic resources that exist.

 

How we can make crops survive without water

How we can make crops survive without water, Farrant discusses the work she’s doing with resurrection plants and their ability to exist and thrive in a warmer and drier world. Her central idea is water and the ways that different plants require water to survive. As the world’s population grows and the effects of climate change come into sharper relief, we’ll have to feed more people using less arable land. Molecular biologist Jill Farrant studies a rare phenomenon that may help: “resurrection plants” — super-resilient plants that seemingly come back from the dead. Could they hold promise for growing food in our coming hotter, drier world?