Interaction between nutrient and plant diseases

Interactions between plants, nutrients, and disease pathogens are very complex and not completely understood. Nutrition, although frequently unrecognized, has always been a primary component of disease control. Plants suffering a nutrient stress will be less vigorous and more susceptible to a variety of diseases. The severity of most diseases can be reduced and the chemical, biological or genetic control of many plant pathogens can be enhanced by proper nutrition.
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Elements Relation with diseases
Nitrogen Excessive N enhanced tissue susceptibility to blast disease N suppresses fungal disease and feeding intensity of sucking insects.
  
Phosphorus
  
P lowers the susceptibility to fungal attacks because it is a component of phospholipids in cellular membranes.
Potassium K application reduces insect attacks and fungal and nematode infections, because is has a role in cellular functions and thick- cuticle development.
Calcium Ca as a component of calcium pectate in the middle lamella, its levels were related to lower susceptibility of leaves to fungus.
Sulphur S used as fungicide to control and suppress fungal diseases 
Accumulation of S in xylem vessel invading fungal pathogen.
Zinc Zn prevents leakage of sugar onto the plant surfaces, which can enhance the invasion of fungus and bacteria.
Copper Cu fertilization decreases the severity of the Pyricularia oryzae on rice due to its role as a component of polyphenol oxidase Copper has the ability to denature the spores and conidia of fungus.
Silicon Diseases such as blast, brown spot and sheath blight can be ex- tremely threatening to rice cultivation if Si is deficient in soil. Silicon has physiological roles in disease resistance.

Essential nutrient elements besides their growth enhancing and yield maximizing roles may also have secondary effect on survival and virulence of pathogens or the tolerance of the host plant to the disease. Deficiency of nutrients has often been regarded as predisposing factors in plant susceptibility to many plant diseases. Application of nutrient elements has shown reduction in disease incidence in rice plant.

Element Diseases Causal organism
K Leaf spot Helminthosporium spp.
Brown spot Cochliobolus miyabeanus
Sheath blight Rhizoctonia solani
Stem rot Sclerotium oryzae
Brown spot Ophiobolus miyabeanus
Blast Pyricularia grisea
Stem rot Sclerotium oryzae
Bacterial leaf blight Xanthomonas oryzae pv. oryzae
Cu 
 
Mn
Blast Pyricularia grisea
Blast Pyricularia grisea
  
 
Zn
 
 
Si
Leaf spot Alternaria spp.
Leaf spot Cochliobolus miyabeanus
Stem/sheath blight Rhizoctonia solani
Blast Pyricularia grisea
Brown spot Cochliobolus miyabeanus

Functions of essential nutrient elements

Elements Functions
Nitrogen (N) It is integral part of chlorophyll. It promotes rapid growth, increase plant height and tiller number. It plays an impor tant role in synthesis of proteins, enzymes, hormones, vita mins, alkaloids, nucleic acids (DNA, RNA) etc.
Phosphorus (P) It plays central role in energy transfer and protein metabo- lism. It is a constituent of sugar phosphates, nucleotides, nucleic acids, co-enzymes and phospho-lipids.
Potassium (K) It helps in osmotic and ionic regulation and is required as a co-factor or activator for 40 or more enzymes. It imparts disease and drought resistance.
Calcium (Ca) It is involved in cell division and plays a major role in the maintenance of membrane integrity. It is a constituent of cell wall as calcium pectate.
Magnesium (Mg) It is central part of chlorophyll and it is required in several enzymes involved in phosphate transfer. It is structural com- ponent of ribosomes.
Sulfur (S) Somewhat like phosphorus, it is involved in plant cell en- ergetics. It plays an important role in plant lipid synthesis and amino acids.
Zinc (Zn) It is an essential component of several enzyme systems (de- hydrogenases, proteinases and peptidases including carbonic anhydrase and alcohol dehydrogenase).
Iron  (Fe) As a constituent of various enzymes (cytochrome, catalase, dipeptides etc.), iron plays the part of a vital catalyst in the plant. It is a key element in various redox reaction of respi- ration and  photosynthesis.
Manganese (Mn) It is involved in the O  evolving system of photosynthesis
2
and it is a constituent of decarboxylases, kinases, oxidases etc. and hence, essential for respiration, formation of chlo- rophyll and reduction in nitrates.
Copper (Cu) Acting as a component of metalloenzymes, regulating some enzymatic actions, and catalyzing oxidation reactions; Play ing a role in: i) nitrogen, protein and hormone metabolism; ii) photosynthesis and respiration.
Elements Functions
Boron (B) It is essential for development and growth of new cells in plant meristem. It is necessary for the germination of pol- len, formation of flowers and for the absorption of cations.
Molybdenum (Mo) It’s function in rice plants is limited to the reduction of nitrate to nitrite. It is a component of nitrogenase, nitrate reductase, sulphate oxidase and xanthine hydrogenase en- zymes .
Chlorine (Cl) Essential for photosynthesis and as an activator of enzymes involved in splitting of water. Associated with osmo-regula- tion of plants growing in saline soils.

Recognition of nature of nutrients deficiency symptoms

The symptoms can be of chlorotic, necrotic or deformed one. Chlorosis is characterized by yellowing: generalized over whole plant (uniform yellowing- N and S); localized over individual leaves or isolated between some leaf veins (interveinal chlorosis). Necrosis is characterized by death of plant tissue sometimes in spots (dead spots). The dead spots appear particularly on margins and tips

Research Looks at Natural Fertilizer for Greener Agriculture, Cleaner Water

Fertilizer is made of nutrients like nitrogen and phosphorus. Chemical fertilizers require huge amounts of energy to produce. But there are other, natural and more readily available sources.

The University of Michigan, with support from the National Science Foundation, is working at making our water cleaner, and our agriculture more sustainable, by capturing one of those sources, rather than flushing it down the toilet.

On a hot summer afternoon near Brattleboro, Vermont, farmer Dean Hamilton has fired up his tractor and is fertilizing his hay field — with human urine.

It takes a bit of time to get used to, says environmental engineer Nancy Love.

“I’ve been surprised at how many people actually get beyond the giggle factor pretty quickly,” she said, “and are willing to listen.”

Fine-tuning the recycling

Rich Earth Institute, a nonprofit, is working with Love and her team. Abraham Noe-Hays says they are fine-tuning new methods to recycle urine into fertilizer.

“There’s a great quote by Buckminster Fuller about how pollution is nothing but the resources that we’re not harvesting, and that we allow them to disperse because we’ve been ignorant of their value,” he said.

Harvesting the resource of urine — which is, after all, full of the same nutrients as chemical fertilizer — will fix two problems at once: eliminate waste and create a natural fertilizer.

The Rich Earth Institute has been using urine as fertilizer since 2012. Kim Nace says they collect about 26,000 liters a year, thanks to a loyal group of dedicated donors.

“We now have people who have some source-separating toilets in their homes. We also have people who have 55 gallon (200-liter) barrels where they collect and then we transport to our farms, and we’ve also got a large urine depot,” Nace said.

They pasteurize the urine to kill any microbes, and then it is applied directly onto hay fields like Hamilton’s.

Next level of project

Now that they’ve partnered with the University of Michigan, Love says they’re looking to take their project to the next level.

“There are three things we really are trying to do with the urine in this kind of next phase. We’re trying to concentrate it. We’re trying to apply technologies to reduce odor, and we’re trying to deal with trace contaminants like the pharmaceuticals,” she said.

Dealing with pharmaceuticals is an important issue. Heat urine kills germs but has no effect on chemicals like drugs that pass through our bodies.

“We know pharmaceuticals are a problem for aquatic organisms and water systems,” Love said. “It’s debatable about the impact on human health at very, very low levels. Independent of that, I think most people would prefer that they not be in their food.”

21st century infrastructure

For Love, this is all about redesigning our wastewater infrastructure for the 21st century. Too many nutrients in the water leads to poor water quality by causing hazardous algal blooms.

“Our water emissions are going into very sensitive water bodies that are vulnerable to these nutrient loads,” she said. “We need to change that dynamic. And if we can capture them and put them to a beneficial use, that’s what we’re trying to do.”

Their efforts could make agriculture greener and our waterways cleaner.

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Main functions of plant nutrients

Nutrient

Functions

Nitrogen (N)

Synthesis of proteins (growth and yield).

Phosphorus (P)

Cellular division and formation of energetic structures.

Potassium (K)

Transport of sugars, stomata control, cofactor of many enzymes, reduces susceptibility to plant diseases.

Calcium (Ca)

A major building block in cell walls, and reduces susceptibility to diseases.

Sulphur (S)

Synthesis of essential amino acids cystin and methionine.

Magnesium (Mg)

Central part of chlorophyll molecule.

Iron (Fe)

Chlorophyll synthesis.

Manganese (Mn)

Necessary in the photosynthesis process.

Boron (B)

Formation of cell wall. Germination and elongation of pollen tube.
Participates in the metabolism and transport of sugars.

Zinc (Zn)

Auxins synthesis.

Copper (Cu)

Influences in the metabolism of nitrogen and carbohydrates.

Molybdenum (Mo)

Component of nitrate-reductase and nitrogenase enzymes.

Nutrient Management for Sunflower Production

Fertilizer management is an important part for sunflower production and one must know how input affects the crop and soil traits. Determination of optimum fertilizer rates is important because of increasing economic and environmental concerns. This study was therefore conducted to determine optimum fertilizer and manure requirement for sunflower production. In this regard, three field experiments were conducted at Students Farm, Sindh Agriculture University, Tandojam, Pakistan, located at 25o25’60’N 68o31’ 60E, altitude 19.5 m asl. In all the experiments sunflower variety HO-1 was sown in rows (75 cm spacing). The experiment-1, was meant to evaluate NPK, Zn and B requirements for sunflower production. The treatments consisted: Factor-A=Seasons (Spring and Autumn), Factor-B NPK Levels (0-0-0 NPK kg ha-1, 60-30-30 NPK kg ha-1 (N as broadcast), 90-45-45 NPK kg ha-1 (N as broadcast), 120-60-60 NPK kg ha-1 kg ha-1 (N as broadcast), 60-30-30 NPK kg ha-1 (N as fertigation), 90-45-45 NPK kg ha-1 (N as fertigation) and 120-60-60 NPK kg ha-1 (N as fertigation) and Factor-C (zinc and boron levels (0-0, 10.0-1.5, 10.0-2.0, 15.0-1.5, 15.0.2.0, 20.0-1.5 and 20.0-2.0 Zn+B kg ha-1). The results recorded taller plants (207.2 cm), maximum stem girth (12.2 cm), better head diameter (23.0 cm), more seeds head-1 (696.4), heavier seeds weight head-1 (49.0 g), bolder seed index (71.2 g), maximum seed yield (2743.0 kg ha-1) and higher dry matter (11666.7 kg ha-1), higher N-uptake (70.2 kg ha-1), P-uptake (19.1 kg ha-1), K-uptake (93.9 kg ha-1), Zn-uptake (335.8 g ha-1) and B-uptake (199.2 g ha-1) under application of 90-45- 45 NPK x 15-1.5 Zn-B kg ha-1 (N applied as fertigation). Similarly, higher values of physiological traits at flowering phase i.e dry matter (1353.0 g m-2), leaf area index (5.7), leaf area duration (55.6 days), crop growth rate (8.7 g m-2 day-1) and net assimilation rate (24.3 g m-2 day-1) were also noted for the same treatement.

sunflower1However, oil content in this Interactive effect showed non-significant differences. The regression coefficient (b) revealed that a unit increase in various traits resulted in corresponding increase of sunflower seed yield by head diameter (101.2 kg ha-1) seeds head-1 (6.2 kg ha-1), seed weight head-1 (55.2 kg ha-1), seed index (58.2 kg ha-1), dry matter (0.3 kg ha-1), leaf area index (1108.3 kg ha-1), leaf area duration (113.4 kg ha-1), crop growth rate (378.4 kg ha-1), net assimilation rate (213.7 kg ha-1), nitrogen uptake (27.4 kg ha-1), phosphorus uptake (131.8 kg ha-1), potassium uptake (32.4 kg ha-1), zinc uptake (6.5 kg ha-1) and boron uptake (10.9 kg ha-1). However, a unit increase in seed oil content resulted corresponding decrease in seed yield by 1339.2 kg ha-1. The experiment-2, involved “Integrated use of organic manures and inorganic fertilizers nutrients for sunflower production” The treatments consisted: no manure, cattle manure (5, 10 and 15 tons ha-1) and poultry manure (5, 10 and 15 tons ha-1) with 90-45- 45 NPK + 15 Zn + 1.5 B (kg ha-1). The results of the study showed that the incorporation of fertilizers and manures significantly enhanced all the crop parameters. The taller plants (232.3, 231.2 cm), more stem girth (13.9, 13.9 cm), maximum head diameter (27.1 and 26.5 cm), higher number of seeds head-1 (801.9 and 797.9), heavier seed weight head-1 (66.6 and 65.9 g) bolder seed index (83.2 and 83.0), superior seed yield (3681.8 and 3643.2 kg ha-1) and higher dry matter at harvest (12859.3 and 12845.0 kg ha-1), higher Nuptake (80.7 and 82.2 kg ha-1), P-uptake (24.2 and 24.5 kg ha-1), K-uptake (114.2 and 114.0 kg ha-1), Zn-uptake (531.9 and 530.4 g ha-1) and B-uptake (320.4 and 314.9 g ha-1), higher dry matter (2075.0 and 2066.7 g m-2), maximum leaf area index (7.2 and 7.2), greater leaf area duration (67.4 and 67.3 days), more crop growth rate (10.3 and 10.2 g m- 2 day-1) and superior net assimilation rate (30.7 and 30.7 g m-2day-1) were recorded under cattle manure 10 t ha-1 + 90-45-45 NPK + 15-1.5 Zn-B kg ha-1 and poultry manure 5 t ha-1 + 90-45-45 NPK + 15-1.5 Zn-B kg ha-1, respectively, where N was applied as fertigation. Whereas, seed oil content showed inverse relationship under higher applications of inorganic fertilizers and manures. It was observed that application of poultry manure at 5 tha-1 or cattle manure at 10 t ha-1 with 90-45-45 NPK + 15-1.5 Zn-B kg ha-1 significantly enhanced all these traits and beyond these treatments no significant differences were exhibited even at higher levels of manures and were economically optimum levels for achieving satisfactory crop parameters. The regression coefficient indicates that a unit increase in various traits resulted in corresponding increase of sunflower seed yield by head diameter (150.0 kg ha-1) seeds head-1 (6.5 kg ha-1), seed weight head-1 (53.1 kg ha-1), seed index (62.8 kg ha-1), dry matter (0.4 kg ha-1), leaf area index (1027.5 kg ha-1), leaf area duration (116.0 kg ha-1), crop growth rate (469.9 kg ha-1), net assimilation rate (218.3 kg ha-1), nitrogen uptake (36.1 kg ha-1), phosphorus uptake (172.1 kg ha-1), potassium uptake (40.4 kg ha-1), zinc uptake (5.9 kg ha-1) and boron (9.5 kg ha-1). However, a unit increase in oil content resulted corresponding decrease in seed yield by (1546.3 kg ha-1). The experiment-3 entitled “residual effect of organic manures and supplemental inorganic fertilizers on sunflower production” revealed prolonged maturity (99.3 and 99.33 days), taller plants (258.1 and 256.9 cm), more stem girth (16.2 and 16.2 cm), maximum head diameter (31.1 and 31.0 cm), higher number of seeds head-1 (888.1 and 884.2), heavier seed weight head-1 (80.1 and 79.7 g) bolder seed index (90.9 and 92.0 g), superior seed yield (4420.2 and 4450.4 kg ha-1) and higher dry matter (14395.9 and 14381.2 kg ha-1), higher N-uptake (100.9 and 100.3 kg ha-1), P-uptake (33.9 and 33.7 kg ha-1), K-uptake (159.1 and 158.8, kg ha-1), Zn-uptake (603.0 and 605.1g ha-1), B-uptake (361.0 and 364.7 g ha-1), maximum leaf area index (7.9 and 7.9), greater leaf area duration (76.0 and 75.8, days), higher dry matter (2808.7 and 2740.4 g m-2), more crop growth rate (12.1 and 12.0 g m-2 day-1) and superior net assimilation rate (36.9 and 36.0 g m-2day-1) were recorded under residual cattle manure 10 t ha-1 + 90-45-45 NPK + 15-1.5 Zn-B kg ha-1 and residual poultry manure 5 t ha-1 + 90-45-45 NPK + 15-1.5 Zn-B kg ha-1 respectively where N applied as fertigation and beyond these treatments no significant increase in all the crop traits was noted. The regression coefficients indicate a unit increase in various traits resulted in corresponding increase of sunflower seed yield by head diameter (157.2 kg ha-1) seeds head-1 (7.3 kg ha-1), seed weight head-1 (53.7 kg ha-1), seed index (67.9 kg ha-1), dry matter (0.4 kg ha-1), leaf area index (1064.0 kg ha-1), leaf area duration (111.2 kg ha-1), crop growth rate (456.8 kg ha-1), net assimilation rate (195.3 kg ha-1), nitrogen uptake (36.0 kg ha-1), phosphorus uptake (143.0 kg ha-1), potassium uptake (33.3 kg ha-1), zinc uptake (6.5 kg ha-1) and boron (10.3 kg ha-1), however, a unit increase in oil content resulted in corresponding decrease in seed yield by 2037.6 kg ha-1. It is concluded that the fertilizers and manures enhanced all the crop traits, nutrient uptake and improved soil fertility. The application of NPK (90-45-45 kg ha-1, N applied as fertigation) + Zn+B (15+1.5 kg ha-1) with 10 t ha-1 of cattle or 5 t ha-1 poultry manure for their residual effect in the subsequent crop were superior and optimum fertilizer and manure doses for sunflower production without degrading fertility of soil. It is suggested that any source of well decomposed organic manures could be incorporated in the field to enrich the soil fertility on long term basis and higher sunflower production. Thus, it is recommended that sunflower crop should be fertilized with incorporation of NPK (90-45-45 kg ha-1, N as fertigation) + Zn+B (15+1.5 kg ha-1) with 10 t ha-1 cattle or 5 t ha-1 poultry manures for satisfactory yield and maintenance of soil fertility.

Source: SIDDIQUI, MUZZAMMIL HUSSAIN (2010) Nutrient Management for Sunflower Production. PhD thesis, Sindh Agriculture University, Tando Jam