Rice farmers advised to adopt SRI tech for higher yield

Noticing the falling yield of rice in Pakistan the United Nations Global Compact (UNGC) representative has urged the Pakistani rice farmers to adopt the System of Rice Intensification (SRI) prepared by the World Bank Institute (WBI) and widely practiced in several rice growing countries successfully for achieving higher productivity and water savings.Rice farmers advised to adopt SRI tech for higher yield-Agriculture Information Bank(agrinfobank.com)
In a statement Zulfikar Thaver member UNGC lauded the efforts of the WBI for preparing and promoting the SRI and said that the SRI is a guide for rice farmers and teaches them rice planting and water management for increase in yield and income. It is based on six key elements and educates the rice farmers in land preparation, seedlings preparation, innovative transplanting, intermittent irrigation, rotary weeding and organic fertilisation.
He said it is a marvelous system which can give remarkable improvement in yield per acre and lowers cost of production scientifically.
After studying the SRI one realises the need to adopt the system without loss of time. It is pertinent to note that no heavy farm machinery is required as it is very simple and its application is based on methods and techniques and simple devices are used in plantation after land preparation and intermittent irrigation under single plantation techniques.
He urged the ministry of agriculture to immediately contact the WBI and plan to introduce the SRI for the next cultivation for all varieties of rice in all the provinces for best results.
 

News Source                            News Collated by agrinfobank.com Team

Courtesy The Nation

Irrigation: Physical importance

Irrigation is the artificial supply of water to the plant/crops, according to the free dictionary(http://www.thefreedictionary.com/) irrigation is define as To supply (dry land) with water by means of ditches, pipes, or streams; water artificially. Following are the some important function or role of irrigation in plant physical and physiological process;Irrigation: agrinfobank.com

• The plant system itself contains about 90% of water.
• Amount of water varies in different parts of plant as follows.
* Apical portion of root and shoot > 90%.
* Stem, leaves and fruits 70–90%
* Woods 50–60%
* Matured parts 15–20%
* Freshly harvested grains 15–20%
• It acts as base material for all metabolic activities. All metabolic or biochemical reactions in plant system need water.
• It plays an important role in respiration and transpiration.
• It plays an important role in photosynthesis.
• It activates germination and plays an important role in plant metabolism for vegetative and reproductive growth.
• It serves as a solvent in soil for plant nutrients.
• It also acts as a carrier of plant nutrients from soil to plant system.
• It maintains plants temperature through transpiration.
• It helps to keep the plant erect by maintaining plant’s turgidity.
• It helps to transport metabolites from source to sink.

U-Bar Dig

1. After harvest, if necessary, weed the entire slightly raised bed.
2. When the soil is lightly moist, begin U-barring the soil along the length of the bed. No digging board is used. The soil will be loosened 3⁄4 as deep as in the double-dig.
3. Continue U-barring until the bed is done. Two or three U-bar passes along the length of the bed may be necessary epending on the bed’s width. The U-bar is about 2 feet wide and loosens the soil 2 to 2 1⁄2 feet wide. U-Bar Dig: agrinfobank.com
4. Break up any remaining large clumps with a spading fork. Shape the bed by raking it. Then evenly spread compost and any needed fertilizers over the entire area, and sift them in 2 to 4 inches deep with a spading fork.

Engro Foods enters fresh dairy segment

Engro Foods Limited, the fastest growing Pakistani multinational company entered the fresh dairy industry of Pakistan with their new brand “Mabrook”. The company’s objective is to tap into the dominant Fresh Loose Milk segment using the pasteurisation process.
‘Mabrook’ offers all the benefits of Fresh Milk, ie consistent cream (balai) yield, value in usage (yogurt, butter, ghee, direct consumption, etc) and daily fresh supply of milk at Mabrook shops. Keeping the Loose milk consumer insights into view, the milk is sold through milk outlets and is dispensed hygienically to ensure that the best possible quality product reaches the consumer. Engro Foods enters fresh dairy segment: agrinfobank.comSpeaking at the occasion, Sarfaraz A Rehman, CEO, Engro Foods said: “Out of 20 billion liters of tradable milk in Pakistan, the unbranded fresh dairy holds almost 74 percent for the share in the industry. We wanted to tap into that category and offer a value-added product to this key segment of the Pakistani market–living our purpose of elevating consumer delight for a wide section of the society.
Although we are selling our product through milk outlets, the product is backed by our commitment to quality excellence–a fact visible through our local and international certifications. We are hopeful that Mabrook with its unique proposition and better quality will offer a more economic and healthy choice to our consumers.” Mabrook is Engro’s response to the loose milk consumers’ need for fresh, clean and unadulterated milk; bringing a product that is affordable while delivering quality and staying true to its offering
.

Courtesy Business Recorder  I News Collated by agrinfobank.com

Rabbit Farming

Meat rabbit farming is one of the fastest growing new industries. While its long term size will never rival that of our traditional meat industries, it is providing a useful source of  income diversification for a number of people in regional and rural areas where farm incomes  have plummeted in recent years.

Rabbit farming have following benefits;

  1. With available small investment and in a small place rabbit farming gives  more income
  2. Rabbits eat ordinary feed and convert them into a protein rich high quality meat
  3. Apart from meat production they can also be reared for hide and fur
  4. By rabbit rearing one can produce a quality protein rich meat for his own family
  5. Litter size (Number of young ones born/ kindling)  in rabbits is high (around 8-12)
  6. Growth  rate  in  broiler  rabbits  is  very  high.  They  attain  2  kgs  at  the  age  of  three months

A successful rabbit farming required proper knowledge about rabbits and adopt best management practices, housing is very important in rabbit farming. In general, the type of housing is dependent upon the climate, location and size of the rabbitry. The optimum temperature in a rabbit shed is around 10 – 25 0C (SCARM 1998). Effective ventilation is required to control extremes of temperature and also to remove ammonia. Housing is a critical issue for rabbit health. Poor ventilation will result in irritationto the respiratory tract and susceptibility to infection from bacteria. Heat stress will cause major rabbit mortalities and reproductive failure. Rabbit Farming I agrinfobank.com

1..   Ventilation
A discussion of different ventilation systems can be found in McNitt et al. 1996. The following summary covers the main points. Natural ventilation systems can use wind and animal heat to move air. Natural ventilation is low cost, the disadvantages being lack of control over air movement, inability to lower the inside temperature of the rabbitry below that outside, and over-ventilation. Natural ventilation can be provided with a high gable roof, a ridge vent, and open sides with flaps that can be opened or closed depending on the  atmospheric requirements. In high wind areas,a stub wall or wind baffle outside the open  sided sheds is needed to reduce wind velocity. Mechanical ventilation systems are used in  environmentally controlled buildings, using fans to provide required airflow. The advantage  of this system is the ability to control rate of airflow for effective removal of moisture, heat and ammonia; disadvantages being the high initial and operating cost and the need for back up  systems in case of power failure.Evaporative cooling systems may be used in a hot, dry climate. A water sprinkling system on the roof of the rabbit shed will help to reduce high temperatures.

2..   Space requirements
The following information is drawn from the code of practice published for intensive husbandry of rabbits in Australia (SCARM 1998). Sufficient room is required for caged  rabbits to move around, to feed and drink without difficulty. The minimum legal standards for different classes of rabbits are given below:

Doe and litter (5 weeks) 0.56 sq.m(total area)
Doe and litter (8 weeks) 0.74 sq.m(total area)
Rabbits (5-12 weeks) 0.07 sq.m(per rabbit)
Rabbits (12 weeks or more) 0.18 sq.m(per rabbit)
Adult does and bucks for breeding 0.56 sq.m
Cage height (>12 weeks) 45 cm

If the floor of the cage is of wire mesh material it should be of woven or flat construction. The square mesh of the floor should not exceed 19 x 19mmfor adults and 13 x 13 mm for kittens. The optimum for rectangular mesh is 50 x 13 mm. The thickness of the wire mesh should not  be less than 2.5 mm diameter (12 gauge). Cage arrangement can vary depending on the size of  the enterprise. Multiple deck configurations require a faeces diverter or multi deck conveyor belt.

3.  Feeders and watering equipment
Good feeding and watering equipment will supply feed and water in hygienic condition and will avoid causing discomfort or stress to the rabbits. “J” type feeders are most widely used. A  feed hopper in a cage should have a sufficiently big opening and should be large enough to  feed all the rabbits in the cage at the same time. An automatic watering system can be  installed. The drinking nipples of the watering system should be at optimum height from the floor of the cage, around 10 cm from the floor of the cage and they should not project more than 2.5 cm into the cage (SCARM 1998). It is always advisable to have a backup system to  ensure that rabbits have access to water in case of a failure of an automated system.

FEEDING
There are some detailed publications on rabbit feeding such as the book by Cheeke (1987). The following information has been reproduced from the Thumper Newsletter. The average daily requirement of pelleted feed for rabbits of different ages is given below:
Does 100g
Pregnant does 160g
Lactating does 350g
Oaten chaff can be fed at the rate of 20 g per day per adult rabbit.  Pellets should be formulated to give basic nutrient requirements for rabbits. This information is available in Cheeke (1987).

Vegetables, fruits: supply system made further effective: minister

Punjab Food Minister and Chairman Price Control Committee Bilal Yaseen said supply system of vegetables and fruits have been made further effective in all markets of districts across Punjab. He said, as a result of government steps, prices of everyday items have been reduced, due to which edible items have now become accessible to the common man. Vegetables, fruits: supply system made further effective: ministerThe Provincial Food Minister expressed these views while monitoring auction of vegetables and fruits at Badami Bagh Market early morning. He said Punjab government has made foolproof planning to provide relief to the common man, due to which price hike has been controlled to a great extent. He said profiteers and illegal overcharging elements have now been brought under the grip of strict law, due to which citizens have been made available vegetables, fruits and everyday items at affordable rates. Food Minister directed staff deputed at Badami Bagh Fruit Market to ensure their presence at the hour of auctioneering at the market, along with prominently displaying rate list of vegetables and fruits.

Courtesy Business Recorder  I News Collated by agrinfobank.com

Gas provision to fertilizer plants to help save foreign exchange: FMPAC

Fertilizer Manufacturers Pakistan Advisory Council (FMPAC) said government can save precious foreign exchange on account of urea import if it provides gas to local fertilizer manufacturer plants. Urea import is no permanent solution of rising urea demand by local fertilizer sector and best way to ensure less expensive and timely availability of urea to farmers is to produce it locally. Gas provision to fertilizer plants to help save foreign exchange: FMPAC: agrinfobank.com
FMPAC spokesman said here on Thursday that few fertilizer plants were completely shutdown due to closure of gas as part of winter gas load management plan by the government but there was no shortage of urea in the market. Spokesman demanded if any vested interest was found involved in hoarding, government should take stern action against them to ensure timely availability of urea to farmers at the prescribed rates.
He said local fertilizer plants had been trying to persuade the government to maximise the local urea production to avoid spending hundreds of millions of dollars each year on urea import and if government decided not to import urea, “we have ample capacity not only to meet the domestic urea requirements but also to export it.”
FMPAC sources said “our economy is not in a position to drain precious foreign exchange on unnecessary urea import while we can produce it locally at relatively cheaper cost. The devaluation in rupee’s value and appreciation in dollar’s value has already made it an expensive affair.” Country faced massive loss in urea production due to excessive gas curtailment in the past three years that has cost significantly to the country as GoP had to spend foreign exchange of US $1.5 billion and subsidy of around Rs 80 billion on the imports of 3.4 million tons during 2010-12.
Pakistan is self-sufficient in urea production and with consistent gas supply to these plants, government can ensure timely availability of this key farm input to farmers at the cost-effective rates and would also help GoP to reduce its fiscal deficit as well as subsidy spend.

Courtesy Business Recorder I  News Collated by agrinfobank.com.pk

Hydroponics – a quick overview

Truly a wonder of modern science – hydroponic gardens produce bountiful harvests of fruit, vegetables, grains, herbs and flowers in places never before able to sustain growth. Hydroponic gardens produce the healthiest crops with the highest yields and vitamin content thanks to their perfectly balanced nutrient solutions. Modern hydroponic methods provide food for millions of people worldwide and supply you, me and the food service industry with superior produce. In fact, hydroponic cultivation is so effective, NASA has devised an advanced method of hydroponics for use in outer space. The science of hydroponics began with experimentation into deter-mining the elementary composition of plants. These experiments have been dated as early as 1600 A.D., however, records show that plants have been cultivated in soil free mixtures of sand and gravel even earlier. The hanging gardens of Babylon and the floating gardens of the Mexican Aztecs are perfect examples of early hydroponic gardening. Egyptian hieroglyphics have even been found depicting the cultivation of plants in water as far back as several hundred years BC.

The word “Hydroponics” was coined by Dr. W.F. Gerick in 1936 to describe the cultivation of both edible and ornamental plants in a solution of water and dissolved nutrients. The simple meaning is derived from the Greek “Hydro“- meaning water, and “Pones“- meaning labor. In this method of cultivation, plants are provided with the nutrients required for growth by a “nutrient” solution which is basically nutrient enriched mineral water. This nutrient solution can be circulated around the roots by  either the passive force of gravity or the active force of an electromechanical pump. Some systems simply bath the roots in nutrient solution and use an air pump to oxygenate the solution from below to prevent stagnation and provide the roots with important oxygen.

Hydroponics an overviewPlants grown hydroponically are healthier than their soil grown counterparts since they receive a perfectly balanced diet and do not come in contact with soilborne pests and diseases. Super efficient hydroponic systems like the ones we show you how to build conserve water and nutrients by preventing evaporation and runoff. Arid regions where water is scarce can now grow crops with hydroponics. Since hydroponic systems deliver water and nutrients directly to the plant, crops can be grown closer together without starving each other and healthier plants add to a higher yield. By growing crops in a sterile environment, under ideal conditions, hydroponics saves the costs of soil preparation, insecticides, fungicides and losses due to drought and ground flooding.

In soil, plants waste a tremendous amount of energy developing a large root system to search for moisture and nutrients. When grown hydroponically, the roots are bathed or sprayed with nutrients dissolved in water. This way their energy can be redirected into the production of more foliage, flowers, fruits and vegetables.
Plants grown hydroponically are healthier because they receive a well balanced ‘diet’. They are more vigorous because little energy is wasted searching for water and nutrients. As a result, hydroponically grown produce is generally larger, tastier, and more nutritious than the same produce grown in soil. In order to give the physical support soil would normally provide, a sterile medium such as sand, gravel, rocks, cocofiber or rockwool (or combination of each) may be used. In the case of aeroponics, no medium is used and the plants receive physical support from baskets and in this case, wires suspended from the roof. These plants are rotated through a chamber that supplies their roots with a fine spray of water and hydroponic nutrients.Advertisement3

Oxygen to the roots increases a plant’s metabolism substantially. Some advantages of replacing soil with a sterile medium are:
1. Elimination of soil borne pests, funguses and diseases.
2. Elimination of troublesome weeds and stray seedlings.
3. Reduction of health risks and labor costs associated with pest management and soil care. 
At the Environmental Research Laboratory (ERL) at the University of Arizona in Tucson, Dr. Carl Hodges and Dr. Merle Jensen in conjunction with Walt Disney Productions, have developed new concepts for presenting hydroponic technologies to the public in an entertaining way. The ERL helped create two attractions called “Listen to The Land” and “Tomorrow’s Harvest” – both major facilities at Epcot Center near Orlando, Florida. Hydroponics is NASA’s solution to provide a self sufficient food source for future space stations and proposed visitors to mars. The administration has sponsored a research program titled Controlled Ecological Life Support System (CELSS) in order to further develop the technology and carry it into the future. The picture below is of Epcot/ NASA’s Space Agriculture expo as seen from a tour of the Epcot Center attraction. The lighting used in these examples is high pressure sodium or HPS, which delivers an excellent spectrum of color and output in lumens. High Intensity Discharge (H.I.D.) lighting, which includes the HPS and metal halide type lamps, is the best lighting to use when gardening indoors or supplementing natural lighting outdoors due to its efficiency and close representation of the sun’s natural light color and intensity.

Source: Oasis Agro Industries Pakistan

Modern agriculture-how to proceed

Ali Ahsan Bajwa, Dr. Muhammad Farooq, Usman Zulfiqar

Department of Agronomy, University of Agriculture, Faisalabad, 38040.Pakistan

I guess change is the only constant in world. Everything has to change with time sooner or later. Agriculture is one of the most important and old occupations. People used to grow crops and rear animals to meet their food and accommodation requirements since ancient times. These requirements have climbed enormously with the passage of time. Agriculture has changed and is still changing with modern trends of time. Modern agriculture is quite different from conventional one. Previously lands were disturbed with bullocks and seeds were dispersed by hands. A person used to grow grains and grasses on small piece of land by adding dunghill of his domestic animals to feed his family and the same animals. Milk, meat and eggs were available at the cost on-farm produced grains and forage. Groundwater was sweet enough to drink, to bath and to grow crops and vegetables. Yields far below than present levels, were sufficient to feed farming community and to earn necessary money through give and take trading system. Lands were blackish with maximum organic matter and crop produce was pure and healthy. Incidence of diseases in plants and animals were not as much frequent and severe as now. Meanwhile, people were contended with lesser income and profits. Environment was safe due to the absence of agro-chemicals, synthetic fertilizers, growth regulators, heavy machinery, industry and luxury. This was the story of old agriculture which is not prevalent anymore because of elevated levels of population, increased urbanization, industrialization, commercialization, rising desire for money and eagerness for so-called “modernization”. wheat

Threats:

Modern agriculture in my opinion is a broad spectrum term covering all the advances being used in agriculture to enhance per unit production and per capita availability of food. It relates to the production process and marketing regimes. Modern agriculture requires heavy inputs along with mechanization to ensure maximum production. The process of crop production begins from sowing. The manipulation of soil for the provision of good environment to plants is necessary. This process of soil tillage and its intensity in modern agriculture is of key importance. It has been common practice to cultivate, shuffle and level the soil intensively at frequent basis. It is inevitable as people are trying to get more crops per year and then more production of each crop. Keeping in mind the fact that all the nutrients required to crop has to be taken up from soil, disturbance of soil becomes first priority. The same soil which was strong enough to provide essential elements to plants previously has become deficient of all. It is because of increased intensity of crops. Cropping intensity of Pakistan has increased from 25% to 150%. This much exploitation of soil has made it less fertile and less productive. People are trying to explore maximum potential and maximum crops from a unit area. Most of the time crops cultivated are exhaustive in nature. It means modern agriculture has also deviated from basic principles like planned crop rotations. There is no such involvement of restorative crops indeed. http://www.agrinfobank.com

MODERN AGRICULTURE-HOW TO PROCEEDTrend of monocropping has introduced the problems of specific weed flora development, insect-pests attacks, diseases incidence, weeds herbicide resistance, micronutrients deficiency and reduction in yield. Salient feature of modern agriculture is the maximum use of synthetic chemical fertilizers, growth regulators, soil conditioners, herbicides, pesticides, fungicides, insecticides, nematocides and wormicides. I refer “homicidal” as single but comprehensive word for all these. These are being added to the environment without any check just to have a quick control of problematic agents in crops. The farmer who was once reluctant to adopt these “poisons” has embraced the luxury and is blindly using all these. We are ridiculously feeding the earth with poisons to get blessings in the form of food grains, fruits and vegetables. Perhaps modern age has scratched the saying “as you sow, so shall you reap” from our greedy brains. Same dismal picture is for all natural sources like water, air, light, forests, deserts, mountains, flora, fauna and biodiversity. Modern man with its modern agriculture is playing havoc with all these beauties. Land is being degraded through accelerated erosion, salinity, waterlogging fertility loss. Ground water is no fit for irrigation because of more soluble salts and heavy metals in it. Rivers, lakes and oceans are being awarded with industrial effluents, agro-chemicals, municipal wastes and bio-excreta. Non-judicious use of farm machinery has increased fuel consumption, green house gases (GHGs) emission and soil degradation simultaneously. Oxides of N, O2, C and S are being released through agro-ecosystem in biggest proportion which cause the haunting catastrophe of modern age, global warming. This mechano-chemical setup has induced drastic changes around the globe. Ali Ahsan's profile photo

Global temperature is rising furiously, glaciers are melting and floods are coming. Rainfall patterns are changing that cause alternate flooding and drought onsets. Heat, cold, drought and submergence stresses are affecting the very same crop production due to which they prevails. Our needs have compelled us to apply the same irrational formula of production on livestock, poultry and fishery sectors. Factory-farming of meat and milk animals is also the “blessing” of modern agriculture. It is again due to increased food requirements. Animals are reared at sub-standard health conditions at commercial basis. High use of synthetic feed and regulators irrespective the animal health and requirement is done. It is an immoral way to fulfill food requirements by human-beings. Utilization of such chemicals offer sub-optimal conditions for animals and influence their health severely.

No doubt, science has gifted us modern technologies. These facilitate and provide ease, efficiency and perfection in agricultural processes. But the intensity, timing and frequency of their use make them blessing or calamity. In modern day agriculture focus is on resource exploitation, energy exploration, production enhancement and profit maximization. Food quality management, environmental protection, economic stability, moral obligations, natural resource conservation and system sustainability has been given secondary importance. This is injustice with us, coming generations and nature.

Suggested solutions:

My knowledge is poor, my abilities are fragile, my intellect is faint and my experience is small but my sense of realization of this matter is bigger than me. That realization is key for thinking about solution. Being an agrarian I have some simple but pragmatic points that can help in this regard:

  • Immediate adoption of resource conservation technologies

  • Start moving towards conservation agriculture slowly but surely

  • Adopt sustainable measures in farming

  • Proper but minimum use of agro-chemicals along with mechanical, manual and cultural approaches to control agricultural pests may help a lot

  • Ecological options like cover crops, intercropping and true crop rotations must be considered

  • Agricultural lands should not be devoted for industry or urban settlements

  • Water bodies must be protected and addition of drain’s water, industrial effluents and municipal wastes should be strictly banned

  • Agro-forestry should be promoted to enhance sustainability and biodiversity

  • Use of natural products, manures and amendments should be encouraged

  • Integrated approaches must be adopted. As we can neither reduce our population nor leave modern agriculture but decrease in use of harmful technologies and increase in use of natural options is possible. So, integrated weed management (IWM), integrated pest management (IPM), integrated disease management (IDM) and integrated nutrient management (INM) can make modern agriculture safe and suitable.

  • Proper policy making and then fair implementation is very much necessary

  • Action plans should be developed by research organizations, extension wing and educational institutes to discourage harmful practices of modern agriculture

  • Awareness must be provoked in farming communities in this regard

  • Influence of low standard pesticide companies in rural areas must be restricted

  • Focused and comprehensive research is much needed to develop resource efficient techniques, to frame sustainable practices, to modify cropping schemes and cropping rotations, to improve farming systems and to reinforce natural phenomena

  • Improved cultural practices (ICPs), recommended crop husbandry practices (RCHCs), on-farm management practices (OMPs) and good agricultural practices (GAPs) are collectively key to success and must be adopted

  • Consistent efforts with logical modifications are pre-requisite for a better production system http://www.agrinfobank.com

Modern agriculture is not a bad thing at all and we cannot shift towards the agriculture of our fathers. But some poor management is governing us to the destruction which we can stop easily by adopting above mentioned rules. It could be a safe agriculture within the same resources, conditions and requirement just through better management. It is need of the hour to regulate our farming practices once again for secure future of us and our coming generations. I believe it’s the time to take these issues seriously and to make our mind for certain changes. A crucial initiative in this regard is required somewhere from government, research organizations or farming community. Someone has to break the ice and to embark upon the expedition of reform. Changing political and organizational setups will not help unless or until we decide to move with this enlightened vision.

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Anatomical Differences Between Crop and Weed

The amount of spray retention by foliage after postemergence applications can affect selectivity. This selectivity is usually due to the crop plant’s having a waxy cuticle that repels the spray solution.Examples include onions, peas, cereal grains, Brassica vegetable crops, and conifers. Medium to high spray volumes usually provide better selectivity, and adding an adjuvant can decrease selectivity as a result of enhanced adhesion of the spray droplets. Anatomical Differences Between Crop and WeedDifferences in leaf shape, size, and orientation between weed and crop can provide some selectivity differences. This is most common for controlling dicot weeds in small grain crops (the grain leaves retain less herbicide because of shape, orientation, size, and granular epicuticular wax). Postemergence selectivity can be due to the growing point of the crop being protected from direct contact by the herbicide while the growing point of the weed is exposed. The best example is dicot weed control (growing point not well protected by emerging leaves) in small grains (growing point well protected by the whorls of emerging leaves). The herbicide must not have a high degree of phloem mobility for this selectivitymechanism to work. For more detail regarding the influence of plant morphology on herbicide absorption, see the review by Hess (1987).

Preemergence selectivity can be due to a difference in root morphology between the weed and the crop. Grass weeds usually have a fibrous root system, whereas dicot crops usually have a taproot system. Thus,growth inhibitor herbicides, such as trifluralin, applied to the soil come directly in contact with the growing root tips in grass weeds, but not with those of the deeper-rooted dicot crops. For this selectivity mechanism to be useful, the water solubility and soil binding characteristics of the herbicide must be such that movement isrestricted to the upper soil profile.
Morphology differences within stem tissue of grass plants can provide differences in selectivity. The growing point of many grass weeds (crabgrass and wild oat) are more exposed to herbicide-treated soil than wheat and barley where the growing point is protected inside the coleoptile.