Moisture stress management in Horticulture crops
The topic provides information about general recommendations for rain deficit moisture stress management in Horticulture crops.
- Selection of suitable crops and varieties
- Improved method of seedling production
- Adoption of soil and moisture conservation techniques
- Enhancing soil organic matter content
- Application of foliar nutrition:
- Use of drip irrigation
- Use of micro sprinkler irrigation
Depending upon situation and availability of water, this technology can be used for fruits and vegetable crops. The cost of initial establishment is lower compared to drip system. Further in summer the sprinkling of water helps in reducing the microclimate temperature and increasing the humidity, thereby improving the growth and yield of the crop. The water saved is to the tune of 20 to 30 per cent.
- Moisture saving methods under limited water resource conditions:
In vegetable crops like dolichos bean, cowpea, cluster bean, lima bean, chilli, drumstick, brinjal, okra are suitable for rain-fed cultivation. Among these, legume vegetables can be recommended for contingency crop-planning in an eventuality of late monsoon rains. Varieties having good root system and capacity to recoup after the alleviation of stress need to be selected. Depending upon situation, it is recommended to use short duration varieties.
Improved method of seedling production such as Protray grown seedling using coco peat, nylon net protection and bio-fertilizers/bio-pesticide inoculation at nursery stage has good potential for obtaining sturdy, uniform and healthy seedlings. These seedlings when transplanted in the main-field will establish better with less root damage and fare better in overcoming biotic and abiotic stresses particularly during water stress conditions.
Contour cultivation, contour trip cropping, mixed Cropping, tillage, mulching, zero tillage, are some of the agronomical measures for the in-situ soil moisture conservation. Mechanical measures like contour bunding, graded bunding, bench terracing, vertical mulching etc. also need to be followed for effective soil and moisture conservation in dry lands. Another technology for efficient utilization of runoff is water harvesting recycling. Rainwater harvesting includes collecting runoff water into dug out ponds or tanks in small depressions, gullies and into storage dams of earth or masonry structures. Rain water harvesting is possible in areas having rainfall as little as 500 to 800 mm. Depending on the rainfall and soil characteristics, 10-50 % of the runoff can be collected in farm pond. Surface run off thus collected in a farm pond can be used to provide protective irrigation in the period of prolonged dry spell or through microirrigation techniques.
Constant efforts must be made to improve the soil organic carbon. Incorporation of crop residues and farm yard manure to soil improves the organic matter status, improves soil structure and soil moisture storage capacity. Organic matter content of the soil can also be improved by fallowing alley cropping, green manuring, crop rotation and agro forestry. Vegetable being short duration crop and having faster growth phases, the available organic matter needs to be properly composted. Vermicomposting can be followed for quicker usage of available organic matter in the soil and improving the soil moisture holding capacity.
The foliar application of nutrients during water stress conditions helps in the better growth by quick absorption of nutrients. The spraying of K and Ca induces drought tolerance in vegetable crops. Spraying of micronutrients and secondary nutrients improves crop yields and quality.
Drip irrigation has proved its superiority over other conventional method of irrigation, in Horticulture due to precise and direct application of water in root zone. A considerable saving in water, increased growth, development and yields of fruits and vegetables and control of weeds, saving in labour under drip irrigation are the added advantages. Drip irrigation can be adopted in fruit crops and also to all vegetable crops including closed spaced crops like onions and beans.The saving in water is to the tune of 30-50 % depending on the crop and season. Generally inline drip laterals having emitting point spaced at 30cm distance and emitting at the rate of 2LPH is selected for vegetable crops. In crops like chilli, brinjal, cauliflower and okra paired row planting is practiced and one drip lateral is used for two crop rows.
The following methods may be adopted under limited water conditions to save water:
- Water saving irrigation method
- Mulching Practices in Vegetable Production
Under limited water situations, water-saving irrigation methods like alternate furrow irrigation or widely spaced furrow irrigation and drip irrigation systems can be adopted. Studies conducted on methods of irrigation in capsicum, tomato, okra and cauliflower indicated that adopting alternate-furrow irrigation and widely-spaced furrow irrigation saved 35 to 40 per cent of irrigation water without adversely affecting yield.
The technique of covering the soil with natural crop residues or plastic films for soil and water conservation is called mulching. Mulching can be practiced in fruits and vegetable crops using crop residues and other organic material available in the farm. Recently plastic mulches have come into use due to the inherent advantages of efficient moisture conservation, weed suppression and maintenance of soil structure. Wide variety of vegetables can be successfully grown using mulches. In addition to soil and water conservation, improved yield and quality, suppression of weed growth , mulches can improve the use efficiency of applied fertilizer nutrients and also use of reflective mulches are likely to minimize the incidence of virus diseases. For vegetable production generally polyethylene mulch film of 30micron thick and 1 to 1.2 m width is used. Generally raised bed with drip irrigation system is followed while laying the mulch film.
To overcome the adverse effect of high temperature and dry winds, tall growing trees need to be planted all along the boundary of the farm. Inter cropping of vegetable crops of the area can be practiced in orchards during summer months. Maize/ Sorghum can be grown all along the border of the plot to mitigate the effect of desiccating winds.
In peri-urban regions where climate does not favour year round production of crops in the open field, vegetable production can be taken up in protected environment. Protective structure is a facility to protect crop from biotic and abiotic constraints. Structures for protected cultivation include green houses, plastic/net houses and “tunnels”. Commonly used protected structures are polyhouses and net or shade houses. Rain-shelter is a simple structure covered with polyethylene sheet which helps in producing the crops which are affected by excessive rainfall. The productivity of tomato, onions and melons are adversely affected in the event of high rainfall due to difficulty in managing the foliar diseases, lack of proper soil aeration and drainage and also depending on the nature of crop physical damage of the foliage and flower drop. Net house cultivation and shade net cultivation provide better microclimate especially during summer in minimizing the high temperature effect and improving the relative humidity. The productivity of tomato, French bean and capsicum can be improved during high temperature period by using net/shade net on the top.
For management of leaf miner spray neem soap 4 grams / liter or triazophos at the rate 1.5 ml / l. To manage mites spray Abanectin 0.5 ml/l. Aphids may be observed in case of beans. Spray neem soap (1.0 %) or neem seed kernel extract (4.00 %).
Do’s and Don’ts for Vegetable crops
- Establishing vegetation-free strips under the trees and between tree rows before growth begins.
- In crop like Onion, drum seeder may be used for direct sowing.
- Postpone transplanting of seedlings in the main field and also fertilizer application till the favorable soil moisture is prevailed.
- Once the soil moisture condition becomes favorable transplanting of the seedlings may be taken up.
- Resorting to foliar application of (water soluble) major nutrients.
- Protection of young plants with partial shade.
- In the inter spaces of crops weeding and inter-culture practices may be followed.
- Thinning may be taken up to reduce the plant population.
- Alternate furrow Irrigation may be taken up based on the availability of water.
- Drip Irrigation may be followed. Pitcher irrigation wherever drip is unavailable for protective maintenance.
- Plastic mulching and drip irrigation may be followed for better soil and moisture conservation and weed control.
- Adopting the conjunctive use of surface and ground water as well as the use of non-conventional sources such as brackish water.
- Waste water should not be utilized without pretreatment & safe reuse may be ensured.
- Minimise use of those fertilizers which promote vegetative growth like nitrogen, use K and B as foliar spray to maintain plant turgor.
- Reducing water losses during conveyance and distribution.
- Use of super absorbent polymers such as Luquasorb for water absorption and slow release.
Do’s and Don’ts for fruit crops
- In situ soil moisture conservation by trenching, contour/ field bunding, Gully Plugging, Loose boulder check dams may be taken up.
- Use locally available organic mulches to conserve moisture in situ in the basin. Adopt to drip/ trickle irrigation for judicious use of water. In situ grafting on drought resistant root stocks for better establishment of saplings. Practicing conservation horticulture such as inter crops and soil moisture conservation.
- Avoid soil application of fertilizers till sufficient soil moisture is available.
- Adopting to foliar nutrition of major nutrients under water stress conditions to enhance the nutrient uptake and use efficiency.
- Provide protective irrigation through pitcher and protective shade to young plants to reduce the high evaporative demand.
- In addition to drip irrigation and mulching for production of fruit crops under water limiting conditions, novel irrigation methods, like partial root zone drying (PRD), could be adapted in grapes, mango and citrus. The partial root zone drying method helps in development of a deeper root system.
- For all fruit crops, basin mulching with locally available plant material and plastic mulch may be taken up.
- Try to compost all the available plant waste materials and use it as organic manure to fruit and vegetable crops.
- For all the horticultural crops, drip Irrigation may be followed. Pitcher irrigation wherever drip is unavailable, is suitable for protective maintenance.
Source : NHM