Water Management in Horticultural Crops (1+1)

Critical stages of crop growth

• Optimal soil moisture for plant growth varies with the stage of crop growth. Certain periods during the crop growth and development are most sensitive to soil moisture stress compared with other. These periods are known as moisture sensitive periods. The term critical period is commonly used to define the stage of growth when plants are most sensitive to shortage of water. Inadequate water supply during moisture sensitive periods will irrevocably reduce the yield and provision of adequate water and other management practices at other growth stages will not help in recovering the yield lost.
• In case of vegetables, when they are young, though transpire less water, need a stress free moisture condition because of the very weak root system which is sparsely distributed and located in upper 15 to 20 cm layer of soil that gets quickly dried. Vegetable crops utilize and transpire more water in the later stages of growth during which moisture stress markedly reduces yield.
Critical soil moisture periods of crops

Crop	Available soil moisture (%)	Critical soil moisture stage of crops
Chillies	50	Tenth leaf to Flowering and fruit development and after periodical harvests
Potato	65	Stolon formation, Tuberization and tuber enlargement
Onion	60	Bulb formation and bulb enlargement
Tomato	60	Flowering and fruit development and each harvest
Peas	40	Flowering and pod development
Cabbage	60	Head formation and enlargement
Cauliflower	70	Curd formation and enlargement
Brinjal	50	Flowering and fruit development and after each harvest
Cucumber	50	Flowering and fruit development
Bhendi	45	Flowering and pod development
Leaf vegetables	70	Entire crop duration
Fruit crops	For fruit crops 50% Available soil moisture is taken as critical limit
Citrus		Flowering, fruit setting, fruit growth
Banana		Early vegetative period flowering and fruit formation
Mango		Start of fruiting to maurity
Pine apple		Vegetative growth
Grape		Vegetative growth. Frequent irrigation during vegetative stage may cause rotting of friuts
Guava		Period of fruit growth
Ber		A drought resistant plant ; irrigation is required during fruit growth


• All the stages of growth is equally sensitive to soil moisture stress for crops where vegetative parts are of economic importance. Total growth and yield of perennial plants are the summation of effects of stress at each growth stage. However, adequate water supply is essential at flower bud initiation, flowering and fruit set. Flower bud formation, however, increase due to restricted water supply prior to flower bud initiation in the case of citrus and mango.
• For realizing maximum benefit from the scarce irrigation water, irrigation is to be scheduled at moisture sensitive periods by withholding irrigations at other periods of lesser sensitivity. Such irrigation schedules along with improved practices increase the water-use efficiency in crop production.