Agriculture Reference
In-Depth Information
sensitive to drought stress at all stages of growth, responding to drought
with reduced growth and premature heading.
8.3.6.3
ROOT, TUBER, AND BULB VEGETABLE CROPS
In sweet potatoes, potatoes, carrots, and onions, yield depends on the pro-
duction and translocation of carbohydrates from the leaf to the root or
bulb. The most sensitive stage of growth generally occurs as these stor-
age organs enlarge. Carrots require an even and abundant supply of water
throughout the season. Stress causes small, woody, and poorly flavored
roots. Uneven irrigation can lead to misshapen or split roots in carrots,
second growth in potatoes, and early bulbing in onions.
8.3.6.4
FRUIT AND SEED VEGETABLE CROPS
Cucumbers, melons, pumpkins and squashes, lima beans, snap beans,
peas, peppers, sweet corn, and tomatoes are most sensitive to drought
stress at flowering and as fruits and seeds develop. Fruit set on these crops
can be seriously reduced if water becomes limited. An adequate supply of
water during the period of fruit enlargement can reduce the incidence of
fruit cracking and blossom-end rot in tomatoes. Irrigation is often reduced
as fruit and seed crops mature.
Plant growth stage also influences the susceptibility of crops to drought
stress. Irrigation is especially useful when establishing newly seeded or
transplanted crops. Irrigation after transplanting can significantly increase
the plant survival rate, especially when soil moisture is marginal and the
evapotranspiration rate is high. Irrigation can also increase the uniformity
of emergence and final stand of seeded crops. For seeded crops, reduce the
rate of application and the total amount of water applied to avoid crusting.
If crusting is present, use low application rates and small amounts of ir-
rigation water to soften the crust while seedlings are emerging.
8.3.6.5 SALINITY
Salinity is also a serious problem that reduces growth and productivity
of vegetable crops in many salt affected areas. Furthermore, it is estimat-
