Characteristics Of Drought Resistant Plants
1. Early closure or stomata:
Opening stomata for short time in easy morning & remained closed during rest of day when moisture stress is minimum with photosynthesis with the least loss of water e.g. varieties of wheat, oats.
2. Increased photosynthetic efficiency:
The plant species using the pathways have a high rate or carbohydrate assimilation for given stomatal opening higher temperature & light optimum e.g. maize sorghum.
3. Low rate of cuticular transpiration:
Thick cuticle results in low rate in transpiration e.g. cactus.
4. Deposits of lipid layers:
On exposure to moderate drought conditions the lipids are deposited on leaf surface which in reduction transpiration losses e.g. soybean
5. Reduction in leaf area:
Rolling or curling of the leaves reduces the leaf surface exposed to sunlight thus helps in reducing the transpiration loss under stress conditions. E.g. Maize, Sorghum, grasses etc.
6. Waxy leaf surface:
The leaf surface becomes waxy forming thick cuticle and develops spines on leaves which help in reducing transpiration losses. Eg. Safflower.
7. Stomatal frequency and location:
Location of stomata in cavity or in depressions of leaves reduces the direct contact of stomata with wind currents & reduces the transpiration losses. In drought resistant plants, the number of stomata found more a lower leaf surface. Similarly, the number of stomata is also reduced which helps in reducing transpiration losses.
8. Effect of awns:
The Awned varieties of wheat barley etc. can thrive well under stress conditions as the awns contain chloroplasts & stomata & can continue photosynthetic activities even when the stomata on leaves get closed during day time.
9. Accelerating water uptake:
The water uptake by plants in increased efficiently due to following plant characteristics.
i) Efficient root system:
i) Extensive root system
ii) Deeper root system
iii) Secondary root etc.
iv) Ability of roots to go towards available water
v) Ability of roots to penetrate in soil
ii) High root to top ratio:
1. Transpiring surface is reduced.
2. Water absorbing surface is increased.
3. High osmotic pressure: Under stress conditions the osmotic (Low osmotic potential) potential in roots and aboveground plant parts in reduced resulting increased water movement through soil and plant.
10. Nature of varieties suitable for Rainfed farming:
1. Varieties should have medium height with early grand growth period. e.g. rabi sorghum varieties – Selection – 3. SFV – 86, M -35 – 1.
2. Varieties should have medium tillering habit, bigger ear head size & bold grain size. E.g. bajara variety – shraddha.
3. The variety should have deep and extensive root system.
4. The variety should be of shorter duration.
5. The variety should have High Harvest Index.
6. The intercrop varieties should be of longer duration with differentiation growth habit. E.g. Red gram varieties BDN – 2, No. 148.
7. Varieties should be resistant to moisture stress.
8. Varieties should have coating either with wax or other material which prevent the loss of moisture through evaporation from stem and leaves. E.g. Rabi sorghum varieties – white glumes on stem & leaf sheath. Safflower varieties – waxy surface & spines on leaves.
9. The varieties should be photo and thermo insensitive e.g. Gr. nut variety – TAG – 24.