ABSTRACT
Abstract ................................................................................................. 150 9.1 Introduction .................................................................................. 150 9.2 Responses of Physiological Traits Under Drought Stress ........... 155 9.3 Physiological Parameters Help in Screening Drought Resistant
Varieteies ...................................................................................... 157 9.4 Conclusion ................................................................................... 166 Keywords .............................................................................................. 167 References ............................................................................................. 167
A. CHATTERJEE1 and S. S. SOLANKEY2
ABSTRACT
Moisture stress is one of the greatest environmental factors reducing yield in arid and semiarid crops. Drought is often accompanied by relatively high temperatures, which promote evapotranspiration, (ET) and affects photosynthetic kinetics, thus intensifying the consequences of drought and further reducing crop yield. About two third of the geographical area of India receives low rainfall (less than 1000 mm), which is also characterized by uneven and erratic distribution. Out of net sown area of 140 million hectares about 68% is reported to be vulnerable to drought stress and about 50% of such vulnerable area is classified as ‘severe,’where frequency of drought is almost regular. Vegetables being succulent in nature, are sensitive to drought stress, particularly during flowering to seed development stage. Moreover, the legume vegetables, for instance cowpea, vegetable pea, Indian beans, etc., grown in arid and semiarid regions are generally affected by drought at the reproductive stage. Drought stress triggers drought tolerance mechanisms involving certain morphological, physiological and biochemical traits in vegetables, which are considered to be adaptive in nature. These traits are investigated thoroughly to serve as screening tools in developing drought resistance varieties with greater potential to maximize use of stored soil water and increased economic yield per unit water use. Starting from germination potential, shoot and root architecture and root anatomy, shoot and root fresh and dry weight ratio, total leaf area, stability to flowering processes are needed to be analyzed. Important physiological traits such as osmotic adjustment, cell membrane stability, (CMS), photosynthetic and transpiration rate, stomatal conductance, water use efficiency, (WUE) chlorophyll fluorescence parameters, photosynthetic pigment content, plant canopy temperature simultaneously with biochemical attributes including level of antioxidant enzymes, non enzymatic antioxidant and pyridine nucleotides involve in drought tolerance mechanism.
