Control of Water Stress

Water stress reduces the rate of photosynthesis in plants. In soybean crops, water stress leads to a loss of root integrity. The failure of the lower leaves to intercept light in a mature crop is compounded by the water-related limitations. The result is that lower leaves abscise and, because seed pods (yield) are supplied with assimilate mainly from leaves at the same nodal position on the stem, they in turn are lost and overall yield is reduced. The control of water stress in crops is a major PGR target in yield maintenance. The alleviation of water stress in developing crops, particularly in arid areas, is also desirable. 

Most terrestrial plants experience daily periods of water stress that are detrimental to growth and development. Where water demand outstrips supply the type of crops able to be cultivated is severely limited. Therefore, there is a considerable need to devise methods to reduce water loss from crops by transpiration. 

The physiology of stomatal movement has been extensively researched. Early studies using phenylmercuric acetate demonstrated that the induced closure of stomata could conserve water significantly up to one month from the time of treatment. Although reductions in transpiration would probably carry a yield penalty, the long-term benefits of increased land use are desirable. However, no commercially viable anti-transpirants have been produced. 

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