Russell E. Mullen

Drought Stress Effect on Crop Pollination, Seed Set, Yield and Quality

The effect of drought stress on crop growth and yield has become more common worldwide in the last two decades. The reproductive stage is the most critical stage for drought stress during crop growth, because it strongly impacts yield and seed quality. Improving crop growth and yield under drought is thus a major goal of plant breeding. Drought stress negatively affects flower pollination by decreasing the amount of viable pollen grain, increasing the unattractiveness of flowers to pollinators, and decreasing the amount of nectar produced by flowers. Consequently crop seed set is lowered. Moreover, drought stress affects crop yield by reducing grain yield and all yield components. The correlation is clear between crop pollination, seed set and yield. Drought stress not only affects seed production, but also affects seed quality such as germination and vigor tests. In this chapter we review the currently available information on pollination, yield, and yield components and seed quality under drought. We give an outlook towards the physiological and biochemical processes involved in the reduction of crop yield in response to drought stress at the reproductive stage. We focus on physiological processes of plant reproductive organs in response to drought stress at anthesis and the attractiveness of the flowers to pollinators. Here we help plant breeders to select drought tolerant traits by understanding the correlations between pollination, yield, yield components and seed quality under drought stress at reproductive stage and to explain how drought stress effects final yield and seed quality during this stage.

Pod production of Prosopis juliflora (Sw.) DC. as affected by supplementary and honeybee pollination under arid conditions

Abstract An experiment was conducted to examine the importance of honeybees and flowering dates for pollination and pod characteristics of Prosopis juliflora grown under semiarid conditions. Flowers of Prosopis were subjected to two pollination treatments: 1) open pollination and 2) supplementary pollination at different flowering dates from September to January. Number of racemes per node, number of flowers per raceme, pod per raceme, pod length and weight, seed number per pod, 100-seed weight, and total seed yield per node were measured. Prosopis trees produced an average of 6 racemes per node. Supplementary pollinated flowers had higher pod number/raceme but lower pod length and weight in comparison with open pollinated at all flowering dates except for January. Pollination treatment did not influence seed number or characteristics. These data suggest that although supplementary pollination increased pod set per raceme, bee pollination gave the same pollination efficiency and better pod quality.