Efficacy of delayed fruiting in improving drought tolerance of cotton (Gossypium hirsutum. L.) In Georgia

Abstract

The development of cotton is a changing balancing act. Improving episodic drought tolerance of cotton by modifying cotton growth and development is the basis of this research. Delayed initiation of fruiting was investigated to determine if it is a possible mechanism to improve drought tolerance in cotton. To this end, two studies were conducted. A two year study conducted under a rainout shelter at the University of Georgia Experiment Station, Tifton, investigated the impact of fruiting branch removal (delayed fruiting) on cotton root growth and yield under irrigated and water deficit conditions. Delayed fruiting, irrespective of the irrigation treatment, led to significantly higher root counts. Delayed fruiting delayed maturity and also altered the yield distribution on the plant. In 2000 delayed fruiting under water stress reduced yield whereas in 2001 no such differences were detected. Thus delayed fruiting did result in increased root growth but did not enhance drought tolerance as determined by boll number or seed cotton yield. The second study examined the effect of early season flower bud removal on the whole plant CO2 exchange rate of cotton. The effect of flower bud removal on the CO2 exchange rates of cotton was investigated in a 31-day study conducted in a controlled environment whole plant assimilation chamber. No significant differences in the net photosynthesis, dark respiration, and daily carbon gain and carbon use efficiency were found in this study with flower bud removal. The selected photosynthetic parameters increased steadily with time for both the flower bud removal and the no flower bud removal treatment. However, the rate of increase (or decrease in dark respiration) was greater with flower bud removal for these parameters with their maxima (peak) occurring later in the study period.