Can planting date and cultivar selection improve resource use efficiency of cotton systems?

Water is an increasingly valuable resource and there is uncertainty about future rainfall patterns in a changing climate. Similarly, there are concerns with nitrogenous fertiliser use due to risks of greenhouse gas emissions and rising costs. Hence, it is timely to revisit and develop crop management strategies to balance economic, social and environmental impacts to determine if greater efficiencies can be attained. We investigated the potential to manipulate resource use efficiency with planting date and cultivar in cotton farming systems. Flexibility in planting date in some environments is now more practical because transgenic cotton provides better insect control, resulting in higher fruit retention and a shorter fruiting cycle. This allows later plantings to maintain yield and fibre quality. This is the first study to examine cotton planting date effect on resource use efficiency in Australia. Field experiments were conducted over two seasons at Narrabri, New South Wales, Australia (30°S, 150°E) to investigate the effect of delayed planting date and cultivar (differing in plant morphology and yield potential) on lint yield and quality, and resource use efficiency (water and nitrogen). Lint yield and resource use efficiency were not statistically decreased if planting occurred more than 30 days from the normal target planting date of 15 October. Studies using the OZCOT cotton crop simulation using 53 seasons of climate data confirmed the opportunity for improved water use efficiency with planting delayed to 15 November in warmer long-season Australian cotton regions.

► Planting date has potential to improve WUE, NUE without affecting yield or fibre quality.
► Yield, WUE and NUE are not decreased if planting delayed 30 days from 15 October.
► Simulations indicated better WUE if planting delayed to 15 November in long season areas.