Customized speed breeding as a potential tool to advance generation in wheat

In the context of the growing human population and climatic change, the current pace of wheat improvement is slow to meet future demand. This downturn partly owes to long generation time which demands technologies such as speed breeding (SB) that can accelerate plant growth and generation turnover. In field crops like wheat, SB is particularly contextual, because annual crop cycle is limited to one to two generations per year. To enable rapid generation advancement, SB uses extended photoperiod with supplementary lighting and temperature control to accelerate the development rate. However, if a part of these conditions is naturally available, such as temperature and humidity, SB can be launched with photoperiod manipulations alone. To test this hypothesis, we have conducted a study involving ten wheat cultivars, of which six were of Triticum aestivum and two each were of T. durum and T. dicoccum. The cultivars were subjected to 22 hours of extended light using red LED lamps and 2 hours of dark in a polyhouse, under natural temperature range of 17-22 degrees C and relative humidity of 75-80%. In all the cultivars, except HD 2967, plants reached heading in 36-42 days and physiological maturity in 67-73 days. In contrast, the same cultivars took 53-72 days for heading and 105-132 days for physiological maturity under field conditions. With SB, we could obtain five generations per year as against two generations under field conditions. Our results suggest that the customized SB has the potential for accelerated breeding as well as for integration with modern wheat improvement technologies.