Crop Adaptation to a Fluctuating Environment Is a Matter of Density-Independence – a Case Study for Maize and Wheat.

Diverse agro-ecosystems imposed by the ongoing climate changes ought to supply more food to sustain an ever increasing global population. This work summarizes the findings of two review papers on stability of maize and wheat, pinpointing that inter-annual variation in optimum population might constitute an obstacle to obtain effective resource use and reach the season’s grain yield potential. In dry seasons small number of plants per area can survive and cultivation at lower populations is prudent. Instead, much higher populations are required to accomplish the grain yield potential of propitious seasons. In sequence, an appropriate population is hard to be established because the water regime of the growing season is not foreseeable at the sowing time. Hence, ineffective resource use results in harvested yield lagging substantially behind the potential yield, threatening crop sustainability and food adequacy. The problem is acute in maize, and indicatively, prediction of possible crop disaster in a dry season came true at the lower USA states during the 2012 summer. Even though less severe, it becomes apparent in wheat as well particularly at the Mediterranean-type environments. The root cause of largely varying optimum population is poor performance at the single-plant level. The remedy relies on prioritization of individual-plant performance targeting stabilization of optimum population at low levels, i.e. breeding of density-independent cultivars that perform well at a wide and of low threshold range of populations. Case studies are supporting that seeking among the currently available cultivars those that perform as fairly density-independent is a sound task. Further, experimental data are encouraging that the pursuit of breeding density-independent cultivars is a realistic goal.

 

Acknowledgement

Work co-financed by EU (ERDF) and Greek funds through the program code 09 SYN-22-604 "SYNERGASIA 2009 – Action I. Cooperative small- and mid-scale projects ".