Sustaining wheat yields with crop management in heat stressed environments : effect of organic and inorganic fertilizers, mulching, and irrigation frequency

Abstract

Wheat (Triticum aestivum (L.) emend. Thell) yield reduction associated with heat strees is a worldwide problem. The objectives of this research were to (i) to determine effects of major crop management factors on performance under heat stress and (ii) observe expression of morphological and physiological traits in response to inputs. Field experiments were conducted in Bangladesh, Sudan, and Mexico to determine the response of wheat performance to levels of crop management above those normally recommended by the perspective national programs. These included additional (i) irrigation, (ii) inorganic fertilizer (NPK), (iii) organic fertilizer in the form of farm yard manure (FYM), and (iv) straw mulch. In comparison to recommended management practices, addition of organic fertilizers resulted in the highest yield response (14%), and elevated levels of inorganic fertilizer the lowest (6%), When average across all environments. In Bangladesh, a hot humid environment, application of FYM raised yields by 24% in comparison to 16% when equivalent extra N was added in inorganic form, while there was no response to extra irrigation. In Sudan, a hot low relative humidity (RH) environment, extra irrigation resulted in substancial yield increases (68%), and the application of straw mulch was also beneficial. In Mexico, also a hot low RH environment where heat stress was modified by altering planting date, the effects of extra nutrition and straw mulch were generally more beneficial under hotter late sown conditions than with the normal sowing date. Traits generally responding to management included stand establisment, plant height, grain m-2, and total biomass, and in Mexico, chlorophyll content of flag leaves, canopy light interception, and canopy temperature depression, with FYM and mulch having the largest effects. Significant interactions among management factors are discussed.