WHEAT RESPONSE TO NITROGEN AND POST-ANTHESIS WATER DEFICIT

Abstract

Relationship between post anthesis water deficit and nitrogen on wheat (Triticum aestivum L.) in Southern of Iran are not well defined. Therefore, we established an experiment on a clay loam at Shiraz Agricultural Researches Station, between 2006 and 2008. Three wheat cultivars were grown under post anthesis water deficit and three N fertilizers. Two-year average data showed that spike number per square meter and kernel per spike was similar at both nonstressed and post anthesis water deficit treatments. Kernel weight was reduced by water stress under 0 and 80 kg N ha, but increased under 160 Kg N ha. Under water deficit grain yield was reduced by 25%. Grain yield of the crop that no received N being 15% greater than for that receiving 80 kg N ha. Chamran produced the highest grain yield, which was 19% higher than that of Shiraz and Marvdasht. In water deficit treatment, straw yields increased with 80 kg ha increment of N but further increments of N had little effect. Under post anthesis water deficit DM remobilization efficiency increased with 80 kg ha increment of N by 29%, but further increments of N decreased it. The contribution of DM remobilization to the grain ranged from 7 to 23% of grain dry weight and under water deficit was 78% more than nonstress treatment. It is concluded that there is great potential to increase winter wheat yield by properly managing nitrogen fertilization in this region. Stored carbohydrate represented an important buffer for yield production when stress occurred during grain filling.