Selection based on tolerance of wheat against terminal drought: Focus on grain yield at the presence of liquid humic fertilizer

One of the most important strategies for wheat breeding in Mediterranean climates is to produce irrigated wheat genotypes, which are potentially capable of growing to yield satisfactorily in spite of experiencing terminal drought. On the other hand, breeders can use humic preparations as an effective stimulus for plant breeding. These natural materials are the fruit of modern humate producing technology. As a result of this, 42 bread wheat genotypes were planted in the experimental farm of Islamic Azad University, Ardabil Branch, in the form of randomized complete blocks design in 2006 to 2007 farming year in order to evaluate their tolerance against terminal drought. Based on the results of this investigation focused on the mean grain yield, genotypes 2, 6, 11, 24, 25, 35, 36 and 38 were selected, and were compared by an in vitro experiment for early growth characters in particular for tolerance against drought at the presence of liquid humic fertilizer. Liquid humic fertilizer increased the tolerance of genotypes number 25, 35 and 36 in this stage of wheat growth. Another experiment was conducted on three genotypes numbered 22, 25 and 35 taken from previous experiments (both in vitro and in situ), together with three other genotypes (Ruzi-84, Gobustan and Saratovskaya-29) from Azerbaijan Republic in the form of factorial split plot based on randomized complete block design in 2009 to 2010. The factors included normal irrigation; normal irrigation + humic fertilizer; drought; drought + humic fertilizer. Generally, humic fertilizer increased the biological yield by 21% and grain yield by 22%. Application of humic fertilizer in drought condition put the mean grain yield in the same group as irrigation levels in drought condition. Compared to other genotypes, Gascogene showed the highest response to humic fertilizer (1 ton of grain) based on yield increase in terminal drought condition. It should be recommended that the application of humic fertilizers should aim at developing terminal drought tolerance in breeding programs.