the effects of two different deficit irrigation managements on the root length of maize

the response of root to water stress is one of the most important parameters for researchers. study of growth and distribution of root under different irrigation managements helpsresearchersto a better understanding of soil water content, and the availability of water and nutrition in water stress condition. to investigate the effects of four levels of irrigation under two different deficit irrigation managements on the root length of maize, a study was conducted in 2009. irrigation managements included fixed irrigation interval-variable irrigation depth (m1) and variable irrigation interval-fixed irrigation depth (m2). maize plants were planted in 120 large 110-liter containers in a strip-plot design in a randomized complete block with three replications. root data sampling was done after root washing in five growth stages. the results showed that the effect of irrigation levels on root length was significant (p<0.05) under both managements. the maximum root length was 4.61 and 4.64 km per m3 of soil profile in m1 and m2, respectively in the depth of 0-70 cm of soil profile which was observed in full irrigation treatment at milk stage. the results indicated that root length in mild-deficit-irrigation level was more than root length in moderate and mild-deficit-irrigation levels. the response of root maize to water stress was more severe in variable-irrigation-interval management and the same amount of reduction in applied water resulted in more decrease in root length under variable-irrigation-interval than fixed-irrigation-interval management. therefore, due to the importance of root length as one of the most important characteristics of growth indices in maize to determine the amount of water absorption, determination of the optimum level of water stress and selection of an appropriate deficit-irrigation management can increase water use efficiency as well as maize yield.