Root Mass Distribution of Winter Wheat as Influenced by Different Tillage Systems in Semi Arid Region

Abstract

The effect of three tillage systems e.g. conventional (CT), minimum (MT) and no tillage (NT) systems on wheat root growth was studied in a silty clay loam soil under flood irrigation system in southwestern of Iran. Root length density and below ground biomass were determined at tillering and anthesis stages of whea t (Triticum aestivum L.) growth by soil core sampling and excavation. In tillering stage, root densities of 5-10, 10-20 and 0-30 cm soil depth were significantly different among tillage treatments. The difference was not significant for 0-5 and 20-30 cm depth. In anthesis stage, root densities were significantly different among tillage treatments for all soil layers except for the 20-30 cm depth. Although, the CT treatment resulted in a greater root length density and below ground biomass at tillering stage, the root length density and below ground biomass increased in MT compared to other tillage treatment at anthesis stage. The ratio of below ground biomass to above ground biomass was not significantly different among the tillage treatments. Although grain yield obtained in NT was about 500 kg ha greater than other tillage treatments, the differences 1 in grain yield, straw, leaf area index, 1000 grain weight and the seed harvest index among tillage treatments were not statistically significant. The results suggest that the inhibition of root growth by possibly mechanical impedance of soil can be declined in later stage of wheat growth and the reduced tillage system produce wheat root length density equivalent or even higher than the conventional tillage in a semiarid region.