Effects of subsurface drip irrigation and furrow irrigation management on growth variables and root distribution in sugarcane cultivation.

This study aimed in the 2017-2018 year to investigate the effect of subsurface drip irrigation on the volume of irrigation water, growth variables and root distribution for the sugarcane first ratoon. For this purpose, the management of subsurface drip irrigation with closed end furrow irrigation (as control) were studied. Three measurement plots/pilots were selected in each field. Number of plants, number of green leaves, leaf length and width over one meter were counted and measured six times at 91, 99, 105, 112, 119 and 128 days after harvesting of plant, respectively. The results showed that by applying the subsurface drip irrigation in sugarcane and its proper management, no matter the depth of application or the specific space of the emitters, on average about 31% will save on irrigation water. Number of Leaf and leaf length and leaf width were not significantly different in both irrigations. The number of stems and leaf area index in subsurface drip irrigation had significant difference with irrigation in levels of 95 and 99 percent, respectively. The mean of leaf area index in subsurface drip irrigation and furrow irrigation were 4.1 and 2.7, respectively, and this index, in the subsurface drip irrigation was 34% higher than the average of furrow irrigation. The active depth of preservative roots was up to 120 and 143 cm vertically and horizontally in subsurface drip irrigation and up to 100 and 104 cm in furrow irrigation, respectively. This indicates that the roots in subsurface drip irrigation are about 17% and 27% deeper and wider than furrow irrigation, and also were finer and deeper than the furrow irrigation. In subsurface and furrow drip irrigation, about 96% and 98% of the vertical roots, respectively, were propagated at a depth of 60 cm. Keywords: Leaf area index, Root extension, Sugarcane, Irrigation water, Sub-surface drip irrigation