Effects Of Salt On Growth And Distribution Of Cotton Root In Under-film Drip Irrigation

Scarce water resources and soil salinity are important limiting factors for agricultural production and environmental melioration in arid and semiarid regions. The under-film drip irrigation has gained widespread popularity as an efficient and economically viable irrigation method for increasing water use efficiency and reducing the adverse effects of salinity on plant growth and yield. This study focus on soil salinity management and saline water reuse and sets out to address the relationship between the soil salt and cotton root distributions, and the mechanisms for root growth compensatory effect.This study consisted of a pot experiment and a field experiment. The effect of three different soil salinity levels on growth and distribution of cotton root in under-film drip irrigation were studied with a pot experiments. A field experiment was conducted to evaluate the effect of saline water on distribution of cotton root under both surface and subsurface drip irrigation conditions. The main results and conclusions were listed as follows:Root dry weight of cotton reached the highest value at the boll stage and then decreased under low soil salinity level conditions, but increased with the cotton growing under higher soil salinity level conditions. The R/T ratio was decreased with soil salinity level increased. Root mainly distributed at 0-20 cm in soil profile, and very few roots were found at deeper layer in 1.12 and 1.90 dS m-1 treatments. For 0.32 dS m-1 treatment, Root mainly distributed at 0-30 cm in soil profile. The average root length density (RLD) was decreased with soil salinity level increased, but the average root diameter was increased. Cotton root absorption area was higher in higher salinity treatments than that in control.Water mainly distributed at 30-70 cm in soil profile under subsurface drip irrigation condition, and at 0-30 cm for surface drip irrigation. Soil salinity was increased with irrigation water salinity level increased. Soil salt built up at top 10-30 cm in surface drip irrigation and accumulated significantly at 80-100 cm in subsurface drip irrigation.Root dry weight, total length and total surface area were increased with irrigation water salinity level increased, but there no significant differences between surface and subsurface drip irrigation treatments.