Research On Regulation Of Various Water-Nutrients On Root System Of Cotton To Promote Water-Nutrient Use Efficiency

There is a need to explore a new technique for increasing yield and enhancing water-nutrient use efficiency in cotton production system.An experiment was conducted at the experimental farm of Shihezi University in 2015 and 2016 growing seasons.With cotton cultivar Xinluzao 45 and two irrigation regimes(no-deep layer water application?W₀?and deep layer water application(W₈₀)).Surface basal fertilizer(F₁₀)and deep basal fertilizer?F30?were also applied to individual irrigation treatment to assess the effects of water-nutrient application method on the distribution of moisture and nutrient in the soil,root morphology and physiological activity,agronomic traits,dry matter production and water-nutrient use efficiency,and to analyze the relationship between root characters with aerial parts of a cotton plant to adjust dry matter production and water-nutrient use efficiency.The main results are as follows: 1.Soil moisture and nutrient content in response to deep layer water and basal fertilizer application.The soil moisture content in 0-40 cm soil layer in W₈₀ treatment had no significantly difference with W₀ treatments.Available nitrogen,phosphorus and potassium in 0-50 cm soil layer in W₈₀ treatment was significantly higher than compared with W₀.Soil moisture and nutrient content for W₈₀ had higher value than that of W₀ treatment in the 50-120 cm soil profile.The soil moisture and nutrient content in F₁₀ resulted in lower value compared with F30 treatments in 0-30 cm soil layer.In W₈₀ treatment,the soil moisture content in whole soil layer for F₁₀ treatment had no significant difference with F30 treatment,but F₁₀ has a lower soil nutrient content in 0-30 cm and 60-80 cm soil layer compared with F30 treatment.2.Root morphological characters and physiological activity as influenced by the application of deep layer water and basal fertilizer application.Cotton root morphological attributes?root length,root surface area and root mass?and physiological activity?root vigor,root nitrate reductase and acid phosphatase?was higher in W₈₀ treatment compared with W₀ treatment in 0-40 cm soil layer.In addition,the root morphological traits were reduced W₀ treatment but the physiologicval activity was higher compared with W₈₀ treatment in 60-120 cm soil layer.In W₈₀ or W₀ treatment,the root morphological traits and physiological activity in 0-30 cm soil layer were higher relative to F30 treatment prior to 84 DAE.3.The effect of the couple of deep layer water and basal fertilizer application on aerial part growth.Comparing W₀ treatments,the bud stage and boll stage in W₈₀ treatments respectively prolonged by 2-7 d and 8-4d,and increasing the buds,fruit branches,follows and bolls;in W₀ or W₈₀ treatments,F₁₀ treatment prolonged the bud stage and boll stage,and increasing the buds,fruit branches,follows and bolls.In addition,photosynthetic ability?leaf area,chlorophyll and leaf gas change?and light energy conversion and utilization efficiency [maximal PSII efficiency?Fv/Fm?,effective quantum yield of PSII?YII?and PSI?YI?,electron transport rate of PSII?ETRII?and PSI?ETRI?] in W₈₀ treatments were significantly greater than that in W₀ treatments.In W₀ or W₈₀ treatments,photosynthetic ability and light energy conversion and utilization efficiency respectively in F₁₀ treatment were higher by 0.9-5.7% and 0.2-3.7% than that in F30 treatment.4.Impacts of deep layer water and basal fertilizer application on coordination and productive capacity between root and aerial plant parts.The ratio of effective root length,leaf area and root shoot ratio in W₈₀ treatment were significantly lower compared with W₀ treatment.In W₀F₁₀ treatment had lower ratio of the effective root length,leaf area and root shoot ratio but higher productive capacity of the effective root length and leaf area.In W₈₀ treatment,the ratio of effective root length and root shoot ratio in F₁₀ treatment were 6.2-19.4% and 16.3-88.3%,lower respectively.While productive capacity of the effective root length and leaf area were higher by 1.2-9.8% compared with F30 treatment.5.Influence of deep layer water and basal fertilizer application on dry matter production and distribution of cotton.Vegetaive?leaf and stem?and reproductive?bud and boll?structures dry matter production was greater in W₈₀ relative to W₀ treatment.In W₀ treatment,F₁₀ treatment had higher dry matter,vegetative and reproductive organ dry matter partitioning ratio and both maximum and average biomass accumulation rate compared with F30 treatment.In W₈₀ treatment,the value of the dry matter and the partitioning ratio of vegetative and reproductive organ in F₁₀ treatment was 8.0-14.9%,higher respectively.Maximum and average biomass accumulation rates of different organ were increased by 10.0% and 14.0% compared with F30 treatment.6.The effect of the couple of deep layer water and basal fertilizer application on water-nutrient use efficiency.In comparasion to W₀ treatment,water consumption rate was increased by 2.3% and nutrient?nitrogen,phosphorus and potassium?use efficiency of vegetative and reproductive organs were increased in W₈₀ treatment.In W₀ treatment,F₁₀ treatment had higher value of water consumption rate and ratio,nutrient use efficiency of different organs was increased by 14.0-16.0%.In W₈₀ treatment,compared with F30,water consumption rate and ratio in F₁₀ treatment were decreased by 1.5% and 16.4%,while nutrient use efficiency of different organs in F₁₀ treatment was increased by 10.7-15.2%.The present study proved that,deep layer water combined with basal fertilizer surface fertilization significantly increased cotton root distribution and physiological activity in the surface soil layer and root physiological activity in deep soil layer.This phenomenon promoted water uptake from fertigation and deep layer water.This increased the root and leaf productive ability and coordination between root and leaf which promoted the allocation of dry matter to reproductive organs after full flowering stage,decreasing the ineffective consumption of water and nutrient.Our data suggest that deep layer water and basal surface fertilization have the potential to increase water-nutrient use efficiency ultimately increasing cotton production in an arid region.