Study On The Relationship Between The Effect Of Plant Modes On Root Growth Of Under-mulch-drip Irrigation And Soil Moisture

High planting density is an important way to increase yield of cotton in Xinjiang, and also the basic measure for other cotton-growing region of China. The reasonable mode of plant and row spacing under high planting density is not only favorable for cotton growth, but also an important method to combine with machinery management and cotton harvest. 5 kinds of plant modes (Da-sanmo, Ji-caimian, Xiao-sanmo, Deng-hangju and Suo-hangju) and 2 level water treatments (75% field water-holding capacity (θf) and 45%θf) were arranged with the condition of high planting density and drip irrigation. The character of water absorption, morphology, physiology, and shoot growth were measured during the whole cotton growth period. The content of soil water was monitored from water treatment stage to boll-opening stage. In this way, we analyzed the relationship between root-shoot growth and soil water content under different planting modes. The result showed that:1. Soil water content and root water consumption was comparatively stable in 0-60cm soil layer with 75%θf treatment, whereas it showed a larger oscillation and there existed heavy water stress with 45%θf treatment. The root water consumption of 45%θf treatment was significantly lower than that of 75%θf treatment. The root water consumption of Da-san-mo was significantly higher than that of other planting modes with 75%θf treatment, and root water consumption of Ji-caimian and Suo-hangju were relative lower with 45%θf treatment. Therefore, narrowing row space was help to increase drought resistance of root.2 .The root biomass, root length density , root surface area and root diameter increased in 0-40cm soil layer after reducing row spacing, whereas the root diameter, root length, root surface area showed decrease in 40-80cm soil layer. The root distribution ratio decreased with row space reduced in 0-40cm soil layer with 45%θf treatment, and drought stress could be resisted by more distribution of the lower root system. Therefore, narrowing row space would help to increase water using efficiency with 75%θf treatment.3. Root vigor with 75%θf treatment was higher than that of 45%θf treatment, while the content of soluble protein, SOD, POD and MDA with 75%θf treatment were lower than that of 45%θf treatment. Root vigor and the content of soluble protein, SOD and POD with 75%θf treatment of Xiao-sanmo arrangement were higher than that of other planting modes in 0-80cm soil layer; while the content of MDA with 45%θf treatment of Da-sanmo was higher than that of other planting modes.4. LAI improved with the content of soil water increased. LAI with 75%θf treatment was higher than that of 45%θf treatment. The values of LAI, dry matter per plant and reproduction organ of Xiao-sanmo were higher than that of other planting modes with 75%θf treatment. The cumulative rate of dry matter per plant of Da-sanmo was the highest and dry matter of reproduction organ of Deng-hangju was the highest with 45%θf treatment. The average leaf angle improved gradually and the capability of light interception increased with row spacing reduced. The capability of light interception with 75%θf treatment was higher than that of 45%θf treatment.5. The number of boll per plant, single boll weight and yield were higher than that of other planting modes with 75%θf treatment of Xiao-sanmo. The yield of Deng-hangju was the highest with 45%θf treatment, and followed by Suo-hangju and Ji-caimian. It suggested that narrowing row space would help to increase yield under the condition of water shortage.