| How to improve the valuable water use efficiency is great challenge for both agronomists and plant biologists. Numerous strategies for saving the water use efficiency (WUE) have been proposed and tested in the field. One of the great proposals for developing the potential of plants for maximizing water transpiration efficiency was the alternative irrigating the roots during their growing stages. This experiment was performed at agriculture water and soil environmental field science research station of farmland Irrigation Research Institute, the Chinese Academy of Agricultural Sciences in 2008. Regulation technique of integrity irrigation was established by combining the growth characteristics of potato with patterns of irrigation and quantity of irrigation to control the use of water forwardly. Variation of soil water transfer, root growth and distribution of potato, physiology and ecology effect, yield and water use efficiency as well as effect of potato-soil interaction on environment nutrient situation were determined to study the influence of partial root dry irrigation (PRD) on potato growth and its water saving effect. The main results were summarized as below:Potato yield of furrow partial root drying (FPRD) was 3.1% lower than conventional furrow irrigation (FI) while no significant difference was found between subsurface partial root drying (SPRD) and conventional subsurface irrigation (SI). Yield of SPRD was 7.7% higher than FPRD. Compared with FI, SI especially SPRD can significantly improve potato yield by saving 30% water.WUE and WUEet (the use efficiency of water including irrigated water and rainfall) of PRD were significantly higher than RI. WUE and WUEet of SPRD was 28.2% and 10.2% higher than RI, respectively; WUE and WUEet of FPRD was 25.8% and 8.7% higher than RI, respectively; WUE and WUEet of SPRD was 35.6% and 33.5% higher than FPRD, respectively; WUE and WUEet of SI was 33.1% and 31.2% significant higher than FI.The content of crude protein and titratable acid of SPRD were 4.17% and 2.75% higher than RI, respectively; for FPRD,4.35% and 2.08% were higher than RI, respectively; for SPRD,1.19% and 4.17% were higher than FI. SI and FI can increase content of vitamin C and starch but was not significant. Content of starch and titratable acid of PRD were 4.17% and 8.70% higher than RI, respectively and this was propitious to improve nutritional quality of potato tuber. Reduce sugar content of SPRD was 14.6% lower than RI and significant difference was found between treatments. Potato tuber quality was improved under PRD, especially for SPRD.Water content of 0-60 cm soil layer was ascends and descends alternately during the potato growth stage. Irrigation side of PRD treatment had higher water content than RI. Different position of RI maintained upper level water content while furrow water content was highest, and then was slope and ridge was lowest for PRD during whole growth stage of potato.Effect of PRD on distribution of potato root was present radial; root density was highest for plant center and decreased gradually towards different direction. Root length density of SPRD treatment was higher than RI, except for the ridge spinal where potato sowed and 45 cm hereinbefore of emitter. Root of FI treatment was concentrated in 0-45 cm soil layer,45 cm hereinafter was lower. Distribution of root weight density was the same as root length density.Leaf area and dry matter were increasing gradually with potato growth and leaf area was decreased when maturation. Leaf area of SI and RI was higher than FI and PRD, respectively, and significant difference was found between different treatments. Dry matter of SI was higher than corresponding FI and RI was higher than PRD under the same irrigation level. Average growth rate of dry matter for each treatment were SPRD 34.55%, SI 34.78%, FPRD 32.77% and FI 31.75%, no significant difference was found. Root-shoot ratio of PRD was higher than RI under the same irrigation mode, and generally, root-shoot ratio of SI was higher than FI at the same stage.Variation of photosynthetic rate, transpiration rate and stomata conductance was consistent under different irrigation treatments, Photosynthetic rate, transpiration rate and stomata conductance were decreased with potato growth and SPRD and FPRD treatment was lower than RI and SI and no significant difference was found for photosynthetic rate while difference of transpiration rate and stomata conductance were significant. PRD treatment can reduce the loss of water from potato plant and improve the water use efficiency. NO3-- N content in leaf was increasing first and then decreased with potato growing. Leaf NO3--N content of SPRD and FPRD was higher than FI and SI. For whole plant, total N content of SI and FI was 2.03% and 0.86% lower than PRD, respectively. For potato tuber, total N content of SPRD and FPRD was 2.80% and 2.31% higher than RI, respectively, and SI was lower than FI. Trends of soil total N content was the same between different treatments. Topsoil had highest total N content and decreased with increasing depth. Total N content of SI and RI was higher than FI and PRD under the same depth, respectively.Both SI and PRD caused the variation of soil salinity. EC (electrical conductivity) was highest from surface to ridge spinal (25 cm) of SI and decreased gradually with increasing soil depth. Distribution of EC in topsoil from high to low was followed by slope, spinal and ridge. EC of SPRD was highest in the position potato sowed and spinal, slope was lower than spinal, and ridge was lowest. EC was highest in topsoil under the same level(y=0, y=18.5 and y=37.5) and decreased with increasing soil depth.Taken together, the experiments from potato field demonstrated that alternative irrigating the partial roots in comparison to the uniform irrigation of whole root system could stimulate the root development for maximizing the available water use in the soils. This technique demonstrates the perspective of application in the agriculture field. |
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