| Aiming resource status of drought and water shortage and characteristics of planting in northwest arid area, the corn straw mulching experiment research on watermelon in dryland carried out from March to August,2011in agriculture research and demonstration bases of sheepfold village of martial arts town in Northwest A&F University. By setting up three different mulching patterns of whole surface mulch(WM). series mulch(SM) and root domain mulch(RM) and two different cultivation patterns of ridge and level plot. In order to provide the theoretical basis for straw mulch cultivation technology of horticultural crops in northern dryland, effects of different spatial straw mulch on soil moisture of0-120cm soil layer, soil temperature of5-25cm soil layer, soil nutrients of0-60cm soil layer, photosynthetic of watermelon, growth, yield and quality. The main findings are as follows:1. Planting watermelon with straw mulching is proved to be good for increasing soil moisture. All straw mulch treatments enhanced total soil water storage of0-120cm soil layer. WM treatment’s margin of increase was the largest, followed by the RM and SM treatment. At flowering and fruit-setting and Pre-swelling, differences among all straw mulch treatments’ soil water storage of root domain and between watermelon lines compared with CK were highest. Soil water storage of all straw mulch treatments at flowering were higher than CK significantly (P<0.05). Under ridging of cultivation patterns. margin of increase among all mulch treatments in root domain and between watermelon lines were respectively29.9-41.6mm and33.6-48.0mm. Under level plot of cultivation patterns, margin of increase among all mulch treatments in root domain and between watermelon lines were respectively27.8-41.5mm and20.6-39.lmm. At Pre-swelling. margin of increase among all mulch treatments in root domain and between watermelon lines under ridging of cultivation patterns were respectively17.6-54.8mm and26.0-37.8mm. Soil water storage between watermelon lines under level plot of cultivation patterns were no significant difference. but soil water storage in root domain was higher than CK significantly. the margin of increase was25.4-35.9mm. During all growth stages of watermelon. effects of all straw mulching treatments on soil moisture of0-120cm soil layer were differences. At flowering and fruit-setting.soil moisture’s margin of increase ridging with WM, SM and RM treatments compared to CK increased by20.0%,17.5%and15.2%(P<0.05) respectively, and level plot increased by35.7%,28.8%and34.9%(P<0.05). At swelling, soil moisture’s margin of increase ridging with WM, SM and RM treatments compared to CK increased by21.1%,17.6%and20.3%(P <0.05), and level plot increased by33.9%,15.9%and19.1%(P<0.05)2. All straw mulch treatments varing degrees lowered soil temperature of5-25cm soil layer between seeding and growing tendril. The decline of SM treatment watermelon root domain was the smallest, while the decline of RM treatment watermelon root domain was the smallest, and the decline of soil temperature became small gradually with the deepen of soil layer. The soil temperature’s speak in5-10cm soil layer was at14:00. Afterwards, the soil temperature of all straw mulch treatments began to reduce, while soil temperature in15-25cm soil layer had been in a slow rise and the peak delayed to20:00. At seeding of watermelon, soil temperature of all straw mulch treatments were lower than CK significantly, the average soil temperature per day’s decline of all straw mulch treatments were0.7-4.1℃. With the growth stage going, watermelon entered Pre-growing tendril, the low-temperature effect of all straw mulch treatments present substantial downward trend with vine of watermelon covering the surface with large area. The average soil temperature per day’s decline of all straw mulch treatments at Pre-growing tendril reduced to0.6-2.9℃. At Post-growing tendril, the decline was0.1-2.7℃. Until flowering of watermelon, there was no obvious difference between all straw mulch treatments and CK. All straw mulch treatments of ridge enhanced soil temperature of watermelon compared with all straw mulch treatments of level plot, especially this effect of increasing in root domain of watermelon more notable.3. Ridge and level plot with all straw mulching treatments increased the contents of soil available nitrogen, available phosphorus and available potassium in0-60cm soil layer after harvesting watermelons. And available nutrient contents with all straw mulch treatments of ridge in each soil layer were higher than the corresponding soil layer’s contents compared to all straw mulch treatments of level plot. Effects of all straw mulch treatments on all available nutrients were different. Changes of available phosphorus were the smallest. and changes of surface nutrient were the highest. The effects became small gradually with the soil layer deepen. All straw mulch treatments’ available phosphorus contents in different soil layer of root domain and lines were lower than available nitrogen and available potassium contents and the margin of increase also was significantly lower than available nitrogen and available potassium.4. Increase in coverage compared with CK, the highest SPAD value in WM treatment of ridge. Pn and Tr of all straw mulching treatments:RM treatment was the highest in margin of increase; WM treatment of ridge and level plot were the highest in Ci’s margin of increase. All straw mulching treatments decreased leaf temperature compared with CK, and RM treatment of ridge and WM treatment of level plot were the highest in decline.5. Effects of all straw mulch treatments on agronomic traits:At growing tendril, all straw mulching treatments lowered main vine length, number of leaves and leaf area. At flowering and fruit-setting, straw mulching treatments enhanced main vine and other indicators varing degrees. Margin of increase of all straw mulch treatments ’s fruit traits(longitudinal diameter, diameter and volume) was little, and all straw mulch treatments enhanced biomass (root fresh weight, stem and leaf fresh weight and fruit fresh weight) of watermelon at Maturity compared with CK. All straw mulch treatments increased significantly yield and water use efficiency of watermelon (P<0.05), and margin of increase of WM treatment was highest. The margin of increase of all straw mulch treatments’yield and water use efficiency were respectively24.8%-47.0%,42.7%-92.0%and13.6%-22.4%compared with CK. WM treatment of ridge and level plot increased soluble solids content (P<0.05) in middle and edge of fruit flesh which made quality of watermelon enhance significantly.6. WM treatment of ridge can improve soil moisture, soil temperature, available nutrient contents, photosynthetic parameters, yield, quality, and water use efficiency which is the appropriate mode of mulch cultivation of watermelon in dryland. |
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