| Two kinds of drip irrigation modes were set in this study in 2013. The first one was one-time drip irrigation and 3 treatments were conducted, respectively. The irrigation volumes were 20 mm, 40 mm and 60 mm respectively all at once at the fifth day of pod filling stage.Another was fractionated drip irrigations, 3 treatments was set. The total irrigation volumes were 20 mm, 40 mm and 60 mm at the fifth, twelfth and nineteenth day of pod filling stage respectively. In 2014, drip irrigations based on measurement of soil moisture content were conducted and 4 treatments were set, leading to different irrigation periods and irrigation volumes. The irrigation modes were 5mm, 10 mm, 15 mm and 20 mm respectively. When the soil moisture content dropped to 50%, next drip irrigation was conducted. We measured soil moisture dynamics, relevant physiological and biochemical indexes during and after drip irrigation periods. At mature stage, yield and yield components were measured according to the plots.1 The effects of different drip irrigation modes and different drip irrigation quantities on soil moisture contentWhen the drip irrigation quantity was 20 mm under one-time drip irrigation treatment, it had great influence on moisture content of 0-40 cm soil layer. Both 40 mm and 60 mm irrigation quantities under one-time drip irrigation treatment had great influence on soil moisture content of 40-60 cm. In the treatment 20 mm, 40 mm and 60 mm, the moisture contents of 0-20 cm soil layer were bigger on the first day after drip irrigations. While the soil moisture contents of 0-20 cm soil layer in each treatment dropped rapidly on the 8th day after drip irrigations and soil moisture contents were below lower layer soils. On the 15 th day after drip irrigations the soil moisture content of 0-20 cm didn’t appear to be much difference and the moisture content of lower layer soils was bigger. When drip irrigation quantities were40 mm and 60 mm under one-time drip irrigation treatment, the soil moisture contents in lowerlayer soils were bigger.After 5 days fractionated drip irrigation treatment, it had great impact on the soil moisture content of 0-40 cm layer in each treatment. Under fractionated drip irrigation treatments when the drip irrigation quantity was 20 mm the moisture content of each soil layer decreased obviously with the increase of the processing time. Compared with one-time drip irrigation,fractionated drip irrigation mainly affected the upper soil moisture contents and fruiting layer soils always kept moist state.After treated by drip irrigations based on measurement of soil moisture content, the dynamic changes of soil moisture were that: the soil moisture content of each soil layer presented downtrend with the number of irrigation days increased. We began irrigation when the relatively soil moisture content was under 50%. Under the condition that there was no rain,we confirmed that drip irrigation quantities were 5mm、10mm、15mm、20mm and drip irrigation cycles were 4d、5d、7d and 8d, respectively by dynamic monitoring the soil moisture content.2 The effects of different drip irrigation modes and different drip irrigation quantities on photosynthetic characteristics and dry matter accumulations of peanut during pod filling stageUnder the treatment of one-time drip irrigation, the net photosynthetic rate of the same day increased along with the increase of the drip irrigation quantities. On the 17 th day and24 th day, the decline of the soil moisture content led to the decrease of Pn. With the increase of treatment time, the net photosynthetic rate presented a declining tendency under one-time drip irrigation control. Compared with the one-time drip irrigation, fractionated drip irrigations treatments could maintain the high net photosynthetic rate, leaves’ normal transpiration and photosynthesis function, promote photosynthesis assimilation and lay physiological basises for achieving high yields.Under both one-time drip irrigation and fractionated drip irrigations treatments, dry matter accumulation of leaves, stems and pods showed the trend of gradually increased with the increase of drip irrigation quantities. Influenced by continuous senescence, the distribution rate of dry matters to leaves decreased and the distribution rate to pods increased in each treatment. The distribution rate of dry matters to pods in fractionated drip irrigations treatment was larger than that in one-time drip irrigation. Fractionated drip irrigations treatments were more advantageous to the distribution of dry matters to the pods.Under the drip irrigations based on measurement of soil moisture content treatment, thedry matter accumulation per plant increased with the increase of drip irrigation quantities.When drip irrigation quantities were smaller, the distribution rates of dry matters to pods were bigger so that small drip irrigation quantities promoted the allocation of dry matters to the pods. While under big drip irrigation quantities treatment, the distribution rates of dry matters to pods decreased with the increase of drip irrigation quantities. The allocation of dry matters to pods, stems and leaves all increased, leading to allocation proportion to pods decreased.3The effects of different drip irrigation modes and different drip irrigation quantities on yieldsThe yields of one-time drip irrigation increased sharply, compared with the CK. The full pod weight, 100-pod weight and 100-kernel weight rose along with the drip irrigation quantities. The yield of 20 mm treatment added by 10.67%, while the yields of 40 mm and60mm were 4.1% and 4.2% respectively in fractionated drip irrigations. When comparing the difference of one-time drip irrigation and fractionated drip irrigations treatments, we found that the pod filling weight, 100-pod weight and 100-kernel weight were higher. This result demonstrated that the fractionated drip irrigations were good for the mature of pods and nucleuses.Under the drip irrigations based on measurement of soil moisture content treatment,different drip irrigation quantities had great influence on yield, harvest index, and utilization efficiency of drip irrigation water. Because the yield of 5mm treatment was lowest and its biological yield didn’t appear to be much different from other treatments, so its harvest index was smallest. The harvest index and yield of 10 mm treatment were largest. The utilization efficiency of irrigation water was also very large and drip irrigation quantities were relatively smaller. Comprehensive, in the 10 mm treatment the effects of drip irrigation were best and the increase of yields was largest.4 The best drip irrigation mode and drip irrigation quantity during pod filling stage of peanutThe three drip irrigation modes have their own advantages and disadvantages. In production, we should choose the appropriate drip irrigation scheme according to the real situations. When we choose the one-time drip irrigation, the best drip irrigation quantity is 40 mm. when fractionated drip irrigation is used, the best drip irrigation quantity should be 20 mm and irrigation cycle should be 7 days. The optimal drip irrigation scheme is that drip irrigation begins when the relative soil moisture content of 0-20 cm soil layer is below 50%.And the drip irrigation quantity is 10 mm every time and irrigation cycle is 5 days. |
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