| This research was to explore the coupling effects of deficit irrigation at different growth stages and different nitrogen levels on the growth, physiological functions, yield, water-nitrogen use of eggplant and dynamics of soil NO3-N. Four irrigation modes were designed as W1 (DI in flowering and fruit setting stage), W2 (DI in the first fruit stage), W3 (DI in the full fruit stage) and Wo (Not exerting deficit irrigation) with three N application levels, N1 (0.1g/kgsoil), N2 (0.3g/kgsoil), N3 (0.5g/kgsoil).The conclusion was as follow:1. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, the plant height of treatments conducting deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage were negatively affected. With the increase of nitrogen fertilizer application, the plant height of all treatments was on the rise. Like plant height, stem diameter of treatments conducting deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage were negatively affected, but the effect of nitrogen application were not remarkable. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage had little effects on the number of leaves, so did different nitrogen levels. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, LAI of treatments conducting deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage were negatively affected and especially for treatments exerting water deficit at flowering and fruit stage, but the effect of nitrogen application to LAI were not remarkable.2. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, the root length and root volume of treatments conducting DI at the full fruit stage were significantly inhibited while those of treatments conducting DI at flowering and fruit stage and the first fruit stage were little affected. Compared to control treatments, the total length decreased 12.39%,18.82%,15.29%respectively and the total volume decreased 30.97%,42.36%,32.05%. With the increase of nitrogen fertilizer application, root length, root volume of all treatments rose steadily and reached the peak at middle nitrogen fertilizer application level and with the further increase of nitrogen application, datum of all treatments began to fell down. Root weight mainly distributed at 0-20cm soil layers and logarithmically reduced in the vertical direction of soil layers. With the increase of nitrogen fertilizer application, root inclined to distribute in shallow soil layers. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, the root activity of treatments conducting deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage were negatively affected and especially for treatments exerting DI at the full fruit stage, compared to control treatments, the root activity of DI at the full fruit stage decreased 32.72%,25.61%,35.71%respectively. The root activity were improved after re-watering and the compensatory effect of treatments exerting DI at flowering and fruit stage were more notable than that of treatments conducting DI at the first fruit stage. With the increase of nitrogen fertilizer application, root activity of all treatments appeared to decline when they were at the stages not conducting DI.3. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, the dry biomass both on the ground and under the ground of treatments conducting DI at the full fruit stage were significantly inhibited, but they were improved after re-watering and showed different level of compensatory effect. The effect of DI on the root system was less remarkable than that on the leaves, stem and fruit. The ratio of root/shoot declined with the developing of growth stages.4. Whenever at flowering and fruit stage or the first fruit stage or the full fruit stage, net photosynthetic rate of functional leaves of eggplant within daytime showed a bimodal curve and it reached the bottom at 12:00 am. With the development of growth stages, net photosynthetic rate presented an uptrend. The variation of transpiration rate between 8:00 am and 18:00 pm showed a single peak curve and with the development of growth stages, the transpiration rate presented a downtrend. The variation of stomatal conductance between 8:00 am and 18:00 pm showed a bimodal curve and with the development of growth stages, the stomatal conductance reached the peak at the first fruit stage and then began to fell down. Besides that, the effect of DI at any stages made the net photosynthetic rate, transpiration rate and stomatal conductance fall down. With the increase of nitrogen application, the net photosynthetic rate, transpiration rate and stomatal conductance rose steadily and reached the peak at middle nitrogen fertilizer application level and with the further increase of nitrogen application, datum of all treatments began to decrease.5. Compared with control treatments, under the same amount of nitrogen fertilizer application condition, the yield of treatments of DI at blossom and fruit-set stage, the first fruit stage,and full fruit stage decreased 6.13%,10.84%,14.64%; 3.94%,5.62%,11.6%,和11.35%,4.23%,16.14%respectively. The effect of deficit irrigation at blossom and fruit-set period, the first fruit period and full bearing period on WUE of eggplant were not significant. At low and middle nitrogen fertilizer application level, treatments of DI at blossom and fruit-set period obtain high WUE on the basis of high yield. Under low and middle nitrogen application levels, water sensitivity index of DI in the full bearing period was the largest, followed by treatments of DI in the first fruit period and DI in blossom and fruit-set period, while under high nitrogen application level, water sensitivity index of DI in the first fruit period rised remarkably. Through the analysis of water sensitivity index, the parameterλin Jensen model was affected little by the water consumption at each growth stages while there was significance betweenλand nitrogen levels and especially under high nitrogen level,λ, of blossom and fruit-set stage research the highest value,1.9981.6. Nitrogen accumulation of eggplant was significantly affected by water deficit at different growth stages and different nitrogen levels. Water deficit at the first fruit stage and the full fruit stage had a negative effect on nitrogen accumulation of eggplant, especially water deficit at the full fruit stage. Nitrogen accumulation of eggplant under low and high nitrogen conditions was also negatively affected by water deficit at the blossom and fruit-set stage, but compared with control treatment, nitrogen accumulation of eggplant under moderate nitrogen condition was higher than that of control treatment. With the increase of nitrogen application, nitrogen accumulation of eggplant of all treatments rose steadily and reached the peak at middle nitrogen fertilizer application level and with the further increase of nitrogen application, datum of all treatments began to fell down. The total amount of nitrogen accumulation of fruit was the highest and followed by leaves, root and stem. Within all treatments, nitrogen accumulation at different parts of eggplant was most inhibited by water deficit at the full fruit stage. In addition, FNUR and FNUE were most affected by water deficit at the full fruit stage. With the increase of nitrogen application, FNUR and FNUE of eggplant of all treatments decreased steadily. From an overall perspective, NPE of eggplant of treatments carried water deficit were higher than that of control treatments.7. With the development of growth stages, the content of NO3-N showed a downtrend; at each growth stages, the content of NO3-N within 0-10cm soil layer was the lowest while that within 20-30cm soil layer reached the peak. With the increase of nitrogen application, the content of NO3-N in 0-30cm soil layer at each growth stages increased remarkably. Under the same nitrogen level, NO3-N leaching of control treatments was earlier than treatments conducting DI within the growth stages because of relatively more amount of water applied.8. With the development of growth stages, the water consumption increased steadily. With regard to the water consumption per day, it also showed a uptrend from flowering and fruit stage to the full fruit stage, and the average water consumption per day were 1.91mm/d, 2.45 mm/d,3.38 mm/d respectively. The average water consumption per day of treatments conducting deficit irrigation either at flowering and fruit stage or the first fruit stage or the full fruit stage were remarkably decreased. With the increase of nitrogen application, the total water consumption and average water consumption per day showed a downtrend.
|
PDF Full Text Request