ABSTRACTto better understand the potential for improving biomass accumulation and radiation use efficiency (rUE) of winter wheat under deficit irrigation regimes, in 2006-2007 and 2007-2008, an experiment was conducted at the luancheng Experimental Station of Chinese academy of Science to study the effects of deficit irrigation regimes on the photosynthetic active radiation (Par), biomass accumulation, grain yield, and rUE of winter wheat. in this experiment, field experiment involving winter wheat with 1, 2 and 3 irrigation applications at sowing, jointing, or heading stages was conducted, and total irrigation water was all controlled at 120 mm. The results indicate that irrigation 2 or 3 times could help to increase the Par capture ratio in the later growing season of winter wheat; this result was mainly due to the changes in the vertical distributions of leaf area index (lai) and a significant increase of the lai at 0-20 cm above the ground surface (lSD, P < 0.05). Compared with irrigation only once during the growing season of winter wheat, irrigation 2 times significantly (lSD, P < 0.05) increased aboveground dry matter at maturity; irrigation at sowing and heading or jointing and heading stages significantly (lSD, P < 0.05) improved the grain yield, and irrigation at jointing and heading stages provided the highest rUE (0.56 g/mol). Combining the grain yield and rUE, it can be concluded that irrigation at jointing and heading stages has higher grain yield and rUE, which will offer a sound measurement for developing deficit irrigation regimes in north China.
The aim of this study is to exam the effect of microsprinkler irrigation technology under plastic film (MSPF) and to evaluate the reasonable micropore group spacing and capillary arrangement density in the greenhouse. Compared with drip irrigation under plastic film (DIPF) and microsprinkling irrigation (MSI) conditions, the effects of different micropore group spacing (L1: 30 cm micropore group spacing, L2: 50 cm micropore group spacing) and capillary arrangement density (C1: one pipe for one row, C2: one pipe for two rows, and C3: one pipe for three rows) with the MSPF on photosynthetic characteristics and fruit yield of tomatoes were studied using completely randomized trial design. The results showed that under the same irrigation amount, compared with DIPF and MSI, the photosynthetic rate of tomatoes treated with L1C2 increased by 8.24% and 13.55%, respectively. The total dry matter accumulation, yield, and water use efficiency at condition of L1C2 increased by 12.16%, 19.39%, and 10.03% compared with DIPF and 26.38%, 20.46%, and 31.02% compared with MSI, respectively. The results provide evidence that the MSPF can be applied to greenhouse tomatoes. The photosynthetic rate, total dry matter accumulation, yield, and water use efficiency of tomato leaves cultivated at a micropore group spacing of 30 cm were 1.07, 1.13, 1.14, and 1.13 times higher than those of 50 cm, respectively. With the decrease in capillary arrangement density, the photosynthetic characteristics of the tomato leaves, the total dry matter accumulation, and yield of tomatoes all experienced a decline. It is recommended to use a combination of one pipe for two rows of capillaries at a 30 cm micropore group spacing as the technical parameter of greenhouse tomato with MSPF in arid and semiarid sandy loam soils.
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