| The experiment was conducted during 2013-2014 growing season at the Agronomy Experimental Station(36°09′ N, 117°09′ E) of Shandong Agricultural University in Tai’an, Shandong Province, China. The plots were 3×3 m2 in size. The winter wheat(Triticum aestivum L.) variety used for the experiment was Jimai 22. The experiment was split-plot design with three planting patterns and three irrigation amounts, and to study the effects of planting pattern and irrigation amount on farmland microclimate, soil water, leaf water, water use efficiency and yield under the same plant population densities of 200 × 104 ha-1. The experiment was used to determine the response characteristics of the crop water signals to different planting patterns and irrigation amounts and through the analysis of the relationship between water signals and soil water characteristics as well as crop growth, which provide theoretical foundation for agriculture water use and yield. Three planting patterns were single-single row(SS), single-double(SD) and double-double(DD), and three irrigation amounts of 0, 30, 60 mm were applied in each planting pattern at growth stages 34(GS34, stem elongation stage), GS48(booting stage), and GS70(milk development stage), respectively(Zadoks et al., 1974). The results showed that planting pattern and irrigation amount had significant effects on farmland microclimate, soil water, leaf water, water use efficiency and yield. The results were showed in the following:1 Farmland microclimate of winter wheatPlanting pattern and irrigation amount affected air temperature and relative humidity significantly(P < 0.05). DD planting pattern decreased the air temperature, which was good for reducing soil evaporate. The daily change of air temperature showed "Λ" type with the highest air temperature at 12:00 or 14:00. Air temperature was decreased with increasing irrigation mounts. Because of plant cover, air temperature at 5 cm was higher than that of 50 cm.Relative humidity was significantly and negatively correlated with air temperature(P < 0.05), but soil temperature was positively correlated with air temperature, therefore, relative humidity was decreased and soil temperature was increased with the increase of air temperature, and soil temperature showed some lag effects. With the increasing of soil depthand irrigation amount, soil temperature was decreased, and relative humidity and photosynthesis active radiation(PAR) capture ratio were increased. Soil temperature of SD planting pattern decreased at 0 and 10 cm soil depth, and DD planting pattern decreased at 5, 15 cm soil depth, however, planting pattern had no significant effect on soil temperature(P > 0.05). DD planting pattern had increased relative humidity ahd PAR capture ratio, and then improved farmland microclimate.2 The effects of planting pattern and irrigation amount on soil water signalsPlanting pattern, irrigation amount and the interaction between them significantly affected soil water(P < 0.05), in which irrigation amount rather than planting pattern had more significant effect on it; DD planting pattern increased soil water content of 0 mm condition. A positive correlation was observed among the soil water content, soil water storage and soil water potential, which showed that soil water storage and soil water potential increased(P < 0.05). Irrigation amount increased soil water content, soil water storage and soil water potential significantly(P < 0.05). Planting pattern and irrigation amount mainly increased 0-60 cm soil water content significantly(P < 0.05).The daily soil evaporation and evapotranspiration at different growth stage or total were changed with the changes of soil water content and farmland microclimate. The daily soil evaporation at filling stage(GS71) was lower than that of heading stage(GS49), which was decreased day by day through growth stage. The daily soil evaporation, soil evapotranspiration at different growth stage or total were increased significantly with the increasing irrigation amount(P < 0.05), and DD planting pattern were the lowest. There was a significant and positive line equation of yield and evapotranspiration(P < 0.01).3 The effects of planting pattern and irrigation amount on leaf water signalsLeaf stomatal conductance(SC), relative water content(RWC), water potential(Ψw) and osmotic potential(π) were significantly and negatively correlated with soil water, and a negative and significant correlation was observed among abscisic acid(ABA) and soil water(P < 0.05), so with the increasing irrigation amount, ABA was decreased and SC, RWC, Ψw, π were increased to weaken water stress. Planting pattern, irrigation amount and interaction effected on the indicators of leaf water signal under irrigation condition, in which irrigation amount rather than planting pattern had more significant effect on it. DD planting pattern increased SC, RWC, Ψw, π, but decreased ABA; leaf SC, RWC, Ψw, π were increased and ABA was increased with the increasing irrigation amount. The daily change of leaf Ψw was negatively and significantly correlated with air temperature. Ψw at GS49 was higher than that of GS71.Yield was positively correlated with SC, RWC, Ψw, π, and negatively and significantly correlated with ABA(P < 0.05), therefore, with the increasing of SC, RWC, Ψw, π, decreasing of ABA, yield was increased. Leaf water use efficiency(LWUE) and yield water use efficiency(WUE) was positively correlated with SC, Ψw, π, but the correlation was not significant(P > 0.05), so SC, Ψw, π decreased the WUE.4 Yield and water use efficiencyCrop growth gradually transferred to the reproductive growth at later growing season, and the ratio for dry weight of spike increased but the ratio for dry weight of leaf and stem decreased, so the dry weight water use efficiency(DMWUE) of leaf and stem was decreased as well DMWUE of spike was increased which was best to grain maturity. Planting pattern, irrigation amount and interaction had significant effects on yield and WUE(P < 0.05). DD planting pattern increased LWUE, DMWUE, WUE and yield, and irrigation decreased LWUE, DMWUE, WUE but increased yield. The interaction between DD planting pattern and irrigation amount could reduce the decrease of LWUE, DMWUE, WUE to a large increase of yield.Planting pattern, irrigation amount and the interaction between them had also significant effects on dry matter, harvest index and the related parameters of yield components(P < 0.05). DD planting pattern decreased dry matter, plant height, sterile spikelet number, and increased spike length, spikelet number, spikes m-2, grains spike-1 and thousand grain weight, and thus increased yield and harvest index. Spike height, spike length, spikelet number, spikes m-2, grains spike-1 and thousand grain weight was increased and sterile spikelet number was decreased with the increasing irrigation amount, so yield and harvest index were increased. Yield was significantly and positively correlated with spike height, spike length, spikelet number, spikes m-2(P < 0.05). A significant and positive line equation of yield and evapotranspiration was found(P < 0.01). |
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