Effects Of Irrigation And Planting Patterns On Photosynthetic Characteristics Of Winter Wheat

An appropriate planting pattern in combination with timely irrigation applications may improve the photosynthetic efficiency and yield of winter wheat(Triticum aestivum L.). Field experiments using a split-plot design with three replicates were conducted at Taian, Shandong, China during2011-2012. Three planting patterns, double-row planting pattern (DRPP), single-double-row planting pattern (SDRPP) and single-row planting pattern (SRPP) and three irrigation levels-0,90and180mm-were assessed resulting in the same plant density (2×106plants ha-1). The canopy structure and the photosynthetic characteristics of flag leaves were investigated. The objective of this study was to develop a water-conserving planting pattern for winter wheat grown in the North China Plain.1. Effects of planting patterns on population develop dynamicsThe stem number of winter wheat in DRPP was significantly higher than that of the other planting patterns, which contributed to higher spike number per square meter. With the increases of irrigation, the stem number of winter wheat increased, which indicated that irrigation was benefit to the stem number. Analysis revealed a higher LAI in DRPP, at the same time, from filling to maturity stage the LAI in DRPP decreased slighter than that of the other planting patterns.2. Effects of planting patterns on PAR capture ratioThe available radiation (PAR) capture ratios in DRPP were higher than those in SRPP, which mainly because of the increase of PAR capture ratios at0-40cm above the ground. On other hand, the PAR capture ratios at12:00in DRPP were significantly higher than those in SRPP. Under0mm irrigation the advantage of DRPP in PAR capture ratio was more significant。3. Effects of planting patterns on leaf physiological characteristicsThe photosynthetic characteristics of flag leaves under irrigation were not significantly influenced by planting pattern. However, at maturity stage under0mm irrigation, the mean photosynthetic rate in flag leaves in DRPP was higher than that in the other planting patterns. Furthermore, winter wheat in DRPP under0mm irrigation was more conducive to increasing the apparent quantum yield (AQY) of flag leaves than that under irrigation. H2O conductance and transpiration rate of plants in DRPP were higher than those grown in the other planting patterns under the same irrigation conditions. The WUE of flag leaves in DSRPP was lower than that in DRPP because of lower transpiration rate. 4. Effects of planting patterns on dry matter accumulation and yieldThe dry matter accumulation of winter wheat in DRPP were significantly higher than that in the other planting patterns, however the ratios of dry matter accumulation of spike in DRPP were lower than those in DSRPP. The spike number per square meter in DRPP was higher than that in SRPP under the same irrigation conditions. The1000-kernel weight of the non-irrigated plants grown in DRPP was higher than that in the single-row planting pattern. Hence, the double-row planting pattern improved the photosynthetic capacity of winter wheat under water stress (non-irrigated plants). Under180mm irrigation, the yield of winter wheat in DSRPP was highest, which suggested that winter wheat in DRPP had bigger potential to increase the yield by increase the irrigation.The observations suggest that DRPP optimizes the canopy PAR distribution in winter wheat and contributes to the maintenance of higher photosynthetic capacity in flag leaves under water stress (rainfed conditions). This aspect can be exploited in demonstration trials to encourage winter wheat farmers in drought-prone areas to incorporate the use of DRPP.