Modern wheat (Triticum aestivum L.) is one of the most ozone (O(3))-sensitive crops. However, little is known about its genetic background of O(3) sensitivity, which is fundamental for breeding O(3)-resistant cultivars. Wild and cultivated species of winter wheat including donors of the A, B and D genomes of T. aestivum were exposed to 100 ppb O(3) or charcoal-filtered air in open top chambers for 21 d. Responses to O(3) were assessed by visible O(3) injury, gas exchange, chlorophyll fluorescence, relative growth rate, and biomass accumulation. Ozone significantly decreased light-saturated net photosynthetic rate (-37%) and instantaneous transpiration efficiency (-42%), but increased stomatal conductance (+11%) and intercellular CO(2) concentration (+11%). Elevated O(3) depressed ground fluorescence (-8%), maximum fluorescence (-26%), variable fluorescence (-31%), and maximum photochemical efficiency (-7%). Ozone also decreased relative growth rate and the allometric coefficient, which finally reduced total biomass accumulation (-54%), but to a greater extent in roots (-77%) than in the shoot (-44%). Winter wheat exhibited significant interspecies variation in the impacts of elevated O(3) on photosynthesis and growth. Primitive cultivated wheat demonstrated the highest relative O(3) tolerance followed by modern wheat and wild wheat showed the lowest. Among the genome donors of modern wheat, Aegilops tauschii (DD) behaved as the most O(3)-sensitive followed by T. monococcum (AA) and Triticum turgidum ssp. durum (AABB) appeared to be the most O(3)-tolerant. It was concluded that the higher O(3) sensitivity of modern wheat was attributed to the increased O(3) sensitivity of Aegilops tauschii (DD), but not to Triticum turgidum ssp. durum (AABB) during speciation.

SUMMARYThe effects of planting pattern and irrigation on the soil water content, stomatal conductance, leaf relative water content, leaf water potential and leaf water use efficiency of winter wheat were investigated in North China during the 2008/09 and 2009/10 growing seasons. A field experiment was conducted using a randomized complete block design that consisted of three planting patterns: (i) a uniform row spacing of 25 cm, and alternating wide–narrow row spacing of 40 and 20 cm tested as (ii) flat and (iii) furrow–ridge seedbeds. In addition, irrigation treatments of 90, 135 and 180 mm were used. The planting pattern, irrigation treatments and interactions between them significantly affected soil water content, stomatal conductance, leaf relative water content, leaf water potential and leaf water use efficiency. The soil water content, stomatal conductance, leaf relative water content, leaf water potential, grains/spike, thousand grain weight, leaf water use efficiency and yield were highest in the furrow–ridge seedbed planting pattern and increased with increasing irrigation (except for the leaf water use efficiency). The leaf water use efficiency in the 135 mm irrigation treatment was significantly greater than in the other treatments. In addition, soil water content, stomatal conductance, leaf relative water content, leaf water potential, grains/spike and thousand grain weight were positively correlated with leaf water use efficiency and yield of winter wheat. The interaction between the furrow–ridge seedbed planting pattern and 135 mm irrigation increased soil water content, leaf water indices, grains/spike, thousand grain weight, leaf water use efficiency and yield. These results indicated that a beneficial response occurred for wheat yield. The furrow–ridge seedbed planting pattern combined with 135 mm of irrigation improved the soil and leaf water status and could increase wheat yield while using less water.

Winter wheat (Triticum aestivum L.) is characterized by a high tillering capacity and disadvantageous spatial structures, which may result in intraspecific competition. This study aimed to determine whether tiller productivity, radiation use efficiency (RUE), and grain yield of winter wheat could be manipulated through irrigation and precision planting patterns in North China. The experiment was conducted during winter seasons of 2011/2012, 2012/2013, and 2013/2014 at Tai'an, Shandong Province, China. The field experiment was based on a two‐factor split‐plot design with three replications under the same plant density (200 × 104 ha−1). Three irrigation levels (0, 90, and 180 mm) were allocated to main plots, and three planting patterns namely single–single (SS), single–double (SD), and double–double (DD) were kept in subplots. Irrigation amount 0, 30, 60 mm of water were applied at GS34, GS48, and GS70, respectively. Results showed that photosynthetically active radiation (PAR) capture ratio of 0 mm was higher than that of the 90‐mm irrigation at 0 to 40 cm, but irrigation increased the total PAR capture ratio, leaf area index (LAI), RUE, and grain yield. The interaction of irrigation × planting pattern indicated that the grain yield of SD was high under 180‐mm irrigation and that of DD was high under 0‐ and 90‐mm irrigations. Leaf area index, PAR capture ratio, and RUE of DD were higher than those of SD under 90‐mm irrigation. The application of DD planting pattern combined with 90‐mm irrigation resulted in positive response to yield.Core Ideas Double‐double row improved distribution of radiation, leaf area index, and stem number. Precision planting patterns increased radiation use efficiency and yield of wheat. The optimal precision planting pattern under abundant and scarce water in China.

SUMMARYProductivity and water resource usage efficiency are crucial issues in sustainable agriculture. The aims of the present research were to compare and evaluate the soil moisture content (SMC), evapotranspiration (ETa), yield, water-use efficiency (WUE), and net return of winter wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] under different plant population distribution patterns and to identify the possible ways to improve water utilization. Using the same plant population for a given crop, the experiments consisted of four spacings between rows (row spacings) for winter wheat (cvar Shannong 919) under both rainfed and irrigated conditions and five row spacings for summer soybean (cvar Ludou 4) under rainfed conditions. For winter wheat, the stem number with row spacing of 49 cm was the lowest in all treatments. The SMC was enhanced by irrigation, particularly at the 10-40 cm depth. The yield and WUE were negatively correlated with row spacing and were greater with narrower row spacing than with wider rows. For soybean, SMC in uniform distribution (spacing between plants) treatments was greater at lower depths than at shallower depths for each row spacing treatment. A high yield, WUE and net return of winter wheat and soybean can be achieved with narrower row spacing. Combining winter wheat row spacing of 14 cm with soybean row spacing of 18 cm and soybean row spacing of 27 cm is a highly suitable planting system for the plains of Northern China.