Grain yield and leaf photosynthesis in transplanted winter wheat

Transplanting culture of wheat crop has received more and more attention in its yield-increasing potential and has been adopted in production in many areas of China. The agronomical and physiological mechanisms for transplanting culture to increase grain yield have not been understood enough. Therefore, the responses of plant growth, grain yield, leaf photosynthesis and some plant morphology to seedling transplanting culture (ST) were examined in comparison with early (ES) and late seed-sown (LS) wheat crops in both pot and field experiments. The seedlings were prepared with the root cut short and wilting before transplanted. ST yielded 23% (pot) and 21% (field) higher over ES and 128% (pot) and 41% (field) higher over LS, respectively. The increased grain yield was mainly attributed to increases in both grain number per spike and kernel weight. In pot experiment, the most significant difference in the spike characteristics of ST wheat plants compared with other plots was the increased spike length, which was mainly owing to the promoted elongation of rachis, i.e. the internodes between spikelets. Leaf area was larger in transplanted than in seed-sown plots, which contributed more than photosynthetic rate to the plant growth and grain yield. Transplanting increased resistance of wheat crops to lodging and both leaf rust and powdery mildew. It was concluded that the increased yield by transplanting culture was attributed to the more developed spike, larger leaf area, longer duration of green leaves, and higher resistance to lodging and disease in grain filling period.