Pre-Treatment of Rice Seedlings With 1–Methylcyclopropene (1-MCP) Increases Plant Stand and Tiller Number in Transplanted Rice.

Rice (Oryza sativa L.) seedling growth in the nursery and the transplanting shock experienced by seedlings affect the subsequent plant stand, growth and development of transplanted rice.  The study’s objective was to determine if application of 1–methylcyclopropene (1-MCP) to the seedlings prior to transplanting can prevent the transplanting shock. Plants were transplanted 21 days after emergence with root pruning (0%, 25% or 50%). Three days prior to transplanting, one set of plants was treated with 1-MCP (25 g a.i ha^-1) and the other set was treated with Latron (adjuvant 0.25%; control). Plant height, numbers of tillers and leaves, and chlorophyll concentration (SPAD index) were determined weekly. Leaf photosynthetic rate was measured 5 days after transplanting. Root dry weight, shoot dry weight and root length were determined at harvest (4 weeks after transplanting). Our results indicated that root pruning did not have an effect on plant height, number of leaves, root dry weight, or root length. However, root pruning had negative effects on number of tillers, chlorophyll (SPAD), shoot dry weight and net photosynthetic rate. Plants treated with 1-MCP showed greater number of tillers, chlorophyll concentration, root dry weight, and net photosynthetic rate, compared to the plants of the control. Our results indicate that application of 1-MCP prior to transplanting can prevent the transplanting shock treatment effect in rice.