Changes of Safe Production Dates of Double-season Rice in the Middle Reaches of the Yangtze River

Abstract

Safe production date is an important basis for varieties and planting patterns selection, high use efficiency of heat and light resources, and production season safety. In this study, the daily average temperatures during the 50 years(1960–2009) provided by 47 meteorological stations in the Middle Reaches of the Yangtze River were analyzed, and several safe production dates for double-season rice with 50% and 80% guarantee rates were provided. At the 80% guarantee rate of the safe dates generally used in the double-season rice production, compared with the first 25-year period, the safe sowing dates of early-season rice seedlings with film-mulching in dry nursery in the second 25-year period were three-day delay, but those of the seedlings without film-mulching in watered nursery were three-day ahead of time; the safe transplanting dates of the seedlings shifted to three days early. The safe production dates for the early rice with film-mulching in dry nursery shortened four days, but ones for the early rice in the watered nursery was one more day. The safe full heading dates for the late-season hybrid indica rice were three days early, but those for the late-season indica rice were one day delay, and basically, its mature date as usual. The safe production dates with 80% guarantee rate during the second 25-year period were offered by meteorological stations, which can be referred in production arrangement, varieties and planting patterns for double-season rice in every regions to the nearest guiding principles. The changes of climate and safe production date were not more significant in the Middle Reaches of the Yangtze River than in the Northeast and the North China. The obvious advance of the safe production dates and safe planting dates for the early rice in the watered nursery facilitates early sowing, increasing yield potential except the rest of safe production dates. Therefore, sewers should reasonably arrange layout in these regions according to the safe production dates.