The change of rice planting structure in rice-oilseed rape rotation mode in Jiangxi Province under the background of climate change

Expanding rape production in winter fallow fields in Jiangxi has recently been promoted vigorously to satisfy the rapidly growing demand for edible vegetable oil in China; however, the phenomenon of rice and winter rapeseed competing for land has emerged in different areas in the actual development process. This study investigated the changing characteristics of rice planting structure and double-cropping rice maturity collocation against the background of climate change and focused on the combination of rice planting structure and double-cropping rice maturity collocation after 2011 by considering the number of days required for agricultural activities, such as rape harvesting and rice transplanting, in actual rice oil production using meteorological data from 85 meteorological stations in Jiangxi Province from 1961 to 2022. Under conditions of ensuring the normal growth of rapeseed, the results showed that: 1) The harvest date of rapeseed (rice transplanting) was different from north to south, which was early in the south and late in the north, and showed an advancing trend that was 13 days earlier than in the 1960s after 2011 under the background of climate warming. After 2011, rapeseed harvest dates were the first 10 days in April in southern Jiangxi, the first 10 days in May in Jiujiang, and the last 20 days in other regions. The date of rice transplanting was mid-April in most of the southern Jiangxi Province, the last ten days of April, and the first ten days of May in northern and central Jiangxi Provinces. 2) The planting areas of single-season rice, recycled rice, and double-season rice showed little change from 1961 to 1990; however, at the beginning of 1991, the northern boundary of single-season, recycled, and double-season rice advanced to the north, and the planting scope of single-season rice gradually shrank, whereas the planting scope of recycled and double-season rice gradually expanded under conditions of ensuring normal growth of rape. After 2011, double-season rice was grown in southern Ji’an and southern Gannan, where it was planted in the southern part of northern Jiangxi and most of central Jiangxi. Single-season rice was planted in the rest of the country. 3) Since 1991, the northern boundary of the mature combination of double-cropped rice has moved northward. After 2011, a combination of early- and early-maturing varieties could be planted in the south of Ji’an and the southern edge of Fuzhou, a combination of early- and medium-maturing varieties could be planted in the north of southern Jiangxi, and a combination of early- and late-maturing varieties or medium- and medium-maturing varieties could be planted in the central and southern parts of southern Jiangxi. The results can provide a reference for the balanced development of rice and rapeseed and also help meteorological departments improve the meteorological service of the rice-oilseed rape rotation mode in Jiangxi Province.