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

Expanding oilseed 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 oilseed rape 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-season rice maturity collocation against the background of climate change and focused on the combination of rice planting structure and double-season rice maturity collocation from 2011 to 2022 by considering the number of days required for agricultural activities, such as oilseed rape harvesting and rice transplanting, in actual rice-oilseed rape rotation mode using meteorological data from 85 meteorological stations in Jiangxi Province from 1961 to 2022. Under conditions of ensuring the normal growth of oilseed rape, the results showed that: 1) The harvest date of oilseed rape (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 from 2011 to 2022 than that in the 1960s under the background of climate warming. After 2011, oilseed rape were harvested in early April in southern Jiangxi, in early May in Jiujiang, and in middle and late April in other regions of the study area. The date of rice transplanting was middle April in most of the southern Jiangxi, and it was from late April to early May in northern and central Jiangxi. 2) The planting areas of single-season rice, ratooning rice, and double-season rice showed little change from 1961 to 1990; however, at the beginning of 1990s, the northern boundary of ratooning rice and double-season rice advanced to the north, and the planting area of single-season rice gradually shrank, whereas the planting area of ratooning and double-season rice gradually expanded under conditions of ensuring normal growth of oilseed rape. After 2011, double-season rice was grown in the south of Ji’an and southern Jiangxi, and ratooning rice was planted in the southern part of northern Jiangxi and most of central Jiangxi. Single-season rice was planted in the rest of Jiangxi. 3) Since 1991, the northern boundary of maturity collocation of double-season rice has moved northward. After 2011, the combination of early- and early-maturing varieties could be planted in the south of Ji’an and the southern edge of Fuzhou, the combination of early- and medium-maturing varieties could be planted in the north of southern Jiangxi, and the 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 oildseed rape, and also help meteorological departments to improve the meteorological service of the rice-oilseed rape rotation mode in Jiangxi Province.