Abstract:

In order to explore the effect of sowing date on rice spikelets of main stem under different planting pattern (early−season rice, mid−season rice, ratoon rice and late−season rice planting pattern), an experiment with four sowing dates were conducted from 2018 to 2022 in Nanchang, Jiangxi province, in which the main varieties grown in Jiangxi were used. The results showed that the growth time required from sowing to heading stage for early−season rice and ratoon rice planting patterns showed a shortening trend with the sowing date were delayed, while the late−season rice planting pattern showed a longer trend with the sowing date were delayed. The sowing date had an extremely significantly (P<0.01) impact on the number of primary branches, secondary branches, and total spikelets on main stem under four planting patterns. Timely and early sowing of early-season rice and ratoon rice planting pattern were beneficial to increasing the number of primary branches, secondary branches, and total spikelets on main stem. Sowing early or late in middle−season rice and late−season rice planting pattern were not conducive to the increase of the number of primary branches, secondary branches, and total spikelets on main stem. There were an extremely significantly (P<0.01) correlation between the number of secondary branches and the total spikelets on main stems in four planting pattern. there were a significant correlation between the number of primary branches and the total spikelets on main stem in the middle−season rice, ratoon rice and late−season rice planting patterns (P<0.05), but the correlation with the total spikelets on main stem of early−season rice planting pattern was not significant. The correlation coefficient showed that the number of secondary branches > the number of primary branches. Path analysis showed that the contribution rate of the number of secondary branches to the total spikelets on main stem in each planting pattern were greater than the number of primary branches. In summary, the sowing date of four planting patterns in Jiangxi had a great impact on the number of primary branches, secondary branches, and total spikelets on main stem. It was necessary to reasonably arrange the sowing dates of four rice planting pattern. Among them, under the conditions of this experiment, the sowing dates of early−season rice and ratoon rice planting pattern were suitable to been advanced to March 11 and March 15 respectively, and the sowing dates of middle-season rice and late-season rice planting pattern were suitable to been arranged on May 15 and June 20−23 respectively, and it was beneficial to increase the number of primary and secondary branches, and then increased the total spikelets on main stem.

Key words: Planting pattern, Sowing date, Branches, Spikelets