Effects of sowing date on the yield of different late rice variety types and its relationship with the allocation of temperature and light resources during the whole growth period of rice in the lower reaches of the Yangtze River. (English)

The yield, physiological characteristics, temperature, and light configurations of different late season rice varieties under different sowing treatments were studied to explore the suitable variety types of late japonica rice and their suitable sowing periods in the lower reaches of the Yangtze River. Two indica rice (CK), seven inbred japonica rice and three indica-japonica hybrid rice were used, and the sowing date adjustment experiment was carried out in the local suitable sowing period. The sowing treatments were set evenly within the locally available sowing period (mid-June to early July), with sowing periods set at 0 days (I), +T days (II), +2T days (III), +3T days (IV), and +4T days (V), respectively. The result showed that the total growing period of indica rice was slightly extended with delayed sowing, mainly due to the extension of the grain filling period. The grain filling period of japonica rice was also extended, but the total growing period was slightly shortened due to the greater shortening of the vegetative growth period. The yield of hybrid indica-japonica rice and inbred japonica rice fluctuated slightly with delayed sowing. The yield of inbred japonica rice [8.0±0.5 (t hm^-2)] was basically stable under five sowing dates. The yield of hybrid indica-japonica rice increased with delayed sowing dates, and peaked at sowing stage IV and sowing stage III in 2019 and 2020, respectively, with the highest yields of 11.0 t hm^-2 and 9.1 t hm^-2. The yield of indica rice varieties decreased significantly with the delay of sowing period. At the same time, yield differences among different variety types gradually increased with sowing delay, with yield differences increasing from 0.5 t hm^-2 to 5.1 t hm^-2. The effects of sowing changes on yield components varied. The number of effective panicles increased with sowing delay, the number of grains per panicle, and the grain filling rate decreased to different degrees, while the 1000-grain weight did not change significantly. The principal component analysis at different sowing dates revealed that with sowing delay the differences in variety characteristics evolved from differences in sink-source synergism to differences in sink-source synergism superimposed on temperature and light resource allocation, and then to differences in low temperature tolerance at later stages. As a result, indica rice should be sown appropriately early to make full use of the early temperature and light resources to achieve high yield by producing adequate panicles. Japonica rice possessed strong sowing adaptability, and indica-japonica hybrid rice had advantages in yield under all sowing periods. In the case of late harvest of the previous crop, the selection of indica-japonica hybrid rice varieties was more yield guarantee, while the selection of the best sowing period could maximize the yield of indica-japonica hybrids. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)