Effect of Sowing Date on the Growth Characteristics and Yield of Growth-Constrained Direct-Seeding Rice

Abstract

To investigate changes in the yield and physiological characteristics of indica hybrid rice varieties sown on different dates, we evaluated appropriate hybrid rice varieties and their optimal sowing dates in the hilly areas of Sichuan. Three popular indica rice varieties were used as experimental materials, and five sowing dates were set uniformly locally [16 May (SD1), 23 May (SD2), 30 May (SD3), 6 June (SD4), and 13 June (SD5)] to investigate differences in the yield characteristics, growth period, and dry matter accumulation. The results showed that, over the two years, the sowing-to-heading period and overall growth period of the three varieties shortened as the sowing date was delayed, and the difference in yield between the SD1 and SD2 treatments was not significant, owing to higher material accumulation after flowering and higher assimilative material transport capacity. These varieties are both photosensitive and tolerant to low temperatures. Among the three varieties tested, the Huangyouyuehesimiao (V3) cultivar had the highest yield, with 10.75 t ha−1 under the SD2 treatment. The impact of shifting the sowing date on yield components varied. Delaying the sowing date increased and then decreased the number of effective panicles, and the number of grains per panicle and the seed setting rate decreased by differing degrees. In summary, a high yield of indica hybrid rice can be maintained by sowing between 16 and 23 May each year in the study area. It indicated that indica hybrid rice in the hilly rice-producing region of Sichuan is highly adaptable to different sowing dates.

Influence of Sowing Time and Weed Management Practices on the Performance and Weed Dynamics of Direct Drum Seeded Rice

“…Hand weeding proved to be a more effective weed control method because it produced rice with greater WCE and lower weed density and nutrient depletion than other weed control methods. 47,48 Various weed management strategies have a significant impact on a crop's grain, straw, biological yield, and harvest index. Conoweeding (equivalent to weed free) though at par with sequential application of BSM + pretilachlor PE f b 2,4-D PoE recording increased yield was the result of enhancement in all yield parameters as well as a decrease in crop-weed competition.…”

“…The rice crop was able to synthesize more chlorophyll due to effective weed control, which improved the accumulation of photosynthates and increased translocation, which increased the number of grains, panicles, and test weight, and ultimately increased rice grain yield. Hand weeding proved to be a more effective weed control method because it produced rice with greater WCE and lower weed density and nutrient depletion than other weed control methods. , …”