Effect of planting uniformity with machine on yield construction and quality formation of rice

Planting uniformity plays a crucial role in determining the yield and quality of rice. This experiment aimed to elucidate the mechanism behind the simultaneous improvement of uniformity, yield, and quality. Three varieties were used in the study: Yongyou 1540 (<italic>indica-japonica</italic> hybrid rice), Zhehexiang 2 (inbred <italic>japonica</italic> rice), and Huazheyou 210 (hybrid <italic>indica</italic> rice). Four treatments with varying planting uniformity were established: T₁ (drill sowing, planting uniformity of 65%-75%), T₂ (broadcast sowing, planting uniformity of 45%-55%), T₃ (manual simulated mechanical rice transplanting, planting uniformity of 100%), and T₄ (manual simulated mechanical rice transplanting, planting uniformity of 50%). The study compared and analyzed the dynamic changes in tiller number, leaf area photosynthetic efficiency, dry matter accumulation and transport, yield formation, and rice quality across different planting uniformity groups. The results showed as follows: (1) Enhanced planting uniformity increased the number of productive tillers by promoting tillering. The average number of tillers at the tillering peak stage was highest in T₃, followed by T₁, T₂, and T₄, with a consistent trend across different varieties. (2) Enhanced planting uniformity led to an increase in population leaf area index, particularly in the highly effective leaf area index of the top three leaves at the heading stage. Additionally, improved uniformity enhanced dry matter accumulation and facilitated its transportation. Dry matter accumulation at maturity followed the order T₃ &gt; T₁ &gt; T₂ &gt; T₄, with consistent trends observed among different varieties. However, there was no significant difference between T₂ and T₄. The effect of uniformity on stem sheath material movement during the filling stage varied among varieties, with no significant differences found between T₁, T₂, and T₄. (3) The number of grains per panicle did not significantly differ under different uniformity treatments. However, high planting uniformity resulted in a more uniform distribution of grains on primary and secondary branches. (4) Increased yield in high uniformity populations was primarily attributed to the effective panicle number, with consistent trends observed among different varieties. The average yield of T₃was 8.16%, 15.41%, and 15.61% higher than that of T₁, T₂, and T₄, respectively. (5) Improving planting uniformity increased the brown rice rate, milled rice rate, head rice rate, and protein content, while decreasing chalkiness and chalky rice rate. These findings indicate that improving planting uniformity can promote tillering, increase leaf area index and dry matter accumulation, enhance effective panicle number, and ultimately improve yield and milled rice rate, as well as rice quality to some extent. The experimental results highlight the potential of precision sowing machines to improve rice yield and quality by enhancing planting uniformity.