This study aims to investigate the effects of key cultivation measures (sowing date, planting density, and nitrogen application rate) on grain yield, rice quality formation, and growth characteristics of the high-quality super rice variety Huazheyou 261. The results are expected to provide a theoretical basis for developing high-yield, high-quality, and high-efficiency cultivation techniques.

A single-factor field experiment was conducted using Huazheyou 261 as the test material. The treatments included four sowing dates (May 15, May 28, June 10, and June 23, denoted as S1, S2, S3, and S4), five transplanting densities (plant spacing of 27.0, 22.5, 19.3, 16.9, and 15.0 cm, denoted as D1 to D5, with a fixed row spacing of 30 cm), and five nitrogen application rates (0, 135, 180, 225, and 270 kg/hm², denoted as N0 to N4). Grain yield, rice quality, and growth characteristics were measured under different treatments. The correlations between yield and dry matter accumulation, as well as temperature and light resources, were analyzed. A comprehensive evaluation of rice quality under each treatment was also performed.

Sowing date, density and nitrogen application rate significantly affected grain yield, rice quality and growth characteristics of rice. Under each cultivation measure, the grain yield and comprehensive evaluation grade of rice quality showed an initial increase followed by a decrease. The grain yield of S3, D3 and N3 treatments was the highest, and the rice quality of S3, D3 and N2 treatments was the best. There was a significant quadratic relationship between grain yield and sowing date, density and nitrogen application rate. The trend of yield components and rice quality indexes varied with different cultivation measures. With the delay of sowing date, the decrease of density and the increase of nitrogen application rate, the growth period was delayed and the whole growth period was prolonged. The number of tillers increased, but the productive tiller percentage (except density treatment) decreased, and the SPAD value of leaves increased. The effective leaf area index, grain-leaf ratio (except under nitrogen treatments), dry matter accumulation from heading to maturity, harvest index, and temperature-light production efficiency all exhibited a trend of initial increase followed by decrease. Statistical analysis indicated that grain yield was significantly positively correlated with total spikelets and dry matter accumulation, with total spikelets contributing the most to grain yield. Principal component analysis identified milled rice rate, head milled rice rate, chalky grain rate, chalkiness, alkali spreading value, and gel consistency as key indicators for evaluating rice quality.

Under the experimental conditions, synergistic optimization of grain yield and rice quality for Huazheyou 261 in southeastern Zhejiang Province was achieved with the following practices: sowing between May 28 and June 15, transplanting at a row spacing of 30 cm and a plant spacing of 19.3-23.3 cm, and applying nitrogen at a rate of 176.6-209.8 kg/hm².