Effects of Sowing Date and Sowing Rate on Growth and Yield of Spring Buckwheat

To screen out the optimal cultivation combination for the main spring buckwheat varieties in central Jiangsu region, a two-factor split-plot experiment was conducted in Taizhou, using Suqiao 2 and Pintian 2 as test materials. Three sowing dates (B₁: March 13th, B₂: March 20th, B₃: March 27th) and four sowing rates (C₁: 60 kg/hm², C₂: 75 kg/hm², C₃: 90 kg/hm², C₄: 105 kg/hm²) were set to study their effects on the growth period, agronomic traits, dry matter accumulation and yield of spring buckwheat. The results showed that: (1) Delayed sowing date significantly shortened the growth period, while sowing rate had no effect on the growth period. (2) The agronomic traits exhibited variety specificity. For Suqiao 2, low sowing rate optimized number of branches and number of nodes. For Pintian 2, medium sowing rate increased stem diameter, and low sowing rate increased the number of branches and nodes. (3) In terms of dry matter accumulation, low sowing rate increased the dry matter of Suqiao 2 at the flowering and maturity stages, while the dry matter of Pintian 2 at the flowering stage under medium and late sowing was higher than that under early sowing. (4) Yield was mainly regulated by sowing date. The yield under sowing date B₁ was the highest (Suqiao 2: 1193.93 kg/hm², Pintian 2: 1122.23 kg/hm²), and that under B₃ was the lowest (＜220 kg/hm²). The highyield combinations for both varieties were B₁C₃ and B₁C₄, but there was no significant difference in yield of Pintian 2 among B₁C₁ to B₁C₄. In conclusion, the optimal cultivation combinations for Suqiao 2 and Pintian 2 in central Jiangsu region are sowing on March 13th, with a sowing rate of 90~105 kg/hm² for Suqiao 2 and 60~105 kg/hm² for Pintian 2.