Response of growth and grain yield of rice to seeding date and planting method in direct seeding in Rasht

Changing rice cultivation system from puddled-transplanted rice production to direct seeded rice greatly reduces labor and crop production cost. A field experiment was conducted at Rice Research Institute of Iran-Rasht in 2018 as split plot based on a randomized complete block design to evaluate the effect of seeding date and planting method on growth and grain yield, cv. Hashemi, in direct seeded rice. Main plots included seeding date (1, 8, 15, 22, 29 May, 5 and 12 June) and sub plots were planting method (broadcast seeding, row seeding and hill seeding). Moreover, transplanting plots were included to the experiment as control treatment. Analysis of variance showed that seeding date had significant effect on paddy yield, but planting method and the interaction effect between them had no significant effect on paddy yield. Maximum paddy yield were recorded at the dates of 1 and 15 May (4414 and 4325 kg ha-1, respectively). Paddy yield was significantly reduced when seeding date delayed, as grain yield reduce by 41, 43, and 70% at the seeding dates of 22, 29 May, and 5 June compared to the seeding date of 1 May. There was no significant difference in paddy yield between direct-seeded (4295±215 kg ha-1) and transplanting (4414±184 kg ha-1) production systems. Moreover, seeding date and planting method had no significant effect on weed biomass. In general, results revealed that optimum paddy yield in direct seeding was recorded at the seeding date of 1–15 May.