Title: Agro-economic comparison of some rice cultivars and Lines in direct and transplanting cultivation methods
Author: Farzin Pouramir
Abstract: Transplanting is the common method of rice cultivation in Iran, which requires labor and a lot of money. In order to compare the agronomical and economical aspects of direct seeding and transplanting cultivation of some rice cultivars, an experiment was conducted during 2018 and 2019 in the research farm of Rice Research Institute of Iran-Rasht. The experiment was a split block based on a randomized complete block design with three replications. The main plots included the cultivation methods (transplanting and wet-direct seeding) and the sub-plots included rice cultivars (Hashemi, Anam, Gilaneh, Shiroodi, and Taher promising line). The results showed that paddy yield was not affected by the cultivation method in any of the two years studied, while the effect of cultivar in both years and the interaction of cultivation method × cultivar in the first year were effective on it. The paddy yield in 2018 was 5437 and 5585 kg for direct seeding and transplantation, respectively, and 5494 and 5269 kg for 2019, respectively. In 2018, Shiroodi and Hashemi in direct seeding cultivation with 7531 and 4451 kg, had the highest and lowest yield of paddy, respectively, while the yield of these cultivars in transplanting cultivation was recorded at 7214 and 4152 kg, respectively. In 2019, in both cultivation methods, Shiroodi had the highest paddy yield and no significant difference was observed between other cultivars in this regard. The effect of cultivation method (in the first year), cultivar, and the interaction effect of cultivation method and cultivar on the number of panicles per unit area were significant. In both years (except Anam cultivar in 2020), the number of cultivars panicle in direct seeding was more than transplanting. In 2019, Anam cultivar had the highest (444 panicles) number of panicles in the transplanting method, while the number of panicles of this cultivar in direct seeding was 517. In this year, the highest panicle number (626 panicles) in the direct seeding method belonged to Shiroodi cultivar, while this cultivar had 332 panicles/m2. In 2020, Hashemi and Taher promising line had the highest number of panicles per unit area (456 and 397 panicles per square meter, respectively), while the number of panicles of these two cultivars in direct seeding was 606 and 536 panicles per square meter, respectively. The effect of the cultivation method on the number of filled grains per panicle was not significant. However, in both experimental years, the number of filled grains in the transplanting method was 26% and 22% higher than the direct seeding method, respectively. This was while the effect of cultivar and the interaction effect of cultivation method and cultivar on the number of filled grains per panicle were significant. The growth period of cultivars in direct seeding cultivation in 2018 and 2019 was 14 and 15 days longer than transplanting cultivation, respectively. The greatest difference in terms of growth period between the two planting methods was observed in the vegetative growth stage and this difference was not significant in the reproductive growth stages. Calculating the required growth degree day (GDD) showed that the studied cultivars, according to the year of study, need higher GDD (1495 to 1658 GDD) to complete their growth cycle in direct seeding method than transplanting method (1308 to 1451 GDD). The total net costs paid in order to complete the cultivation, maintenance, and harvesting of one hectare of quality and high yielding cultivars by transplanting method in 1397, 184 to 193 million rials and for direct seeding were recorded 155 to 163 million rials, respectively. This was while in 1398, these values were 231 to 237 and 210 to 215 million rials for direct seeding and transplanting, respectively. Calculation of costs required for rice cultivation in two planting methods showed that direct seeding cultivation compared to transplanting cultivation leads to a 9 to 16 percent reduction in costs. In fact, most of these cost reductions were related to the elimination of rice nurseries and seedling preparation operations, as well as manual weeding operations in the direct seeding method. The result showed that the milled rice in direct seeding cultivation was higher than transplanting, but its percentage of head milled rice was lower. There was a big difference between the cultivars in this regard and Shiroodi cultivar had the best amount of milled rice and head milled rice, but Anam and Taher promising line had the lowest amount in this regard. The results of this study showed that rice direct seeding cultivation, in addition to not reducing rice yield, but also through maintaining the quality of rice production and also reducing production costs can be a suitable method for rice cultivation by rice farmers in the Northern provinces of Iran.
Keywords: paddy, production cost, growth period, yield