The effect of planting date and pattern on vegetative characteristics and yield cotton in Darab region

Background and objective: In recent years, researchers have considered increasing the water productivity of crops, including cotton, by changing the timing and planting density. On the other hand, studies have shown that transplanting cotton compared to no-till has a significant effect on reducing water use and thus increasing water use efficiency in Iran. Therefore, this study was conducted to evaluate the effects of planting date and method (no-till or transplanting) on quantitative and qualitative yield of cotton in Fars province.
Material and Methods: This factorial trial was conducted in a randomized block experiment with three replications in 2020 at a research farm in Darab city, Fars province. The experimental factors included cropping systems at three levels of planting 35 and 45 days old transplants and no-till cotton as main factors and date of planting and no-till at three levels of May 4 and 19 and June 4 as sub-factors. In this study, seedling establishment percentage, plant height, leaf area index, number of bolls per plant, boll weight, lint yield and early maturity percentage and finally water use efficiency were evaluated. At the end of the experiment, the data were analyzed using SAS software version 9.4 and the means were compared using Duncan's test at 5% probability level.
Results: The results of this study showed that most of the evaluated indices of cotton were higher in 45-day planting than 35-day planting and no-till. Thus, the highest establishment percentage (87.18%), leaf area index (2.24), plant height (96.78 cm), number of bolls (27.61) and single boll weight (4.56 g), lint yield (2862.4 kg/ha) and early maturity percentage (68.3) were obtained in 45-day transplants. In general, transplanting increased the average leaf area index, plant height, percentage of establishment and number and weight of bolls compared to direct planting. In most cases, the highest number of traits measured was on May 19. The highest establishment percentage (81.14%), leaf area index (2.16), plant height (97.44 cm), number of bolls per plant and weight of individual boll and yield (2694.6 kg/ha) were measured at this planting date. The results of this study showed that transplanting significantly increased water use efficiency compared to no-till. The highest water use efficiency (0.66 kg/m³) was obtained in 45-day-old transplanting, which was significantly different from other planting systems. Overall, transplanting improved the water use efficiency of cotton by about 25% compared to no-till (0.50 kg/m³).
Conclusion: transplanting increases the quantity and quality of cotton compared to no-till, as seedlings are not exposed to adverse environmental conditions such as frost at the beginning of the season and flowering time is prolonged. In irrigated farming, transplanting is one of the most acceptable methods to achieve high yield. The results of this study show that transplanting cotton seedlings on May 19 leads to a significant increase in the quantitative and qualitative characteristics of cotton. On the other hand, the highest water use efficiency of cotton was obtained under these conditions, so transplanting cotton seedlings at the end of May is recommended in Darab region of Fars province.