The impact of planting date on biomass and grain yield of proso millet in Rasht

Cultivating forage plants is an important way to address the problem of a lack of forage and its consequences, which can be beneficial to the economy and improving food security. Millet is an excellent source of forage for livestock because of its high dry matter production, low water footprint and adaptability to different environments. However, there is not available well documented experimental results on the crop planting date for Rasht, Guilan province, Iran. Therefore, this study was performed to evaluate the impact of various planting dates on the crop grain and biomass yield in Rasht, which could be extended to similar regions.

To investigate the impact of various planting dates on the grain and biomass yield of proso millet (cv. Pishahang) in the climatic conditions of Rasht city, an experiment was conducted in a randomized complete block design with four replications in the research field of the Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran, in two cropping years, 2016-17 and 2017-18. The experimental treatments in both years were four planting dates, May 29, June 27, July 29, and August 29 in the first year, and June 4, July 7, August 5, and September 6 in the second year. The central rows of each plot were used to measure grain yield and biomass respecting the margin effect, and recorded in terms of kg.ha-1. We tracked the growth of the leaf area over time by measuring leaf area and maximum leaf area index from tillering stage to final harvest. The SAS software was used to analyze variance and compare data values.

The results of the study showed that the interaction between planting date and year had a significant effect on biomass yield, grain yield, harvest index, leaf area index, panicle weight, panicle number, grain number, and a 1000- grain weight. In the first year, planting millet on May 29 resulted in the highest biomass (9927 kg.ha-1), grain yield (2182 kg.ha-1), panicle dry weight (25.53 g.plant-1), panicle number (15.08 per plant), grain number (2121 per plant), 1000-grain weight (5.23 g), and leaf area index (4.9). This was likely due to the favorable temperature conditions at that time of year. In the second year, planting millet on July 7 resulted in the highest biomass yield (6537 kg.ha-1), grain yield (1283 kg.ha-1), panicle dry weight (11.77 g.plant-1), panicle number (6.75 per plant), grain number (1345 per plant), 1000-grain weight (4.7 g), and leaf area index (3.69). This was likely due to the favorable meteorological parameters at that time of year, such as maximum and minimum temperature (30.24 and 21.46 0C, respectively), solar radiation (17.7 MJ.m-2.day-1), and sunshine hours (7.67 hours).

Overall, the results of the study suggest that planting millet in the period from June 4 to June 27 will result in the highest dry matter and grain yield in the Rasht region.