Optimizing proso millet production according to planting date and growth analysis

The increasing demand for diverse fodder plants, along with the challenges of its production such as the pressure on pastures, has led to increased attention to strategies for maximizing the production of these plants per unit area. Millets are a good choice for crop rotation and production patterns in different regions due to their high diversity, high adaptability, high dry matter production, and high nutritional value. However, the appropriate planting date and the compatibility of the growth stages of millet with environmental conditions are essential for maximizing production. This study was conducted to evaluate the effect of different planting dates on the growth indicators of proso millet and how its growth stages are compatible with environmental conditions.

To achieve the objectives of the research, a two-year field experiment was conducted in 2016-2017 and 2017-2018 at the research farm of the Faculty of Agricultural Sciences of the University of Guilan. A randomized complete block design with four replications and four planting dates was used (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). Plant growth indices, plant response, and the compatibility of plant growth stages with environmental conditions were investigated through repeated sampling, measurement of plant leaf area and dry matter of different plant parts, and recording of phenological stages.

The results of this experiment showed that the interaction between year, planting date, and sampling time had a significant effect on the accumulation of dry matter and the growth indicators studied, such as leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net absorption rate (NAR), leaf area ratio (LAR), and leaf weight ratio (LWR). In the first cropping year, the highest total dry matter accumulation of proso millet, with an average of 1030.8 grams per square meter, was obtained by planting it on June 27. This was due to the maximum LAI (5.14 cm²·m²) and crop growth rate (35.5 g·m²·day⁻¹) obtained in the second planting time, which led to a significant increase in dry matter compared to the other three planting dates. However, in the second year of the experiment, planting proso millet on June 4 resulted in a significant increase in LAI (3.69 cm²·m²), CGR (25.99 g·m²·day⁻¹), and NAR (18.13 g per square meter of leaf area per day) compared to the other three planting dates. As a result of the aforementioned growth indicators, the total dry matter accumulation of proso millet was 734.66 grams per square meter, which showed a significant increase compared to the other three planting dates.

Overall, the results of this experiment suggest that the optimal planting date for proso millet in Rasht is between June 4 and June 27. Planting during this period resulted in the highest accumulation of dry matter and the most favorable growth indices. The findings of this study can be used to improve the cultivation practices of proso millet in Rasht and other similar regions.