Comparison of grain and forage yields of pearl millet and proso millet under irrigated and rainfed conditions across sowing dates

Background and objectives: Millets, a group of small-seeded cereals, exhibit remarkable performance in arid and semi-arid regions due to their high drought tolerance, low water requirements, and efficient water use. They are capable of producing substantial and stable forage yields under both irrigated and rainfed conditions. However, there is limited information on the management of millet cultivation under rainfed conditions in Mediterranean regions. This study aimed to compare the grain and forage yields of two millet species, pearl millet (Pennisetum glaucum (L.) R. Br.) and proso millet (Panicum miliaceum L.), under irrigated and rainfed conditions in Rasht.
Materials and methods: The experiment was conducted during the 2018-2019 growing season at the research farm of the Faculty of Agricultural Sciences, University of Guilan, using a split-plot factorial design within a randomized complete block design with four replications. The main plots consisted of two irrigation regimes (rainfed and irrigated), and the sub-plots comprised a combination of two millet species (pearl millet cv. Mehran and proso millet cv. Pishahang) and four sowing dates (June 4, July 7, August 5, and September 6).
Results: Analysis of variance revealed that the interaction between sowing date and irrigation regime, as well as the interaction between sowing date and species, significantly affected biomass yield, grain yield, panicle dry matter, number of filled grains, and thousand-grain weight. The number of panicles per plant was significantly influenced by the interaction between sowing date and species. The comparison of mean interaction effects of irrigation regime and sowing date indicated that in both irrigation regimes, delaying sowing from June 4 to September 6 led to a decrease in average grain and biomass yields. However, the results varied across different sowing dates. Specifically, on June 4, August 5, and September 6, the average grain and biomass yields under both irrigated and rainfed conditions were similar. In contrast, on July 7, due to a significant reduction in rainfall, the water needs of the plants under rainfed conditions were not met, resulting in substantial decreases in grain and biomass yields due to drought stress and insufficient moisture supply. Furthermore, the results of the interaction between species and sowing date indicated that pearl millet cv. Mehran had a higher potential for grain and biomass yields compared to proso millet cv. Pishahang. For pearl millet, the highest grain and biomass yields were achieved on the sowing dates of June 4 (1365.76 kg/ha) and July 7 (1290.91 kg/ha). For proso millet cv. Pishahang, the highest grain and biomass yields were recorded on June 4, with an average of 1165.66 kg/ha and 6349.91 kg/ha, respectively. Overall, the findings of this experiment demonstrated that pearl millet (cv. Mehran) outperformed proso millet (cv. Pishahang) in all evaluated traits.
Conclusion: The lack of significant differences in grain and forage yields of pearl millet sown on June 4 under both rainfed and irrigated conditions suggests optimal synchronization of the plant's growth stages with favorable environmental conditions. Therefore, it is recommended to cultivate pearl millet (cv. Mehran) under rainfed conditions with a sowing date of June 4 to conserve water.