Growth and Yield of Millet (Panicum miliaceum L.) as Affected by Different Levels of Organic Fertilizer and Zinc Sulfate

Introduction:Millet (Panicum miliaceum L.) is a ,warm-season grass with a growing season of 60–100 days. It is a highly nutritious cereal grain used for human consumption, birdseed, and/or ethanol production. Millet ranks sixth among the world’s most important cereal grains, sustaining more than one-third of the world’s population. Millets are generally among the most suitable crops for sustainable agriculture and food security on marginal lands with low fertility. Millet crops are grown on marginal lands and under low-input agricultural conditions, situations in which major cereal crops often produce low yields. Foliar application of Zn brings the greatest benefit in comparison with addition to soil where they become less available. Generally, Micronutrients are essential for plant growth and play an important role in balanced crop nutrition. Micronutrients are as important to plant nutrition as primary and secondary nutrients, though plants do not require as much of them. Materials and methodsTo study the effect of cow manure (CM: 0, 10, 20, and 30 ton ha-1) and zinc sulfate (ZS: 0, 60, and 90 kg ha-1) application on common millet (Panicum miliaceaum L.) growth and yield, a factorial experiment based on a randomized complete block design (RCBD) with three replications was conducted in the research field of University of Birjand, Iran, in 2018 growing season. In addition, a chemical fertilizer (NPK) treatment was considered in each block, and its effect was compared with 12 other combination treatments based on a randomized complete block design.  The studied traits were plant height, number of tillers per plant, 1000-grain weight, grain yield, biological yield, harvest index, and seed zinc content. The software SAS (V9.1) and Excel were used to analyze the data and draw the figures. Means were compared using the FLSD test at a 5% probability level. Result and discussion:Analysis of variance results showed that the simple effects of both experimental factors were significant on all studied traits, but none of the interaction effects were significant. Application of 60 kg ha-1 of ZS improved all growth and yield parameters of millet, while the highest zinc content in the seed was obtained by applying 90 kg ha-1. The highest seed and biological yields (2227 and 7940 kg ha-1, respectively) were obtained by 60 kg ha-1 of ZS application, which was 36 and 6.6% higher than the control treatment (no-fertilization), respectively. All studied traits showed an increasing trend with increasing the amount of CM consumption, so that their highest values ​​were obtained when 30 tons ha-1 of CM was applied. Seed yield (2564 kg ha-1) at the highest CM level was 138% more than the control treatment and ultimately led to a 14.4% increase in the harvest index. Conclusion:Millet (Panicum miliaceum L.) is a cereal plant cultivated for its grain, mostly in Asia and North America. It is a warm-season grass with a short growing season and low moisture requirement that is capable of producing food or feed where other grain crops would fail. Chemical fertilizer treatment (NPK) also improved all traits related to plant growth and yield compared to control as well as some other fertilization treatments. Modifying the physical properties of the soil and the availability of nutrients for millet plants can be a major reason for the increased yield and growth of the plant. Also, the results showed that consumption of zinc sulfate at 60 kg.ha-1 increased yield and yield components of common millet, but consumption of 90 kg.ha-1 of this fertilizer reduced the studied traits. In addition, the results of this experiment showed a significant difference between four levels of manure so that the highest grain yield of studied millet was obtained from 30 tons per hectare of manure. According to the test results, it can be stated that the application of zinc sulfate at a rate of 60 kg per hectare increased the yield and yield components of millet and therefore is introduced as the desired amount of fertilizer to achieve ideal yield.