Investigating the Effect of Organic Fertilizers Municipal Waste Compost and Orange Waste Compost on Growth and Yield of Common Millet (Panicum miliaceum L.)

IntroductionCommon millet (Panicum miliaceum L.) belonging to the family Gramineae is a warm-season grass with a growing season length of 60–100 days. It is specially adapted to hot summers in the tropics and high altitudes, where the growing season is short, and the soil is poor in fertility. Among grain crops, common millet has the lowest water requirement and can grow on any type of soil except coarse sand. Therefore, appropriate management of common millet is necessary to maximize yield and yield components. Organic matter is one of the most important constituents of soil, significantly affecting the availability of nutrients and improving the soil's physical, chemical, and biological properties. Therefore, the purpose of this study was to evaluate the effects of different levels of municipal waste compost and orange waste compost on vegetative, reproductive growth, and yield of common millet.Materials and MethodsThe experiment was designed as a factorial arrangement based on a randomized complete block design with three replications under field conditions in Gonabad during the growing season of 2018. Treatments were three levels of municipal waste compost (0, 7.5, and 15 t.ha-1) and three levels of orange waste compost (0, 7.5, and 15 t.ha-1). The measured indices including vegetative characteristics (plant height (cm), number of tillers per plant, plant dry weight (g.plant-1), number of leaves per plant, panicle height (cm)) and reproductive characteristics (seed yield per plant (g), 1000-seed weight (g), seed yield, biological yield (kg.ha-1) and harvest index). Finally, the experimental data were statistically analyzed using the SAS program ver. 9.1 and comparison of means was performed by LSD test at 5% probability level.Results and DiscussionThe results showed that with increasing use of municipal waste compost as well as orange compost in soil, plant height, dry weight and grain yield and harvest index increased. The highest amount of municipal waste compost (15 t.ha-1) and orange waste compost (15 t.ha-1) increased the plant height by 15.8 and 11.8 percent, respectively, compared to control. The reason for the increase in plant height due to the use of organic materials is due to the improvement of the chemical and physical properties of the soil, the increase in the storage capacity of nutrients, and the preparation of the ground bed for better root growth in the soil. The maximum dry-weight plant was obtained in the treatment of municipal waste compost (15 t.ha-1) and orange waste compost (15 t.ha-1). The nitrogen present in organic fertilizers enhances vegetative growth, and the high potassium in these fertilizers, in addition to accelerating cell division and directly affecting vegetative growth due to its role in the production of carbohydrates and proteins and the concentration of cell sap, increases the dry weight of the plant. The highest seed yield was observed at the level of 15 tons per hectare of municipal waste compost, with a 60.2% increase compared to the control, and at the level of 15 tons per hectare of orange waste compost, with an increase of 37.4% compared to the zero level. Also, the simple effect of municipal waste compost and orange waste and the interaction of two treatments on grain weight per plant, 1000-seed weight, biological yield, and harvest index were significant. The highest seed weight per plant was obtained from the highest levels of municipal waste compost and orange waste (15 t.ha-1 + 15 t.ha-1). The highest 1000-seed weight and biological yield were observed in the treatment of municipal waste compost (15 t.ha-1) and orange waste compost (15 t.ha-1). Also, the highest harvest index was related to the treatment of municipal waste compost (15 t.ha-1) and orange waste compost (7.5 t.ha-1). Probably, the availability of more nutrients for the plant has led to an increase in the production of photosynthetic materials for the seeds and, as a result, an increase in their weight.ConclusionThe results of this study showed that municipal waste compost and orange waste compost had a significant effect on the yield and growth characteristics of common millet. Thus, results showed that municipal waste compost (15 t.ha-1) and orange waste compost (15 t.ha-1) had a strong impact on the yield and growth characteristics of common millet under field conditions.