Effect of farmyard manure and green manure application on yield, yield components and grain oil content of Sesame (Sesamum indicum L.) under organic conditions

The cultivation area of sesame is about 43,000 hectares and the average yield is 900 kg ha-1 (Anonymous, 2017). Due to low grain yield of sesame per unit area, need to field operations are felt. To achieve high yield, it is necessary to manage production inputs in order to use them correctly and efficiently (Tahmasebi & Mostafavi, 2010). The use of renewable farmyard and green manures instead of chemical sources in crop rotation can play an important role in fertility and preservation of biological activities, soil organic matter, ecosystem health and crop quality (Zaidi et al., 2003). Farmyard manure provides all plant nutrients in limited quantities. The nutrient elements of farmyard manure (nitrogen, phosphorus, sulfur, iron, zinc) are slowly released to the plant, thus causing less pollution in the environment. In organic farming, the use of legumes as a green manure has also been a matter of interest due to their ability to stabilize atmospheric nitrogen. This study was conducted to evaluate the effect of farmyard manure and green manure application on grain and grain components of sesame under temperate Kermanshah region condition.

This experiment was done in the Organic Farming Educational and Research of Campus of Agriculture and Natural Resources at Razi University, Kermanshah, Iran during 2016-2017. The farm of study was located in latitude 34º21'North and longitude 47º9' East with 1319 m above sea. The experiment was conducted as split plot based on randomized complete block design with three replications. The experimental treatments included farmyard manure at three levels (0, 10 and 20 t h-1, FM0, FM10 and FM20, respectively) as the main factor and the cultivation of green manure (non-cultivating green manure, hairy vetch, berseem clover and fenugreek) as sub factor. At the end of growing season, number of branches per plant, number of capsules per plant, number of grain per capsule, 1000-grain weight (g), total dry weight yield (kg ha-1), grain yield (kg ha-1), harvest index (%) and grain oil content (%) were measured for each plot. Statistical analysis and means comparison by LSD method at 5% level were performed using SAS software.

Based on the results, in FM10 and FM20 treatments, the number of branches per plant 20 and 21%, capsule per plant 10.9 and 30.7%, 1000-grain weight 4.2 and 5.5%, total dry weight yield 25 and 34%, and grain yield 18.8% and 38.1% were higher than FM0 treatment, respectively. The application of green manure also improved sesame and yield and yield components, but the difference between various species of green manure was not significant. However, the highest and had the least effect on these traits were related to fenugreek and hairy vetch, respectively. Application of green manure at all levels of farmyard manure also increased total dry wieght yield and grain yield of sesame. The maximum of 1000-grain weight, total dry weight yield and grain yield (3.3 g, 10720 and 1929 kg ha-1, respectively) were obtained in FM20 and planting the fenugreek as green manure, their lowest amounts (2.87 g, 5960 and 918 kg ha-1, respectively) were obtained under control conditions. Effective traits on sesame grain yield were number of capsules per plant (0.81), 1000-grain weight (0.75) and number of grain per capsule (0.35), respectively. The correlation between total dry weight yield and number of capsules per plant (0.62), 1000-grain weight (0.57), and number of branches per plant (0.54) was positive and significant at 1% level. There was a positive and significant correlation between dry weight and grain yield (0.78) at 1% level. Grain oil content was not positively correlated with any of the traits and showed the most negative and significant correlation with grain yield (-0.42).

In general, the results indicate that farmyard manure application and select the appropriate green manure species by provide a balanced composition of nutrients is an appropriate solution to improve sesame yield and yield components, so sustainable production of sesame is possible in organic farming systems.