Sesame (Sesamum indicum L.) Response to Different Fertilizing System and Cover Crops in Weed Competition

This study was conducted to investigate the effect of different nutrition systems and cover crops on morphological traits, yield, yield components and competitive indices of sesame in competition with weeds.  

This research was carried out in the research farm of Sari Agricultural Sciences and Natural Resources University in 2016 as a randomized complete block design with three replications and eight treatments. Experimental treatments include: 1- sesame + soybean cover crop + without fertilizer, 2- sesame + millet cover crop + without fertilizer, 3- sesame + soybean cover crop + vermicompost, 4- sesame + millet cover crop + vermicompost, 5- sesame + soybean cover crop + chemical fertilizer, 6- sesame + millet cover crop + chemical fertilizer, 7- sesame + without weeding + without fertilizer (control) 8- sesame + weeding + chemical fertilizer (control). Also, two treatments of monoculture of sesame were considered as control (weed infestation and weed free). The traits studied in this experiment include weed density and weed biomass, competitive indices, yield and yield components, as well as morphological traits of sesame. 

The results of weed sampling in three stages (10- leaf, seed dough and harvesting time) showed that the highest weeds density and biomass was in control with weed infestation and then in soybean cover crop with chemical fertilizer application. The results showed that fertilizer resources and cover crops had a significant effect on the grain yield, number of capsules per plant, seed number per capsule, 1000 seed weight, biological yield, as well as competition index (CI), so that the highest and lowest grain yields were observed in the treatment of millet with organic fertilizer (1630.22 kg.ha-1) and millet without fertilizer (413.33 kg.ha-1), respectively. The highest number of capsules per plant (41) was observed in weed control and the highest number of seeds per capsule (64.33 and 63.66) and 1000-seeds weight (2.56 and 2.53 g) in two treatments of weed control and millet cover crop with organic fertilizer application, respectively. Also, the highest rate of competition index (4.38%) was observed in millet cover crop with organic fertilizer, which showed significant effect of treatments on this index in sesame. 

The result of this experiment showed that millet cover crop, with decreasing weed density and biomass, increased sesame yield significantly. Furthermore, the use of organic fertilizers comparison to chemical fertilizers improves the properties of the soil and, also, the use of these fertilizers with the appropriate cover crops is a suitable strategy for sustainable agriculture in order to achieve greater yield and higher quality of the sesame. So, use of millet cover crop as well as organic fertilizer is recommended to improve sesame yield and proper weed management.