عنوان مقاله [English]
Background and Objectives
The cropping pattern will influence the crop yield due to better use of light, better crop arrangement within and between rows, and also higher access to soil nutrients (Weiss, 2000). In sesame, high water use efficiency was gained when it was planted over and even under rows rather than when it was planted as a flat form (Aggarwal, 2003). Also, biofertilizers could compensate some of the plant’s need for nutrients like nitrogen, but apparently, it’s not sufficient. So the integrated chemical and biological fertilizer will increase plant height, pod per plant, 1000 seed weight, and grain yield (Kumar et al., 2009). Therefore, the goal of this research is the evaluation of the effect of PGPR as an integrated fertilizer management and planting method on sesame yield quantity and quality.
Materials and Methods
This study was carried out at the summer of 2016 in the experimental field station of Agricultural Faculty of Shahid Chamran University of Ahvaz. The experimental design was a split plot based on RCB with three replications. Three planting methods placed on the main plot and sub-plot, including four fertilizer management. Sesame grain yield and yield components were measured. The data were subjected to ANOVA with SPSS and Duncan test was used to distinguish the mean differences which were significant.
Results showed that the maximum pod per plant (177 cm), biological yield (5110 kg ha-1), grain yield (1825 kg ha-1), and harvest index (35.7 %) were obtained from the alternative planting on the top row with full chemical fertilizer management. Chlorophyll index was significantly affected by the fertilizer methods. While comparing the chlorophyll index between chemical (56) and the integrated 1and 2 (44 and 48) fertilizer management, it became evident that the decline of chemical nitrogen caused a significant reduction in this index. In other words, applying a biological fertilizer or the activity of PGPRs can’t compensate for the effect of chemical N reduction. In following, reducing the chlorophyll content likely had a negative effect on the plant photosynthesis potential which caused lower 1000 grain weight in integrated treatments than the full chemical fertilizer method. In addition, the planting method had no significant effect on oil percentage, but the highest and lowest oil yield belonged to the alternative planting on the top row (710 kg ha-1) and planting under row (482 kg ha-1), respectively. Based on our data, the change in panting method had no significant effect on oil percentage, but applying chemical N had significantly increased the oil percentage. Also, planting on top of the row increased both oil percentage and grain yield, which had direct positive effects on oil yield. Both oleic and linoleic acid were increased more by PGPRs than chemical N form, but these unsaturated fatty acids were not significantly affected by the planting method treatment.
We find that both the highest grain yield (1441 kg ha-1) and oil percentage (52.24%) belonged to the planting a row on top of row treatment. Between the integrated fertilizer management, the heights (1674 kg ha-1) and lowest (1068 kg ha-1) grain yield belonged to the full chemical fertilizer and integrated 1 treatment, respectively. In contrast, both oleic and linoleic acid were the highest at integrated fertilizer management in all planting methods with chemical treatment. We concluded that the present sesame cultivars are more adaptive to high-input systems, so we must be breeding new cultivars which are more suitable for sustainable agriculture.