Response of qualitative yield and fatty acids combination in groundnut oil to intercropped system with corn and combined application of chemical phosphorus and bio-fertilizers

Intercropping is a possible pathway for sustainable increases in crop yields (10). Researchers have reported that intercropping system with legumes led to maximum maize gain (24) and biological yield (4). Ghasemi et al. (2011) reported that grain yield in maize was the highest when the combination of chemical and bio-fertilizers were used (8).

This experiment was performed as factorial arrangement based on randomized complete block design in 2017 and 2018 cropping deasons with three replications in Rasht, Iran. Five rate of phosphorus fertilizer (zero, 50, 100 kg/ha as super phosphate triple, 50 kg/ha as super phosphate triple + 200 g phosphate barvar2 and 100 kg/ha as super phosphate triple + 200 g of phosphate barvar2) and corn and groundnut sol cropping, and mixed cultivation of one row of corn + one row of peanuts (1: 1), two rows of corn + one row of peanut (1: 2), one row of corn + two rows of peanut (2: 1) comprised experimental treatments.

In this experiment, phosphorus fertilizer × intercropping system effect on all measured characteristics was significant at 5 % probability level. The greatest grain yield (2360 kg/ha), oil yield (1182 kg/ha), grain protein percentage (27.70 %), protein yield (591 kg/ha) and palmitic acid (10.58 %) were obtained in response to the application of 100 kg/ha super phosphate triple along with 200 g phosphate barvar2 bio-fertilizer under groundnut sol cropping system. The greatest grain oil percentage (53.45 %) and oleic acid (66.63 %) as the most important unsaturated fatty acid in groundnut oil were obtained in response to the application of 100 kg/ha phosphorus fertilizer as super phosphate triple, under groundnut-corn intercropping system with the ratio of 1:2 planting rows. But, the highest rate of linoleic acid (32.17 %) was observed in groundnut-corn intercropping system with the ratio of 1:1 planting rows as affected by the application of 100 kg/ha phosphorus fertilizer as super phosphate triple plus 200 g phosphate barvar2 bio-fertilizer.

Results showed that the combined application of chemical phosphorus and bio-fertilizers enhanced groundnut grain yield that could causes by the improvement of yield components, enhancement of plant growth and nutrients absorption and increment of photosynthesis in groundnut plants. Apart application of chemical phosphorus fertilizer increased oleic acid synthesis and quality of groundnut oil. The application of chemical phosphorus fertilizer and groundnut-corn intercropping system with the ratio of 1:2 improved groundnut oil quality. But, integrated application of chemical phosphorus (super phosphate triple) plus phosphate barvar2 bio-fertilizer enhanced quantitative yield of groundnut. In this experiment, groundnut-corn intercropping system with the ratio of 1:2 and integrated application of chemical phosphorus plus phosphate barvar2 bio-fertilizer could be recommendable to enhance grain yield of groundnut per unit area.