Conjunctive effect of harvesting date and supplementary irrigation in different growth stages on peanut (Arachis hypogaea L.) under rainfed conditions

Abstract

This experiment carried out as split factorial based on randomized complete block design with three replications in the experimental field of the Agricultural and Natural Resources Research and Education Center of Guilan Province, Astara, Iran. Four levels of irrigation including rain-fed condition (IR₀), irrigation at the flowering stage (IR_F), irrigation at the pod formation stage (IR_P), and irrigation at the flowering stage + irrigation at the pod formation stage (IR_F + IR_p) in the main plot and three levels of harvesting date inclusive of August 22 (HD₁), September 6 (HD₂) and September 21 (HD₃) in the sub plot, comprised experimental treatments. Result indicated that all measured physiological characteristics improved under supplementary irrigation conditions except unsaturated oleic acid and saturated palmitic acid. The greatest biological yield (8091.67 kg ha^− 1), seed yield (2375 kg ha^− 1), oil yield (1181.60 kg ha^− 1), protein yield (458.33 kg ha^− 1) and unsaturated linoleic acid (30.94%) were obtained in response to (IR_{f +} IR_p) _× HD₃ interaction. Hence, two stages of supplementary irrigation (IR_{f +} IR_p) and late harvesting date (HD₃) increased biological yield by 64.26%, seed yield by 32.33%, oil yield by 76.88% and protein yield by 63.31%. Whereas, the greatest unsaturated oleic acid (58.35%) was achieved in the first harvesting date (HD₁) and rainfed conditions and the quality of peanut oil enhanced in response to water deficit. Generally, the results revealed that the supplementary irrigation had great potential for increasing plant growth period and improving peanut yield under rainfed conditions. Hence, supplementary irrigation along with delay in harvesting date could be recommended to increase crop productivity and sustainability of peanut yield under rainfed conditions.