​Effect of Irrigation Regimes and Phosphorus Fertilization on Water-use Efficiency, Phosphorus-agronomic Efficiency and Yield of Grass Pea (Lathyrus sativus L.) Ecotypes

Abstract

Background: Grass pea (Lathyrus sativus L.) is a crop of immense economic significance. It is one of the most resilient to climate changes and to be survival food during drought-triggered famines. Methods: In a field study split factorial experiment based on a randomized complete block design with 3 replications were used, effects of irrigation regimes (50, 75 and 100% evaporation of Pan class A) and different rates of phosphorous fertilizer (triple superphosphate 0, 60 and 120 kg/ha) on growth and yield of two grass pea ecotypes (Lalehzar and Sharekord) in Lalezar area (Kerman province, Iran) was carried out during 2018 and 2019. Result: The results showed that drought stress reduced grass pea seed yield (401 kg/ha-1) and biological yield (863 kg/ha-1) and this reduction was depended on the severity of stress. In the other side, application of phosphorous fertilizer (60 kg/ha-1) increased grass pea yield (2401 kg/ha-1). This means that phosphorus fertilizer could partiaiiy offset the effect of drought stress and had a significant effect on the water use efficiency and phosphorus agronomic efficiency. Finally, drought stress, either no-application phosphorus fertilizer, could decrease yield. Overally, Shahrekord ecotype showed the higher and most desirable grain yield (2401 kg/ha-1), biological yield (5612 kg/ha-1), grain water use efficiency and biological water use efficiency, respectively, with (0.74 and 1.72 m3 water/ha-1) and phosphorus agronomic efficiency (18.76 kg yield/kg P) to the applied treatments (75% irrigation+ triple superphosphate fertilizer 60 kg/ha).