The Effect of Planting Arrangement of Nitrogen and Phosphorus on Yield and Physiological Traits of Guar (Cyamopsis tetragonoloba L.) in Iran

To study the effect of planting arrangement of nitrogen and phosphorus on yield and physiological traits of guar, a factorial experiment in a randomized complete block design with three replications in two cropping years 2019-20 and 2020-21 in the research center and agricultural and natural resources education of southern Kerman was implemented. Nitrogen at three levels (20, 60, and 100 kg pure nitrogen per hectare) from urea and phosphorus fertilizer source at two levels (zero and 75 kg P2O5 source per hectare) from monopotassium phosphate fertilizer source and planting row spacing at three levels (30, 45 and 60 cm) equivalent to 47, 31 and 24 plants per square meter, plant density were considered. The results showed that nitrogen, phosphorus, and planting density significantly affected all traits. Planting row spacing affected all characteristics except seed gum and phosphorus levels were effective on all traits except glycine betaine and leaf sodium. The highest yield components and seed gum were obtained from N3P2D3 treatment (application of 60kg/ha nitrogen, 75 kg/ha phosphorus, and 60 cm row spacing) which was no different from N2P1D3 treatment and the highest leaf proline content was related to N2P2D3 treatment and the highest glycine content was betaine and leaves. Sodium was related to N2P1D3 treatment. The highest grain yield and yield components in the first and second year of N2P2D2 treatment (application of 60 and 75 kg of nitrogen and phosphorus, respectively, with a row spacing of 45 cm) were obtained at 4300 and 4200 kg/ha, respectively, with N3P1D2 and N3P2D2 was not significantly different. The highest levels of carotenoids and chlorophyll a and b were related to N3P2D3 treatment. Based on the results of this study, it seems that this plant does not need high levels of nitrogen and phosphorus in terms of legume, but is affected by nitrogen and phosphorus for high yield and product quality. Regarding row spacing, if the goal is to achieve a high yield, row spacing of 45 cm and high quality 60 cm spacing is recommended and can be considered as a low-expectation plant in the cultivation pattern program in the climatic conditions of southern Kerman