Effects of planting density and chemical fertilizer on qualitative and quantitative characteristics of guar (Cyamopsis tetragonoloba L.), a medicinal-industrial plant

In order to determine the effect of fertilizer and plant density on qualitative and quantitative characteristics of guar (Cyamopsis tetragonaloba L.), a medicinal-industrial plant, a factorial experiment was conducted in a randomized complete block design with three replications in 2015 and 2016 crop years. Fertilizer was considered as the first factor at two levels of 60-70-70 and 90-100-100 kg ha-1 nitrogen, phosphorus, and potassium, respectively, and the second factor was planting density at three levels of 60, 75 and 90 plants per m2. The results showed that in the first year, the effect of fertilizer treatment levels was not significant on the traits studied except seed swelling trait. Planting density affected the number of pods significantly (1%), but had no significant effect on other traits. The interaction of fertilizer and plant density was significant on mucilage production. In the second year, the effect of fertilizer was significant only on biomass and mucilage production. Also, the effect of planting density was significant on biomass and the number of pods, and the interaction of fertilizer and planting density was significant only on the amount of mucilage. The mean comparison indicated the increase in biomass and seed yield in the second year in both factors. By reducing the plant density, the number of branches and pods per plant increased, which increased the yield. In the second year, the amount of crude protein and seed mucilage increased and decreased, respectively. In this study, the amount of seed swelling was not positively correlated with the mucilage amount. Regarding the results of the present study, as well as guar as a legume, and the possibility of supplying part of the plant nutritional needs by the plant itself, if the purpose is mucilage production, the 60-70-70 fertilizer treatment and 60 plants per m2 are recommended under similar conditions to this research.