Effect of organic and chemical fertilizers on growth indices, yield and yield components of Guar in different plant densities

Guar or cluster bean belongs to leguminosae family. It is an annual plant and tolerant to salinity and drought. Guar is a drought resistant plant which is cultivated as a forage and seed crop and vegetable in warm and dry regions of Asia and Africa (Momen Keykha et al., 2018). The use of organic matters as fertilizer on agricultural soils can reduce the effects of soil compaction and provide the nutrients for the plants (Mohammadnejad et al., 2015). The research on the use organic fertilizers on guar under different plant densities has been scant. Thus the present study was carried out in order to assess and survey the effects of nutritious factors and density on growth indices, yield and yield components of Guar under Isfahan climatic conditions.

Experiment was conducted as factorial using randomized complete blocks design with three replications. This research was carried out during the growing season of 2015-2016 in the center of agricultural research of Isfahan province. First factor included: chemical fertilizer (two levels of 60, 70, 70 and the other 90, 100, 100, kilograms per hectare respectively nitrogen, potassium and phosphorous), animal manure (in two levels 10 and 20 tons per hectare) and vermicompost (at two levels of 300 and 600 kilograms per hectare) and density as the second factor consists of three levels of 60, 75 and 90 plants / m2. Growth indices were LAI, CGR and RGR. Also plant height, number of branches, pod number per plant, grain number per pod, length of pod, 1000-grain weight and grain yield were measured. The data were statistically analyzed by SAS software. Comparison of means was performed using LSD test at the 0.05 level of significant.

The highest LAI belonged to chemical fertilizer 2 and the lowest to vermicompost 1. 60 and 90 plants per square meter had the highest and lowest LAI respectively. The highest and lowest CGR belonged to chemical fertilizer and vermicompost respectively. CGR peaked in all the treatments by appearance of pods and reduced while pods were filling. This can be due to increasing shades and lack of light (Emam and Niknejad, 2011). RGR was almost linear and declining. They decreased to zero and negative.The results showed that the effect of factors were significant on all traits except grain number per pod and 1000-grain weight. Based on the results, the plant height, number of sub branches, number of pods, pod length and grain yield in nutritious treatments and plant density were significant, but the interaction between fertilizer levels and density, except for the number of pods, were not significant. The maximum number of sub branches (6.13), pod number per plant (46.32), 1000-grain weight (33.55 g) and grain yield (3646.3 kg/h) was observed in density of 60 plants per square meter. Rezvani Moghaddam et al., (2010) reported that the seed yield was increased by increasing plant density, but decreased the plant height, number of capsule per plant, plant biomass, seed yield and weight and number of seed per plant, significantly. 1000-seed weight, harvest index and weight of seed per capsule had no affected by treatments. Asadi et al., (2013) reported that organic input application could be considered as a sustainable approach for improving growth and yield of medicinal plants such as isabgol in agroecosystems that will increase nitrogen efficiency and reduce environmental pollutions due to slow release of nutrients.

As a whole the density of 60 pl/m2 was preferred in most of traits. In most of the yield components, preference is to chemical fertilizer, but in the some traits, vermicompost was at the same level or sometimes superior to other treatments. So at the same condition, it is advisable to use 60 plants per square meter and to get a better result in cropping and to decrease the negative environmental effects, it is advisable to use a combination of chemical fertilizer and vermicompost.