Evaluation of the effect of planting date and plant density of maternal plant on the quality and germination characteristics of Guar seed (Cyamopsis tetragonoloba) in Guilan province

Guar (Cyamopsis tetragonoloba L.) is an annual, dicotyledonous plant of the legume family, also known as cluster beans. This plant can tolerate salinity and drought stress well. Optimal planting date and plant density are factors affecting the quality and quantity of crops. The distribution of plants in the field influences the absorption and productivity of environmental factors affecting the growth and intra- and inter- competition and eventually is one of the factors determining the quantity and quality of yield. Different planting dates set off different conditions in terms of temperature day length, relative humidity, solar radiation, ripening and harvest time and thus, affect the quantitative and qualitative characteristics of seeds. The purpose of this experiment is to evaluate the quality and also to evaluate some of the germination characteristics of Guar seeds at different dates and planting densities under the climatic conditions of Guilan.

This experiment was conducted in the spring and summer of 2017 in the research farm of Rasht Rice Research Institute located in Gil Pardehsar village at Sangar as a factorial based on a randomized complete block design with three replications. Experimental treatments included four planting dates (12 May, 26 May, 9 June and 23 June) and three plant densities (20, 40 and 60 plants. m-2). Seed harvesting was done as the pods in 75% of the plants in each plot turned brown and traits such as germination percentage, germination rate, root and shoot length and fresh and dry weight of roots and shoots, longitudinal index of seedling vigor, 1000- grain weight, electrical conductivity and alpha-amylase activity were investigated.

The results of the present study showed that guar seeds had the highest quality on 26 May and a density of 40 plants.m-2. Due to favorable climatic conditions during the period of seed filling, germination rate, germination percentage, seedling vigor index, root length and 1000- grain weight was high on 26 May. The amount of these traits decreased with delay in planting. The amount of electrical conductivity in 23 June date of planting treatment showed the highest value. The highest level of alpha-amylase activity was observed on 9 June.

In general, it can be concluded that the best planting date and plant density of guar seeds in Guilan province with the highest quality of seeds and germination is on 26 May and 40 plants.m-2.