Effect of plant density and temperature on yield and morpho-physiological traits of garlic (Allium sativum L.)

In order to investigate the effects of different temperatures and also plant density on yield and some of morpho-physiological traits of garlic (Allium sativum L.), a split plot experiment was conducted based on randomized complete blocks design with three replications. Experimental treatments were three spring planting temperatures (7.4, 9 and 11°C) and four planting densities (20, 40, 60 and 80 plant m-2). Based on results, the interaction effect of experimental treatments on garlic yield, leaf weight, plant height, total chlorophyll and carotenoids was significant whereas for harvest index, number of produced cloves in plant, chlorophyll a and relative water content only the effects of temperature and plant density were significant. The highest garlic yield (921 g.m-2) was observed in planting temperature of 7.4°C with a density of 80 plants m-2, but the lowest yield (317 g.m-2) was obtained in the planting temperature of 11°C with the lowest plant density. The same results were also observed for leaf weight. The highest amount of chlorophyll (2.52 mg.g FW-1) was observed in the planting temperature of 9°C with the density of 20 plants m-2but the planting density of 80 plants m-2 in the planting temperature of 11°C resulted in the lowest amount of total chlorophyll (2.07 mg.g FW-1). The highest harvest index was related to the planting temperature of 7.4°C, and with delay in planting date, this index was reduced significantly. The lowest number of cloves per plant (3.64) was related to the planting temperature of 11°C. Increasing plant density also decreased the number of produced cloves by 14 percent. The best planting temperature for the highest garlic yield was 7.4°C. Although in all of the planting temperature treatments, increasing the plant density resulted in higher garlic yield, the positive effects of higher densities were mainly observed in the planting temperature of 7.4°C.