Evaluation of yield and some physiological characterictics of borage (Borago officinalis L.) under plant density and sowing dates in Ahwaz region

In order to study the yield and some physiological characteristics of borage (Borago officinalis L.) under different plant densities and sowing dates in Ahwaz city, an experiment was carried out in a split plot arrangement based on randomized complete block design with three replications in Khuzestan Ramin Agriculture and Natural Resources University, Iran during 2016-2017. The treatments included sowing date as main plot in five levels (15 October, 5 November, 25 November, 15 December and 5 January) and plant densities as sub-factor in four levels (6, 10, 14 and 18 plant per m2) were considered. The results showed that delayed sowing (5 January) caused anincreased temperature at flowering stage and significantly reduced the grain yield and biological yield (182.22 and 1443.4 kg ha-1, respectively). The sowing dates of 5 November at a density of 10 plants/m2 caused the highest grain yield and oil yield with average values of 1243.82 and 437.47 kg ha-1, respectively. The sowing date of 15 October at a density of 14 plants/m2 caused the highest chlorophyll a and total chlorophyll content with average values of 1.13 and 3.39 mg/g fw, respectively. A delay in sowing date from 15 October to 5 January led to a decreased relative leaf water content, cell membrane stability and chlorophyll content. High plant density per m-2 increased the plant height and biological yield and reduced the oil percentage. Sowing date had significant effects on all traits expect oil percentage.