Evaluation of oil content, oil yield and chlorophyll content of grain at different maturity stages in rapeseed cultivars

To evaluate rapeseed grain quality at different maturity stages, an experiment was conducted in the experimental field of Seed and Plant Improvement Institute, Karaj, Iran in 2003-2005 grwoing seasons. Six commercial rapeseed cultivars including; Okapi, Orient, Zarfam, Opera, Licord and SLM046 and five harvesting times including; 50%, 60%, 70%, 80% and 90% siliques maturity of the main stems were studied-using split plot arrangement in randomized complete block design with three replications. Cultivars were assigned to main plots and harvesting times were randomized in in sub-plots. Chlorophyll contents, oil yield and oil and moisture content of the grain were determined by standard methods. Combined analysis of variance revealed taht the differences among cultivars for the measured traits were significant (P<0.01). Okapi had the lowest chlorophyll content (2.3 mg.kg-1) and the highest oil yield (1661 kg.ha-1) and was superior to other cultivars. Okapi also had the highest (48.7%) oil content. Effect of harvest time on measured traits were significant (P<0.01). Harvesting in 80% maturity of siliques had the lowest (1.9 mg.kg-1) chlorophyll content while the highest oil yield (1548 kg.ha-1) belonged to 90% maturity of siliques. Cultivar × harvest time effects on chlorophyll and moisture contents were significant (P<0.01). Direct and indirect harvesting are suggested at 90% and 70-80% maturity of siliques to maximize grain quality and minimize yield losses.