Physiological and harvest maturity of canola in relation to seed quality

The ability to identify physiological (PM) and harvest maturity (IM) of canola (Brassica napus L.) by phenological characteristics would permit timely harvest to avoid problems of both under- and overripe pods. This study was conducted to identify PM and HM of six winter and spring canola cultivars using morphological and physiological markers including seed and pod color, seed dry weight (DINT), seed moisture content (SMC), and to measure seed quality (germination and vigor) at PM and HM. Pods and seeds from each cultivar were sampled at weekly intervals from pod formation until HM. Standard germination, accelerated aging, and cold tests were conducted to assess seed quality. Canola attained PM when pods turned from green to greenish-yellow or light brown, and contained seeds ranging from brownish green to greenish brown and light brown. The seeds were firm, Seed DWT did not change significantly from PM to HM. Seed NIC at maximum DWT ranged from 203 to 360 g kg(-1). Pods at HM were yellow to brown and the seeds were brown or dark brown to black, depending on the cultivar. The SMC was near 100 g kg(-1) and the seeds were hard and rattled inside the pod. Seeds of all cultivars had greater germination and vigor at HM than at PM. Canola can be harvested 2 wk before reaching HM without affecting yield; however, SMC at this stage is not suitable for direct harvest and seed quality is not at the highest level.