a comparison of yield, harvest index and morphological characters of spring cultivars of the oilseed rape species

yield, harvest index and morphological characters of 13 spring cultivars of rapeseed were evaluated in 2007 growing season at agriculture and natural resources research station of torogh, mashhad. these cultivars were from three rapeseed species belonged to brassica napus, brassica rapa and brassica juncea. experimental design was randomized compelet block with four replication. result showed that significant difference occurred within cultivars for yield and harvest index. hyolla 330 with average of 1475 kg.ha-1, bp18 with average of 1277 kg.ha-1 and hyolla 401 with average of 1274 kg.ha-1 had respectively most yield in this trial. obviously hyolla hybrids had more relative superiority than other cultivars regarding harvest index. cultivars of b.napus had more both yield and harvest index than b.rapa cultivars. the examination of morphological characters, including chlorophyll content and stomata density and height, showed that considerable difference existed among cultivars. rate of chlorophyll enhanced increasingly at tow intervals of sampling because of leaves development. strongly positive correlation observed between yield and harvest index (r = 0.75**). among morphological characters positive correlation was obtained between yield and height (0.34*). considrable correlation which was between chlorophyll content and yield, was'nt very noticeable (r = 0.27*).