Physiological Mechanisms Of The High Boron Efficiency In Brassica Napus

Responses of oil rape (Brassica napus) to low boron (B) stress varied greatly in species, it's very important to study the physiological and genetic mechanisms of tolerance to low B stress for providing the base of genetic improvement of rape and oil crops production in China. In the study, the mechanisms and genetic characters of high B efficiency were studied with typical high or low B efficiency cultivars of oil rape which was screened and identified by Wang et al, and the main results were shown as followed:1. The production and quality of rapeseed were affected by low B stress (the available soil B is 0.25mg/kg) with a decrease of 45% for seed yield, and glucosindate content and erucic acid were also decreased when it suffered low B stress, however, oil content and oleic acid content showed an increased tendence. B efficient coefficient had no significant correlation with glucosindate content, erucic acid, oil content and oleic acid of rapeseed.For high B efficient cultivar, the higher free water content in plant under optimum soil water content condition, and the increased semi-bound B content under low B stress condition, were beneficial to B transportation. For low B efficient cultivar, under low water stress condition, the free B content and semi-bound B content were higher than that of the optimum water treatments, which showed that B transportation and utilization in low B efficient cultivar was negatively affected because of low water soil stress condition2. Solution culture experiment results showed, boron and magnesium nutrition has a positive interaction on oil rape growth,in certain concentration range, other wise, they were synergistic. In optimum B condition, free and semi-bound B content of high B efficient cultivar were higher than that of low B efficient cultivar, and for low B efficient cultivar, bound B (localized in cell wall) was higher than that of high B efficient cultivar with lower free and semi-bound B content. Magnesium nutrition is beneficial to B transformation to the forms which easy to be transported, and B pool quantity was increased.Under optimum B condition, for high B efficient cultivar, more dry matter was built using little B for the high B efficient cultivar, but low B efficient cultivar need more B to complete life cycle. Under low B stress,...