Growth and Development Characteristics of Winter Rapeseed Northern-Extended from the Cold and Arid Regions in China

Abstract

Nine cultivars of winter rapa with different cold-resistance were studied in the original growing regions and north extending regions. The results showed that the over-wintering rate of winter rapeseed reduced from 93.0%-100.0% to 40.0%-95.0%; The vegetative growth period before wilt leaf stage and the regreen stage to maturity was shortened greatly, while the duration from wilt leaf stage to regreen stage was longer than winter rapa planted in the original regions. The plant height and branch length were shortened, the 1000-grain weight and the seeds in each lique were higher at Zhangye than at Tianshui. The ultra winter-hardy cultivars and the reasonable growing date and density should be adopted in order to increase the over-winter rate of winter rapeseed in winter rapeseed extending northern regions.

Identification of cold stress responsive microRNAs in two winter turnip rape (Brassica rapa L.) by high throughput sequencing

“…Under cold stress, the MDA content in leaves and POD activity in roots of ‘Longyou 7’ were higher than ‘Tianyou 4’, indicating cold stress led to more serious membrane damage in leaves of ‘Longyou 7’, but cold tolerance of ‘Longyou 7’ roots was stronger than ‘Tianyou 4’ under cold stress. These physiological changes under cold stress agreed to the previous reports [ 28 , 58 ].…”

“…Cold stress triggered 10 differentially expressed miRNAs in the leaves of ‘Longyou 7’, but only one miRNA was up-regulated in the roots of ‘Longyou 7’. As previously reported, root tolerance to cold is very important for survival of ‘Longyou 7’ in winter [ 28 ]. Thus, we suspect the differentially expressed miRNA induced in roots of ‘Longyou 7’ might be valuable to its better survival rates compared with ‘Tianyou 4’.…”

“…Thus, we suspect the differentially expressed miRNA induced in roots of ‘Longyou 7’ might be valuable to its better survival rates compared with ‘Tianyou 4’. The aboveground part of ‘Longyou 7’ becomes more sensitive to cold stress, exhibiting poor growth and senescence [ 28 ]. Therefore, the number of differentially expressed miRNAs in the leaves of ‘Longyou 7’ was higher, which might be related to the solutions of ‘Longyou 7’ to alleviate cold induced injuries such as cytoplasmic damages caused by ice [ 55 ].…”

“…Winter turnip rape ( B. rapa L.) is a valuable oil crop for its high-quality edible oil in northwestern China, which is also capable of conserving soil and water in winter and spring [ 28 ]. However, extremely low temperature negatively affects the growth and development of winter turnip rape, which consequently fails to overwinter and propagate in northwestern China.…”

“…And ‘Tianyou 4’ is a cold-sensitive winter turnip rape variety. Recently, our group has investigated the physiological, biochemical, and molecular mechanisms of cold-tolerance in winter turnip rape [ 28 – 31 ]. Whereas the miRNAs and target genes with putative functions in cold tolerance of B. rapa has not been reported yet.…”