Preparation of oilseed rape for over-wintering according to autumnal growth and cold acclimation period.

A field experiment on different sowing dates of the two winter rape cultivars ‘Sunday’ and ‘Kronos’ (hybrid) was carried out during 2008–2009 at the Experimental Station of the Lithuanian University of Agriculture (54°53′N + 23°50′E). The soluble protein assays were done at the Laboratory of Plant Physiology, Institute of Botany. The study was designed to explore the effect of autumnal growth and cold acclimation period on winter rape (Brassica napus L.) cultivars’ preparation for over-wintering. According to biometric parameters (number of leaves per plant, root collar diameter and height of apical bud), rape sown in the second half of August (20 08) and at the end of August (30 08), whose autumnal growth and cold acclimation period was 64–76 days, was best prepared for wintering. The duration of autumnal growth and cold acclimation period significantly influenced biometric parameters of both winter rape cultivars. A consistent increase in the amount of crude protein in apical bud of both winter rape cultivars of later sowing dates was estimated. Upon completion of cold acclimation (preparation for wintering) period, the composition of soluble protein fractions derived from the cells significant for rape wintering organs – apical buds – was analyzed. The differences or/and peculiarities in protein composition in these cells of both tested cultivars ‘Kronos’ and ‘Sunday’ as influenced by the duration of their autumnal growth and cold acclimation period were revealed. It was established that a higher content of individual protein components and proteins having molecular masses less than 66 kDa were accumulated in ‘Kronos’ apical bud cells. A longer autumnal growth and cold acclimation period had a more distinct effect on the increment of protein component number in ‘Kronos’ compared to cv. ‘Sunday’, while a shorter (about 60 days) period exerted a negative effect on the total soluble protein component number in apical buds of both tested cultivars, especially ‘Kronos’.