Effect of acclimation duration and sucrose level on the cold tolerance of Brassica napus L

Pagrindinis veiksnys, lemiantis žieminiu rapsu (Brassica napus L.) derlinguma Lietuvoje, yra atsparumas žemai temperaturai, kuris gali buti padidinamas grudinimo metu. Tirta endogeniniu ir egzogeniniu veiksniu itaka žieminiu rapsu daigu šalcio atsparumui in vitro. Maitinamojoje terp je su skirtinga sacharoz s koncentracija tirtos aštuonios žieminiu rapsu veisl s esant trims grudinimo režimams bei trims šaldymo temperaturoms. Dvieju savaiciu amžiaus daigai grudinti 14, 28 ir 42 dienas +4 ºC temperaturoje. Augalai šaldyti -7, -9 ir -11°C temperaturoje 24 valandas, o po to auginti 30 dienu auginimo kameroje. Ivertinus po šaldymo išlikusiu daigu kieki procentais nustatyta, kad kiekvieno genotipo optimali grudinimo trukm yra savita. Tirtas biometriniu parametru kitimas skirtingu atsparumu šalciui pasižyminciose rapsu veisl se (‘Valesca’ ir ‘Silvia’) in vitro. Didinant sacharoz s koncentracija maitinamojoje terp je rapsu daigu atsparumas šalciui didėjoA major factor affecting winter rapeseed (Brassica napus L.) production in Lithuania is winter-hardiness or cold tolerance, which can be enhanced by cold acclimation. The effect of endogenous and exogenous factors on cold tolerance of winter rapeseed seedling in vitro was investigated. Experiment was comprised of three acclimation terms, three freezing temperatures, eight winter rapeseed cultivars, and four concentrations of sucrose in medium. Seedling growth stage of 2 weeks was acclimated in a vernalization chamber at +4°C for 14, 28 and 42 days. The plants were then placed in a programmable freezing chamber at +2 °C and temperature decreased/increased 1°C h-1 to and from a minimum temperature. The freezing temperature was -7, -9, and -11°C, duration of the freezing temperature was 24h. After freezing the seedlings were transferred to a growth chamber for 30 days. The percentage of seedling survival was determined for each treatment. It was established that the optimal acclimation duration and cold resistance of winter rapeseed seedling in vitro is strongly genotype dependent. The change of biometrical parameters of growing in vitro seedlings were examined using two rapeseed cultivars (‘Valesca’ and ‘Silvia’) differing in cold tolerance. The increasing levels of sucrose in culture medium caused significant increase in cold resistance of rapeseed seedlingsVytauto Didžiojo universitetasŽemės ūkio akademij