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Physiological Effects of Winter Rape ( Brassica napus var. oleifera ) Prehardening to Frost. I. Frost Resistance and Photosynthesis during Cold Acclimation
Author(s) -
Rapacz M.,
Janowiak F.
Publication year - 1998
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.1998.tb00392.x
Subject(s) - photosynthesis , frost (temperature) , cold hardening , biology , acclimatization , brassica , agronomy , horticulture , hardening (computing) , botany , chemistry , organic chemistry , layer (electronics) , geomorphology , geology
The objective of the research was to define the changes in photosynthetic activity induced by prehardening and to determine their involvement in frost tolerance of winter rape. Prehardening of winter rape, consisting of keeping the plants at + 12°C during the light periods from sprouting until the beginning of the 1st stage of cold hardening, contributed to increasing its effectiveness. After 42 days of hardening at + 2°C the resistance of the prehardened plants equalled that attained by winter rape in the most favourable seasons of vegetation in the field. Prehardening stimulated the efficiency of photosynthesis at chill temperatures (+ 2–5°C). Differences in photosynthetic efficiency, like those in frost resistance, increase with successive weeks of hardening. They also concern the leaves already developed at the hardening temperature. A prehardened photosynthetic apparatus is less susceptible to the progress of photoinactivation taking place when the seedlings are kept at + 2°C. It also demonstrated greater activity even during the first hour of hardening or in the newly expanding leaves, and also at higher temperatures, most probably because of the more efficient progress of the dark, processes. The described changes in the functioning of the photosynthetic apparatus induced by prehardening were thus qualitatively very similar to those observed during long‐term growth at + 5°C. already described in the literature.