EFFECT OF COLD HARDENING ON SOME PHOTOSYNTHETIC CHARACTERISTICS OF PEA (Pisum sativum L., CV. RAN 1) PLANTS

The effect of 96 h cold acclimation of pea (Pisum sativum L., cv. Ran 1) plants on their photosynthetic capacity was investigated. It was found that pea plants were able to modulate their photosynthetic rate during growth at low temperature and adjust it to needs for survival. The advantages of hardening to low temperature were very clearly expressed when the effects on O2 evolution and on the relative part of QB non-reducing centres were analysed. Analysis of photosynthetic rates and fluorescence parameters showed that these processes were more resistant to freezing in cold hardened than in non-hardened pea plants. It was proposed that for pea plants the maintenance of active photosynthesis at low overzero temperatures is also very important for survival, because in early spring such unfavourable conditions are not rare.