A NEW ADAPTED METHOD FOR SCREENING PHASEOLUS GENOTYPES FOR TOLERANCE TO LOW TEMPERATURE

The selection and characterization of 620 bean forms, from the genbank- Sadovo- Bulgaria, from ssp. volubillis ssp. nanus was achieved. The studied genotypes are from Europe, North and South America, Africa Asia. The study aimed to indicate the cool tolerant forms by using a new and original screening method. The photosynthetic intensity/through 14 CO2 /the activity of catalaze /gasometerically/ and peroxidase /colorimetricaly/ and the plastid pigment contents/ spectrophotometrically, of different genotypes snap bean with varied cool tolerance was studied. The genotypes which studied have widely differed in the peroxidase activity. The genotypes with highest cool tolerance are characterized with lower peroxidase activity, while the genotypes with moderate tolerance genotypes are characterized with increased enzyme activity- 588, 667, 845 E60s/g respectively. With the genotypes which have higher cool tolerance there is a tendency toward to increased plastid contents and catalase activity, but the differences are not so significant. The conclusion is that the peroxidase can be used as cool tolerance criterion.