GAS EXCHANGE CAPACITY OF CROATIAN COMMON BEAN LANDRACES (PHASEOLUS VULGARIS L.) IS RELATED TO THEIR ORIGIN AND GROWTH TYPE

The long tradition of common bean (Phaseolus vulgaris L.) cultivation in Croatia has resulted in the development of many landraces, which create a valuable basis for screening different physiological traits. Studying gas exchange parameters could provide valuable information that could be useful in creating new crop germplasm with enhanced agronomic attributes. Variability of gas exchange parameters, such as the net photosynthetic rate (A), transpiration rate (E), stomatal conductance (g(s)), intercellular CO2 concentration (C-i), light use efficiency (LUE), and water use efficiency (WUE) were studied on the collection of 226 common bean accessions and the relationship of the gas exchange parameters with the origin and morphological traits was tested. The highest variability among all landraces was found for the WUE and g(s), and lowest for the A and LUE traits, indicating high potential of these traits to be used for selection and breeding programs. Accessions of the Mesoamerican origin had higher A and LUE and lower C-i values compared to accessions of the Andean origin. Accessions with the determinate growth had higher gs and C-i values and lower A, LUE and WUE values compared to accessions with the indeterminate growth. The variance components analysis showed that the growth type has a more pronounced effect on g(s), C-i and WUE, whereas the origin has a stronger impact on A and LUE. The principal component analysis (PCA) showed that A separates accessions according to their origin, whereas C-i separates accessions according to their growth type. Accessions with higher C-i had lower A, indicating possibly higher rates of carboxylation per active site on the enzyme and/or higher regeneration capacity of Ribulose-1,5-bisphosphate (RuPB) in the Calvin cycle in accession with high A.