CO2 assimilation and transpiration balance in species of genus Vitis cultivated in vivo and in vitro. Estimation of stomatal and cuticular transpiration in vitro

Abstract

The influence of genotype on leaf gas exchange was investigated for Vitis riparia and Vitis rupestris plants cultured in vivo and in vitro. Gas exchange was measured at constant temperature and photosynthetic photon flux density and at varying relative humidity from 75 p. cent to 65 p. cent.

Differences of transpiration and CO₂ assimilation rates between genotypes were observed that did not depend upon conditions. Water use efficiency was strongly controlled by the genotype.

Linear correlations between assimilation, transpiration and relative humidity were used to estimate extra stomatal (cuticular) and stomatal transpiration of in vitro plants. Cuticular transpiration of in vitro plants was also measured directly during the darkness. Our results confirmed the indirect estimates of cuticular transpiration elaborated with a linear regression model. Results also show that cuticular transpiration of in vitro grown plants may be relevant and is strongly influenced by the genotype. Similarly, the sensitivity of plantlets to transplantation from in vitro to in vivo conditions may be strongly related by the genotype.