Comparative Studies of Net Photosynthesis and Transpiration of Some Citrus Species and Relatives

Abstract

AbstractComparisqns were made between ‘Campbell Valencia’ orange (Citrus sinensis (L.) Osbeck), and ‘Gabon Cherry‐orange’ (Citropsis gabunensis (Engl.) Swing.), ‘Frost Lisbon’ lemon (Citrus limon (L.) Burm. f.) and ‘Eremolemon’ (Eremocitrus glauca (Lindl.) Swing. ×Citrus limon (L.) Burm. f.) and between diploid and autotetraploid ‘Lisbon’ lemons with respect to the influences of temperature and humidity on net photosynthesis and transpiration.Net photosynthesis, leaf conductance to water vapor and water‐use‐efficiency of Citropsis gabunensis were lower than with Citrus sinensis.‘Eremolemon’ had higher net photosynthesis and higher water‐use‐efficiency than ‘Lisbon’ lemon, but only small differences were observed between the two species in leaf conductance to water vapor. Small, nonsignificant, differences were observed between diploid and tetraploid ‘Lisbon’ lemons in responses of net photosynthesis and leaf conductance to temperature and humidity. Temperatures above 30°C and increases in vapor pressure difference caused declines in net photosynthesis and increases in vapor pressure difference resulted in decreases in leaf conductance to water vapor by all of the species used in these studies.