Growth, chlorophyll content, photosynthesis and water relations in guava (Psidium guajava L.) under salinity and different nitrogen supply.

摘要

The effects of NaCl (30 mM) in combination with N (5, 10 or 15 mM Ca(NO3)2) on growth and physiology of 2 Sudanese guava cultivars (Pakistani with white fruit pulp and Ganib with red pulp) were investigated. Salinity reduced shoot growth and leaf chlorophyll content, but these parameters were improved by a moderate N supply. Salinity reduced net photosynthesis rate (PN) and transpiration (T), but a moderate N supply enhanced PN and T. Stomatal resistance (Rs) was high under saline conditions, whereas it was comparatively low for trees moderately supplied with N. The salinity-induced decrease in PN of red guava was attributed to stomatal closure. In white guava this was due to non-stomatal factors. Xylem flow rates were similar for both cultivars and for all treatments except those supplied with NaCl alone, but the highest flow rates were observed under moderate N supply. It was concluded that red guava is more salt tolerant than white guava.