The Effects of Drought Stress on the Photosynthetic Parameters and Dry Leaf Yield of <i>Stevia rebaudina</i> Bertoni

Abstract

The effects of drought stress on the photosynthesis and dry leaf yield in the different Stevia rebaudina Bertoni germplasms of: IS-1, QF-1, QTZ4, JD-1 and AL-4 was studied with the pot method in greenhouse. The results indicated that the net photosynthetic (Pn), transpiration rate (Tr) and dry leaf production of stevia showed different degree changes with the continuing of drought-stress time. There was no significant change in Pn, Tr and dry leaf production in short-term drought-stress treatment(Ta:5d), but as the time of drought-stress continuing, the Pn were on the declining trend: the Pn of various materials in T2 (without irrigation for 10d) showed maximum decrease, they decreased for 28.85%, 47.04%, 43.03%, 43.61% and 42.25% than that in T1 (without irrigation for 5d), respectively. The variation trend of Tr in various materials were the same to the Pn. And it indicated that there was no appreciable impact on the dry leaf yield in the mild drought (without water for 5d), but with the drought stress continuing, the dry leaf yield of per plant became less and less. The varying degrees decreases of dry leaf yield in different materials with the same drought stress showed that different materials with different tolerance to drought stress.