CHANGES OF PHOTOSYNTHESIS AND CHLOROPHYLL FLUORESCENCE UNDER HIGH TEMPERATURE STRESS IN COWPEA SEEDLING LEAVES

Two cowpea varieties (Vigna unguiculata W., ‘ZaoyouNo.1’ and ‘Youxuanzhijiang28–2’) were used to study the changes of photosynthesis and chlorophyll fluorescence under high temperature stress (45/33°C). The results showed that as time went by, all of the net photosynthetic rate (P_N), photochemical efficiency of photosystem (PS) 2 in the darkness (F_v/F_m) and quantum yield of PS 2 electron transport (ΦPS2) of the two varieties decreased.
Moreover, the stomata conductance (Gs) increased during the first three days, and then decreased.
However, the intercellular carbon dioxide (CO₂) concentration (Ci) increased.
These results indicated: 1. Under high temperature stress, non-stomatal limitation was the major factor leading to photosynthesis limitation. 2. The high temperature tolerance of ‘ZaoyouNo.1’ was demonstrably stronger than that of ‘Youxuanzhijiang 28–2’. 3. P_N, ΦPS II and F_v/F_m of the higher tolerance cowpea variety to high temperature were greater at 45°C/33°C (day/night) and 35°C/27°C (day/night). 4. When identifying high temperature tolerance of cowpea plants, P_N, ΦPS II and F_v/F_m can be used as physiological indexes.

XXVII International Horticultural Congress – IHC2006: International Symposium on Advances in Environmental Control, Automation and Cultivation Systems for Sustainable, High-Quality Crop Production under Protected Cultivation

Y. Li, X. Yu, Y. Liu, L. Yin

Vigna unguiculata W., photochemical efficiency of photosystem (PS) 2 in the darkness (F_v/F_m), quantum yield of PS 2 electron transport (ΦPS2), intercellular carbon dioxide concentration (Ci), net photosynthetic rate (P_N), stomata conductance (Gs)

https://doi.org/10.17660/ActaHortic.2007.761.34