Photosynthetic performance of grape varieties in the tropical climate of India

Photosynthetic characteristics are critical indicators of a plant’s ability to grow and achieve high yield under specific climatic conditions. In this study, grape varieties including ‘Thompson Seedless’, ‘Bangalore Blue’, ‘Red Globe’, and ‘Crimson Seedless’, along with newly released varieties ‘Manjari Medika’, ‘Manjari Kishmish’, and ‘Manjari Shyama’ were evaluated for their photosynthetic performance under tropical climatic regions of India. The results showed a significant positive correlation of yield and biomass with parameters such as apparent quantum yield, net photosyn­thetic rate, chlorophyll content, and leaf area index (LAI). This indicates that varieties exhibiting higher photosynthetic efficiency also produced greater biomass and yield. Hierar­chical clustering grouped the seven varieties into three dis­tinct categories. ‘Manjari Medika’ and ‘Red Globe’ formed the first category due to their superior apparent quantum yield, net photosynthetic rate, chlorophyll content, and LAI, resulting in the highest yield and biomass. The second category included ‘Manjari Kishmish’, ‘Manjari Shyama’, and ‘Thompson Seedless’, while ‘Crimson Seedless’ and ‘Bangalore Blue’ were grouped in the third category, having comparatively lower photosynthetic performance. Princi­pal Component Analysis (PCA) and a comprehensive eval­uation using the TOPSIS method ranked the varieties based on their photosynthetic traits. ‘Manjari Medika’ and ‘Red Globe’ ranked the highest, whereas ‘Bangalore Blue’ ranked the lowest. Overall, the findings highlight that in the tropical climate, ‘Manjari Medika’ and ‘Red Globe’ exhibit superior photosynthetic performance and yield potential, followed by ‘Manjari Kishmish’, ‘Manjari Shyama’, and ‘Thompson Seedless’.