Carbon isotope discrimination and water use efficiency of grape varieties, rootstocks and budded grapevines.

Abstract: Results are presented of 3 separate experiments conducted in Bangalore, Karnataka, India, during 2002-03 and 2003-04 to investigate the occurrence of variability in grape cultivars (Flame Seedless, Thompson Seedless, Sharad Seedless and Tas-A-Ganesh), rootstocks (Dog Ridge, 1613 C, Salt Creek, St. George and VC clone) and buddings in respect of physiological behaviour and carbon isotope discrimination (CID). There was genetic variability in water use efficiency (WUE) with respect to CID. The behaviour of genotypes differed significantly in CID before and after budding on different rootstocks. Dog Ridge rootstock was known to increase WUE of Flame Seedless and Sharad Seedless when CID and other physiological parameters were compared. However, Thompson Seedless increased its WUE when budded on Dog Ridge, which is confirmed by the least CID in this combination at 50% stress.