Afield trial was conducted at the R&D Farm of Maharashtra State Grape Growers' Association, Pune, India to assess the performance of Thompson Seedless and its clones, namely Tas-A-Ganesh and Sonaka on Dog Ridge rootstock. Brix-yield the ultimate measure of productivity in grape, particularly in raisin grapes, was more in Sonaka compared to the rest, which were at par. Dominance of yield/vine over Brix content was evident in determining the brix yield. Vine yield was more in Sonaka compared to other varieties because of more number of clusters in spite of less bunch weight. Factors impairing shoot maturity namely, shoot length and rate of shoot growth were more; NO3-N status was more and K status less after back pruning in Sonaka. Fruitfulness of buds as indicated by the cluster/cane ratio was more resulting in more clusters/vine in Sonaka, though the canes/vine was less. Yield increase in Sonaka was mediated through more cane diameter, shoot length on the 45 th day and shoot growth rate during 30-45 days after back pruning; less number of shoots/vine and shoot length at veraison. Results of this trial revealed that Sonaka is the best variety on Dog Ridge for obtaining high yield of quality grapes and that the viticultural practices that increase the cane diameter, shoot length on the 45 th day and shoot growth rate during 30-45 days after back pruning; and reduce the number of shoots/vine and shoot length at veraison might help increase the yield in Thompson Seedless and Tas-A-Ganesh.

A survey was conducted to study the variation in nutrient absorption (petiole /Soil content) by Thompson Seedless grape as influenced by soil chemical characteristics on its own root, Dog Ridge and 110R rootstocks with an aim to provide guidelines in nutrient application with reference to the soil chemical characteristic and rootstock. Nutrient absorption was influenced most on own root followed by Dog Ridge and 110R roots. N followed by Zn, P and K were the most influenced nutrients on own root, while K, Mn and Zn on Dog Ridge; and Fe, N, K and Zn on 110R. All the soil chemical characteristics were ineffective in the absorption of Cu in vines on any root. Thompson Seedless root were more sensitive to soil pH in the absorption of P and S, and to CaCO3 levels in Ca absorption with a threshold level of 8.0 per cent. 110R root were independent of OC in N absorption, while Dog Ridge root exhibited dependence on OC for S absorption. Rootstocks in general, were more efficient in S beyond 1.5dSm-1. The ability to restrict the absorption of Na by rootstocks was dependent on the free calcium levels in the soil. 110R was most efficient in restricting the absorption of Na below 12.5 per cent, while Dog Ridge was equally efficient in the range of 12.5 -17.0 per cent. Variation in the efficiency in nutrient absorption with the rootstock at different levels of soil chemical characteristics was attributed to the specific ion contributing to the chemical character, its interaction with other nutrient ions, their relative abundance and the preferential absorption by the roots.Keywords Thompson seedless; Nutrient absorption; Rootstocks; Soil chemical; Characteristics IntroductionInfluence of soil physico-chemical characteristics on nutrient availability is well established (Truog, 1946;Russell, 1961). Absorption of a nutrient by a tree species depends not only on its availability, but also the relative contents of other nutrients (Emmert, 1959;Bergman et al., 1960), their ability to get adsorbed on to the root surface (Huffakar and Wallace, 1969;Wada and Weerasooriya, 1990), rootstock used (Smith and Wallace, 1956;Cook and Lider, 1964), affinity of the roots for nutrient ions (Asher and Ozanne, 1961;Downton, 1977) and nutrient interactions (Fageria, 2001;Wilkinson et al., 1999). Important chemical characteristics, which influence indirectly through their effects on nutrient availability and their interactions are, the organic carbon (Duxbury et al., 1989), pH (Sumner and Yamada, 2002), Electrical conductivity (Fisarakis et al., 2005), free calcium (Fageria, 2001) and exchangeable sodium percentage (Abrol et al., 1988). Rootstocks (Anna and Lajos, 2008;Antonio and Carlos, 2009;Marco et al., 2011) and the available nutrient status (Emmert, 1959;Bergman et al., 1960) were also shown to exert influence on the absorption of nutrients by grapevines. With this background, in a survey conducted in Thompson Seedless vines on their own roots and grafted on Dog Ridge and 110R rootstocks to study the variation, if any, in the absorp...

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