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.
Variation in the relationship among cane and cluster characteristics in Thompson Seedless and its mutants, Tas-A-Ganesh and 2A, was assessed with an aim to (a) identify the basis for variations, (b) determine the optimum levels of the attributes of yield and quality, and (c) suggest the means to improve the desired attributes in the three clones of grapes. Variation in the number of clusters/cane, the number of berries, rachis length and brix yield per cluster was highest in 2A, while the brix yield/cane was highest in Thompson Seedless. Pearson correlation coefficients indicated significant variations between the clones in respect of cane diameter, buds broken/cane, brix yield/cluster, clusters/cane, berries/cluster, berry diameter and rachis length/cluster. Multiple linear regression equations involving cane diameter, buds broken/cane, clusters/cane, rachis length/cluster, berries/cluster, berry diameter and cluster compactness could explain the variation in brix yield/cluster to be 69.0, 71.4 and 44.1%, in Thompson Seedless, Tas-A-Ganesh and 2A clones respectively. Cluster compactness had more contribution towards brix yield/cluster in 2A, while cane diameter and the number of broken buds/cane contributed more in Tas-A-Ganesh. Cluster compactness in turn was determined to be 94.9, 80.5 and 32.6%, in Thompson Seedless, Tas-A-Ganesh and clones respectively, by cane diameter, uniformity in bud break, uniformity in flowering rachis length (cm)/cluster, berries/cluster, berry diameter (mm) and clusters/cane together in a multiple regression analysis. These investigations revealed the scope to increase the brix yield/cluster in Thompson Seedless by increasing the total rachis length and retain a larger number of berries/cluster; increase the fruitfulness of buds and removal of unfruitful shoots after forward pruning to increase the brix yield/cane in Tas-A-Ganesh and to elongate the clusters and reduce the number of berries to produce loose to well-filled clusters; and increase the berry diameter in 2A.
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...
In view of the stage specificity for the efficacy of blanket sprays of GA3 for berry thinning, a field trial was laid out to achieve uniform flowering in Tas-A-Ganesh grapevines subjected to chemical defoliation prior to and hydrogen cyanamide application at fruit pruning in the double pruning and single cropping system during 2013-14 and 2014-15 fruiting seasons in growers’ vineyards around Nashik, Maharashtra by removing the un-uniformly thick canes. GA3 at different doses was sprayed two or three times to address the variation in uniform flowering, if any in cluster elongation and reducing the berry number/cluster. Cane regulation and GA3 sprays were used to achieve uniformity in bud break and flowering. Cluster compactness was derived by multiplying the number of berries/ cm length of rachis with berry diameter. Regression analysis of the variation has revealed that the cane diameter, through uniformity in bud break, influenced the uniformity in flowering which in turn influenced the cluster compactness through increased efficacy of blanket GA3 sprays in reducing the berry number/ cluster. Based on the optimum values of the contributory factors to cluster compactness, cane removal coupled with two blanket sprays of GA3 @ 30 g a.i./ha or retention of all canes coupled with three blanket sprays of GA3 @ 20 g a.i./ha was found to be ideal to obtain loose to well filled clusters. Taking together into account the effect of treatments on cluster compactness, yield and quality, retention of all canes coupled with three sprays of GA3 @ 20 g a.i./ha was considered appropriate for table grape production in Tas-A-Ganesh cv. of grapes.
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