The Influence of Water and Gas Exchange Parameters on Grafted Grapevines Under Conditions of Moisture Stress

Among the four grape varieties that were subjected to moisture stress, Flame Seedless and Thompson Seedlessrecorded the highest relative water content, osmotic potential and water potential compared to Sharad Seedless andTas-A-Ganesh. Similarly, Flame Seedless and Thompson Seedless recorded the maximum rate of photosynthesis,the minimum transpiration rate, and thus increased water-use efficiency. Sharad Seedless on its own root had thelowest water-use efficiency. Budding the respective four varieties on different rootstocks and subjecting them tomoisture stress resulted in significant differences in various physiological parameters that influence water-use efficiency.When Sharad Seedless was budded on Dog Ridge rootstock and subjected to moisture stress, it resulted inincreased water potential, osmotic potential and water use efficiency compared to other rootstocks. This suggeststhat rootstocks have an influence on the physiological mechanisms of scion leaves. Hence, the genotypic selection ofrootstocks for establishing vineyards under drought conditions is of great importanc

Effect of Leaf Removal on Composition of Wine Grape Varieties Grown in Semiarid Tropical Climate of India

Removing leaves from cluster zone is one of the management practices followed to improve fruit composition in temperate wine grape growing countries. However, knowledge on canopy management practices to improve fruit and juice composition for quality wine making is still lacking in semiarid tropical regions of India. Due to ample sunlight availability during fruit growth in semiarid tropics, it is unclear whether the leaves have to be removed from cluster zone. In case the leaves have to be removed, the direction from which it has to be done is also important. Hence, this study was conducted to see the effect of leaf removal from two sides of canopy on fruit composition in two wine grape varieties. In Cabernet Sauvignon vines leaf removal from both east and west side of the canopyimproved fruit quality in terms of reduced pH, potassium, malic acid and increased phenolics. Nevertheless, removing leaves from eastern side was found to be better than western side, because clusters are exposed toexcess sunlight. However, in Sauvignon Blanc, leaf removal from east side improved most of the desirable fruit composition parameters, while leaf removal from west side reduced the fruit quality in terms of sugars, acids, pH, total phenols etc

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Not AvailableIn the present study on growth and yield of grapes cv. Sharad Seedless different sources and methods of potassium were applied. The experiment was laid out with eight treatments replicated four times in Completely Randomized Block Design at the ICAR-Indian Institute of Horticultural Research, Bengaluru in 2016-17. Three different sources of potassium fertilizers viz., sulphate of potash (SOP), potassium nitrate (KNO3) and 19: 19: 19 and two methods of application viz., soil application and fertigation were applied to Grape vines. Among the treatments, highest mean pruned biomass (1.47 kg vine-1) and yield vine-1 (7.42 kg) were recorded in vines treated with 40% KNO3 through fertigation + 60% SOP through soil and lowest yield vine-1 (5.21 kg) was observed in vines treated with 100% SOP through fertigation. Vines, which received 60% KNO3 through fertigation + 40% SOP through soil, had recorded maximum percent of fruitful canes vine-1 (51.31).Not Availabl

Changes in Polyphenol Oxidase Activity During Rooting of Hardwood Cuttings in Three Grape Rootstocks Under Indian Conditions

Polyphenol oxidase (PPO) activity was investigated during rooting in cuttings from the rootstocks Dog ridge, 110 Rand St. George, belonging to different Vitis species. Enzyme activity and rooting ability were analysed. Significantdifferences were found in PPO activity among different rootstocks, with Dog ridge and 110 R having the highest PPOactivity during the initial period of planting, followed by a decrease in enzyme activity. In St. George, the enzymeactivity was least during the initial periods, but it increased throughout the experiment. The initiation of rootingprimordia was observed until 60 to 90 days after planting in Dog ridge and 110 R rootstocks, while it was observed120 days after planting in St. George, suggesting differences in the rooting behaviour of the rootstocks. The statusof various biochemical components of the mother vines, such as total phenols, reducing sugars, carbohydrates,nitrogen, C:N ratio, etc. were analysed to investigate the influence of these constituents on the rooting ability of therootstocks apart from PPO activity

Potassium fertilization in relation to downy mildew disease incidence in grape leaves

Influence of different sources of potassium and their method of application was studied on incidence of downy mildew infection in grape leaves of 'Sharad Seedless' (syn: 'Kishmish Chorni'). The total phenolic content and individual phenolic acids were analysed from healthy and downy mildew infected leaves of 'Sharad Seedless' and the degree of downy mildew infection was well correlated with potassium content in the petioles. Different sources and method of potassium application had significant effect on Phenylalanine ammonia-lyase (PAL) enzyme activity and preformed phenols in healthy vines. Significant increase in PAL enzyme activity, total phenols and individual phenolic acids was registered with increase in disease severity. Magnitude of percent change in PAL enzyme activity and total phenolic content was highest in vines with maximum disease infection. Among the phenolic acids, o-Coumaric acid, p-Coumaric acid have a definite role in disease resistance. We could also observe the variation in disease severity in vines which received different sources of potassium which was supplied in different quantities whether through soil and/or through fertigation

Physiological and Biochemical Characterisation of Grape Rootstocks

Ten grape rootstocks were characterised for their various morphological, physiological and biochemical parameters.Significant differences were observed for most of the parameters studied. Rootstocks in the group of Vitis berlandierii× Vitis rupestris, such as 110 R, 1103 P, 99 R and B2-56, had a significantly higher content of total phenols, flavon-3-ols, flaveonoids, proline and total protein. Optimum C/N ratios in the mother vines of these rootstocks helped attainbetter rooting percentages of hardwood cuttings. Rootstocks such as Dog Ridge, 110 R, B2-56 and Salt Creek recordedthe highest relative water content (RWC) and water-use efficiency (WUE) at single-leaf level, which is an importantmechanism in overcoming drought tolerance. The high phenolic content in rootstocks such as Dog Ridge, 99 R, 110Rand 1103 P may help in reducing the incidence of major grape diseases in commercial table varieties if grafted ontothese rootstocks. This was established in our earlier studies of the incidence of powdery mildew in Thompson Seedlessgrafted onto different rootstocks. A significant and positive correlation was observed for WUE and total proteinand proline content. Thus, the physio-biochemical characterisation of rootstocks may help to identify particularrootstocks that could influence a desired trait in commercial table / wine grape varieties after grafting

Berry Weight, Quality and Cane Biochemistry Changes in Relation to Cane Thickness of Own-Rooted and Grafted 'Tas-A-Ganesh' Grape

A field trial was conducted to determine the effect of cane thickness on berry quality and other biochemical parameters in 'Tas-A-Ganesh' grape at National Research Centre for Grapes, Pune, during the year 2008- 2009. Average bunch weight increased with increase in cane diameter. Own-rooted vines of cane thickness <6mm sprouted earlier than thicker canes. TSS of berries decreased with increase in berry size. Berries on grafted vines recorded lower TSS than on own-rooted vines. Biochemical parameters such as content of reducing sugars, carbohydrat and phenols were higher in grafted vines of cane thickness >10mm. Results indicate that thicker canes either on their own roots or on grafted vines are superior for yield and yield components, as also for physical properties of bunches and berries and total carbohydrate content of the canes

Influence of Rootstocks on Growth Yield and Fruit Composition of Thompson Seedless Grapes Grown in the Pune Region of India

The use of rootstocks is gaining importance in Indian viticulture due to problems associated with abiotic stresses,such as drought and salinity, and also to improve scion characteristics. Thompson Seedless is the only commercialcultivar grown for both fresh consumption and raisin making. Dog Ridge was the only popular rootstock usedby grape growers prior to late 1990s. But this rootstock was known to induce more vigour in scions, resulting inreduced bud fruitfulness and thereby fruit yield. To identify alternate rootstocks suitable for Thompson Seedless, astudy was initiated in the National Research Centre for Grapes, Pune, India during the year 2001. Five rootstockswith own rooted vines were evaluated in this study. During the initial years, Thompson Seedless grafted on DogRidge produced the highest yield, with good quality fruit. Over the years we could observe uneven bud sprouting,gaps on the cordon due to dead wood formation, and reduced yield in vines grafted on Dog Ridge rootstocks. Incontrast, Thompson Seedless grafted on 110R performed well in terms of moderate vigour, increased fruitfulnessand consistently higher yield. Dog Ridge and St. George produced a lower yield, owing to increased vigour measuredin terms of pruning weight, total shoot length and cane diameter. Rootstocks 110R, 1103P and 99R are also known toincrease water-use efficiency during critical growth stages of fruit bud differentiation and full bloom. No significantinfluence of rootstocks was observed for most of the fruit composition parameters. Larger and bolder berries wereproduced on Dog ridge and 110R rootstock, while they were the smallest on own rooted vines

Effect of Soil Moisture Stress on Physiological Response in Grape (Vitis vinifera L.) Varieties

Four varieties of grape namely Flame Seedless, Thompson Seedless, Sharad Seedless and Tas-A-Ganesh were subjected to different levels of moisture stress to study their physiological response. Stress was imposed for 14 days by withholding irrigation. Observations on relative water content, leaf water potential, leaf osmotic potential and gas exchange parameters like photosynthetic rate, transpiration rate, stomatal conductance and water use efficiency (WUE) were recorded. None of the varieties could survive for 14 days without irrigation (100% stress). Flame Seedless and Thompson Seedless at 50% moisture stress maintained higher turgidity as indicated by lesser reduction in relative water content and water potential attributed to better osmotic adjustment. Marginal reduction in photosynthesis and greater reduction in transpiration rate in the variety Flame Seedless may have resulted in higher WUE under moisture stress. Higher photosynthetic rate, lower transpiration rate, higher water relation parameters and high WUE in Flame Seedless under soil moisture stress indicated its better tolerance to drought

Advancing fruiting season in Annona cv. Arka Sahan through pruning

Annona cultivar ‘Arka Sahan’, an inter-specific hybrid of Annona atemoya × A. squamosacomes to harvest during August-September under mild tropical climate, which coincides with monsoon rains resulting in poor fruit quality and high susceptibility to anthracnose and fruit fly. An attempt was made to advance the fruiting in this hybrid through pruning during 2016- 17 and 2017-18. The effect of three pruning levels (25, 50 and 75% of previous season’s growth) at five different times (60, 75, 90, 105 and 120 days after final harvest of previous crop) on flowering and fruiting were compared. Early sprouting, flowering and fruit harvest were recorded in trees pruned to 75% of the past season’s growth in both the years. Earliest fruits were harvested 271 (3rd week of June) and 268 (2nd week of June) days after pruning in trees pruned during first week of October in 2016-17 and 2017-18 respectively (P<0.05).Bigger fruits with lesser seeds per 100 g of pulp (P<0.05) were harvested from trees pruned to 75% and 25% levels in the first and second year, respectively, irrespective of pruning time. Tree canopy following pruning at 75%level recorded higher light interception and photosynthetic rate (P<0.05). Pruning time and levels significantly influenced the biochemical constituents of leaf and shoot. The fruiting in cultivar ‘Arka Sahan’ could be thus advanced by 8-9 weeks to June from the normal season of August-September with comparable or better fruit quality by pruning 75% of the last season’s growth during October