Utilisation of Nitrogen by the Grape-vine as Affected by Time of Application and Soil Type

Two-year-old Chenin blanc vines in sand culture were nurtured with 15N-labeUed nutrient solution at three different phenological stages, i.e. (1) between end of bloom and end of rapid shoot growth (spring), (2) between the end of rapid shoot growth and veraison (summer) and (3) post-harvest (autumn). The fate of the applied 15N was followed quantitatively over one year. In the spring and summer treatments, 43% of the labelled N was translocated to the bunches while only 22 % was still present as N reserves at the start of the next season. In the autumn treatment, however, 68 % of the labelled N was still present as reserves at the start of the next season. For the spring and summer treatments, migration of N from the leaves prior to leaf-fall and from the shoots prior to pruning, accounted for about 60% of the N reserves present at the start of the next season. Labelled N was also applied in the field during spring and autumn, using vines on sandy loam (20% clay) and sandy (8% clay) soils as test material. In the sandy loam soil about 30% of the labelled N from both the spring and autumn treatments was utilised by the vine up to the end of bloom in the following season. In the sandy soil about 50% of the labelled N was utilised by the vine during the same period. It is suggested that the higher utilisation of N on the sandy soil could be due to a lower content of organic matter. Less mineral N in the root zone of the sandy soil may cause a smaller dilution of applied N, giving rise to a larger fraction ofapplied N being utilised

Effects of Soil Parent Material and Climate on the Performance of Vitis vinifera L. cvs. Sauvignon blanc and Cabernet Sauvignon - Part I. Soil Analysis, Soil Water Status, Root System Characteristics, Leaf Water Potential, Cane Mass and Yield

In the Helderberg area of the Western Cape, South Africa, soil parent material may vary between graniteand shale over relatively short distances. However, little information is available concerning the possibleeffects of different soil parent materials on grapevine performance. A five-year investigation (2004/05 to2008/09) was therefore carried out. Two Sauvignon blanc and two Cabernet Sauvignon vineyard blockswere selected at four localities. Soils derived mainly from granite and shale were identified in each vineyardblock. Climate and soil parameters, root distribution, grapevine water status, cane mass and yield wereevaluated at all localities. Shale-derived soils contained significantly greater amounts of fine sand, butless coarse sand, than granite-derived soils. These differences resulted in water-holding capacities thatwere generally higher in the shale-derived soils. Shale-derived soils contained higher concentrations oftotal potassium (K), but the levels of water-soluble K were generally greater in the granitic soils. Rootsystem development could not be related directly to soil parent material. However, in most cases fine rootdensity in the granite-derived soils tended to be higher, while the cane mass and yield of grapevines in thesame soils also tended to be higher, at least at two of the four localities. The effect of soil parent materialon grapevine water constraints seemed more prominent during the drier seasons, namely 2004/05 and2005/06, compared to the wet and coolest seasons, 2007/08 and 2008/09

Effects of Soil Parent Material and Climate on the Performance of Vitis vinifera L. cvs. Sauvignon blanc and Cabernet Sauvignon - Part II. Climate, Leaf Analysis, Juice Analysis and Wine Quality

A five-year investigation (2004/05 to 2008/09) was carried out in two Sauvignon blanc and two CabernetSauvignon vineyards in the Helderberg area, Western Cape, South Africa. Soils, derived mainly fromgranite and shale, were identified in each vineyard. Climatic parameters were measured, while leaves andjuice were analysed. Experimental wines were prepared and evaluated annually. The nutritional statusof the leaf blades and petioles was not affected by soil parent materials in a consistent pattern. Juice N ofgrapevines on the shale-derived soil was usually higher than that of vines on the granite-derived soil. Theeffect of soil parent material on Sauvignon blanc wine style appeared to have been more distinct at thelocality where wine quality was highest. At this locality, wine from the grapevines on shale-derived soil(higher water-holding capacity) was best in 2004/05 (dry season), while the reverse was true in the 2007/08season (wet). The style and/or quality of Cabernet Sauvignon wines were affected to a greater extent bydifferences in soil parent materials, relative to Sauvignon blanc. Differences were especially noticeableduring the cooler and wetter seasons. Better drainage in the case of the granite-derived soils, due to thehigher coarse sand fraction, may have played a positive role during these seasons

The distribution of the ratios of characteristics roots (condition numbers) and their applications in principal component or ridge regression

AbstractIn regression analysis large condition numbers indicate the presence of multicollinearity. Principal component regression and ridge regression are used to correct for the ill effects of such collinearities. In this paper some distributional properties of the condition number are considered

Comparison of Three Different Fertigation Strategies for Drip Irrigated Table Grapes – Part II. Soil and Grapevine Nutrient Status

A field trial was carried out in a drip irrigated Dan-ben-Hannah/Ramsey table grape vineyard near Paarlin the Berg River Valley region of South Africa to compare three fertigation strategies. Fertilisers wereapplied (i) two weeks after bud break, fruit set and post-harvest (LF), (ii) weekly from two weeks afterbud break until ten weeks after harvest, except during berry ripening (WF), and (iii) in daily fertigationpulses (DF). Grapevines of all treatments received c. 116 kg/ha N, 22 kg/ha P and 92 kg/ha K per season.Grapevines of all the fertigation strategies were thinned to obtain a normal and high crop load, whichis 26 and 36 bunches per grapevine respectively for Dan-ben-Hannah under the given conditions. In thecase of DF, the soil directly beneath the drippers became acidic after three years. Salt also accumulated onthe perimeter of the wetted soil volumes. Petiole P of the DF grapevines was 77% higher than that of theLF and WF grapevines. Daily fertigated grapevines bearing normal crop loads had 20% to 30% higherleaf blade P than the LF or WF grapevines. Leaf blade K of the WF grapevines was lower than in thegrapevines bearing a normal crop load of the LF and DF strategies. Grapevines bearing high crop loadstended to have lower juice N than grapevines with a normal crop load. Juice P of the DF grapevines washigher than that of the LF and WF grapevines, regardless of crop load. Daily pulse fertigation promotedthe accumulation of N, P and K in the berry skins

Comparison of Three Different Fertigation Strategies for Drip Irrigated Table Grapes – Part III. Growth, Yield and Quality

A field trial was carried out in a drip irrigated Dan-ben-Hannah/Ramsey vineyard near Paarl in the BergRiver Valley region of South Africa to compare three fertigation strategies. Fertilisers were applied (i)two weeks after bud break, fruit set and post-harvest (LF), (ii) weekly from two weeks after bud breakuntil ten weeks after harvest, except during berry ripening (WF), and (iii) in daily irrigation pulses (DF).Grapevines of all treatments received c. 116 kg/ha N, 22 kg/ha P and 92 kg/ha K per season. Grapevinesof all the fertigation strategies were thinned to obtain a normal and high crop load, which is 26 and36 bunches per grapevine respectively for Dan-ben-Hannah. Crop load did not affect vegetative growth,berry size or bunch mass. However, compared to LF and WF, DF increased the berry size of grapevinesbearing 26 bunches. Crop load tended to reduce juice TSS, irrespective of fertigation strategy, particularlyin 2002/03. Neither fertigation strategy nor crop load affected TTA and pH. Less berry crack contributedto a higher yield and higher export percentage of the DF grapes. In addition, bigger berries, and thereforebetter appearance, also contributed to the higher export quality of the DF grapes. Although the DFgrapevines bearing 36 bunches produced grapes of poorer colour and overall impression, they were withinexport norms. Based on the foregoing, the DF strategy should not be regarded as the ultimate solution fortable grape production. However, it can be recommended for vineyards on poor soils or where berry crackoccurs commonly

Effects of Liming to Near-neutral pH on Vitis vinifera L.

Wine grape vines are sensitive to soil pH and liming. The effects of pre-plant liming at rates sufficient to promoteaverage soil pH levels (1M KCl) of 5.05 (unlimed, treatment L0), 5.64 (L1) and 6.56 (L2) in two wine grape (scion)varieties and four rootstocks five years after planting were investigated over six seasons in a factorial field trial atStellenbosch. Yields tended to decrease in the sequence: L0 > L1 > L2, and were significantly (P = 0.05) lower in L2than in L0. Conversely, cane masses increased progressively with lime application rate, with L1 exceeding L0 by11.0% and L2 exceeding L1 by 13.0%. These increases were significant. Compared to L0, liming decreased the ratioof yield to cane mass by 13.6% in L1 and 28.8% in L2, but increased Ca:Mg ratios in the soil and petioles. Winequality was significantly better from L0 than L2. Petiole N concentrations were above normal in all treatments.Suppressed yields and wine quality in the limed treatments were attributed to a lime-induced imbalance betweenvegetative and reproductive growth, possibly exacerbated by increased Ca:Mg ratios and excess nitrogen

Effects of Rootstock on Grapevine Performance, Petiole and Must Composition, and Overall Wine Score of Vitis vinifera cv. Chardonnay and Pinot noir

Characteristics of Chardonnay and Pinot noir vines on Richter 99 (99R), Richter 110 (110R), Ruggeri 140 (140Ru)and SO4 rootstocks were assessed over six consecutive seasons in a factorial field trial on an Avalon soil in Stellenboschthat had been limed to pH 5.75 (1M KCl). Ruggeri 140 promoted the highest cane mass (vigour), highest petioleand must nitrogen (N), lowest ratio of yield to cane mass, and lowest overall wine quality. The lowest cane mass andhighest wine quality were produced by vines on 110R. Petiole N, phosphorus (P), calcium (Ca) and magnesium (Mg),and must N and Ca, were also lower for vines on 110R than for those on 140Ru

Dry Matter Accumulation, Seasonal Uptake and Partitioning of Mineral Nutrients by Vitis vinifera L. cv. Sultanina Grapevines in the Lower Orange River Region of South Africa - A Preliminary Investigation

Table grapes are harvested from November until early February in the Orange River Region of SouthAfrica, where a functional leaf canopy is present for up to six months of post-harvest. Seasonal uptakeand partitioning of mineral nutrients by ‘Sultanina’ grapevines in this long-season area were quantifiedin a preliminary investigation. Entire grapevines growing on two different soil types were sampled duringthe growing season. On sandy soil, further from the river, grapevine vigour was not excessive; however,on the fertile alluvial soil vigour was higher with active post-harvest re-growth. At budbreak, reserve Nplayed an important role on the sandy soil, while it was less important on the alluvial one. During the postharvestperiod, 34.3% of the annual N-requirement was absorbed by grapevines cultivated on sandy soilat post-harvest, while only 17.0% was absorbed on the alluvial soil. Approximately 4.0 kg N was utilizedfor the production of one ton of fresh grapes. A major fraction of the annual P-requirement (41.9%) wasabsorbed post-harvest by grapevines on the sandy soil. Grapevines on alluvial soil absorbed more P atpre-harvest; however, P was somehow lost post-harvest. Comparable amounts of K and Mg were absorbedby both selections of grapevines. Sandy soil grapevines absorbed K and Mg at post-harvest, while a netloss occurred for those of alluvial soil. Calcium utilized by sandy soil grapevines was less than half thatutilized by those of alluvial soil. The seasonal absorption pattern of Ca was comparable for both soils.Results suggest that that seasonal uptake and partitioning of mineral nutrients are affected by soil typeand grapevine vigour