The Influence of Phosphorus Availability, Scion, and Rootstock on Grapevine Shoot Growth, Leaf Area, and Petiole Phosphorus Concentration R
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The Influence of Phosphorus Availability, Scion, and Rootstock on Grapevine Shoot Growth, Leaf Area, and Petiole Phosphorus Concentration R. STANLEY GRANT ~* and M. A. MATTHEWS 2 Cabernet Sauvignon (CS) and Chenin blanc (Cb) scions on Freedom, AxR#1, St. George, and 110R rootstocks were grown under conditions of sufficient (+P) and deficient (-P) soil phosphorous availability. Shoot length, shoot dry weight, leaf area, and petiole P concentration were lower for -P compared to +P vines. Cb vines had larger leaves and more leaf area than CS vines and the leaf area of Cb vines was less inhibited by exposure to -P than was CS vines. Vines on Freedom had longer shoots, greater shoot biomass, and greater leaf area than vines on other rootstocks regardless of P availability. Under +P vines on St. George produced less shoot dry weight than vines on Freedom, but more than vines on 110R. However, the shoot dry weight and leaf area of vines on St. George was greatly inhibited by -P and vines on St. George appeared to not use P efficiently for growth under these conditions. Vines on 110R produced the least amount of shoot growth and leaf area among the rootstocks under +P, but were also the least inhibited by -P conditions. The shoot dry weight and leaf area of vines on AxR#1 was intermediate between vines on Freedom and vines on St. George and 110R, and were inhibited by -P slightly less than St. George. Freedom and 110R are more suitable for low P soils than St. George and AxR#1. KEY WORDS: Vitis, grapevines, phosphorus, scion, rootstock, shoot growth, shoot elongation, leaf area, Cabernet Sauvignon, Chenin blanc In California, phosphorus (P) deficiency has been Information on the influence of grape scion and interac- observed in vines growing in soils of low pH (11). Soil tions between scion and rootstock with regard to vine phosphorus is taken up by plants in the inorganic, nutrient status, growth, and yield is also very limited orthophosphate form (17,26). Acidic soils are favorable (29), although ungrafted varieties that are normally environments for ligand exchange and precipitation used as scions are known to differ in petiole P concen- reactions that make orthophosphates unavailable to trations (4,6). The purpose of this study was to evaluate plants (2,19,31). grapevine shoot growth responses to P deficiency P deficiency inhibits the initiation and mainte- among a genetically diverse group of scion/rootstock nance of cluster primordia and, hence, fruit yield of combinations, including those commonly grown for grapevines (34). In field trials, soil applications of P wine grape production in areas of California. fertilizer have successfully corrected P deficiencies, but Materials and Methods the cultivars Chardonnay and Chenin blanc differed greatly in the lamina P concentrations associated with Cabernet Sauvignon (CS) and Chenin blanc (Cb) maximum yield (33). This observation and others of scions were included in the experiment. Both are Vitis genotypic differences within crop species in the effi- vinifera cultivars with vigorous growth habits (15,22). ciency of P utilization (16) indicate that informed culti- Each of the two scions were grafted to the rootstocks var selection could minimize the need for P fertilizer. Freedom, Aramon Rupestris Ganzin no. 1 (AxR#1), Rupestris St. George (St. George), and 110 Richter The potential to exploit genetic variability in min- (ll0R). Freedom is a complex hybrid whose parentage eral nutrition may be greater when vines are grafted includes 1613 Couderc, a Solonis (V. riparia x V. rupes- due to interspecific variation among rootstocks in nu- tris x V. candicans) x Othello (V. labrusca x V. vinifera) trient uptake and translocation to scions (14). Grape hybrid, and Dogridge, a selection of V. Champini (23). rootstocks have been shown to differ in their influence AxR#1 is a hybrid of V. vinifera cv. Aramon and V. on scion nutrient status, growth, and yield (7,9,35), but rupestris cv. Ganzin (15,23). St. George is a selection of the influence of rootstock on grapevine P nutrition, V. rupestris (15,23). The rootstock ll0R is a V. berland- particularly under P deficiency, is not well understood. ieri cv. Ressequier no. 2 by V. rupestris cv. Martin cross (15,23). Plant materials originated from dormant wood 1Viticulturist, Duarte Nursery, Inc., 1555 Baldwin Road, Hughson, CA 95326; 2Associate Profes- derived from University of California, Davis, vineyards sor, Department of Viticulture and Enology, University of California, Davis, CA 95616-8749. and were bench grafted by the Department of Viticul- *Corresponding author. ture and Enology field staff. Acknowledgement: The authors wish to thank the Phosphate and Potash Institute for their financial support, P. W. Skinner and R. M. Carlson for their technical advise, and E. Hall for making Grapevines were planted in a 1:1:1 mix of sphag- the bench grafts used in this study. num peat moss, sand, and silt from the stream bed of Manuscript submitted for publication 1 February 1995. Putah Creek near Davis, California. The pH of the air Copyright © 1996 by the American Society for Enology and Viticulture. All rights reserved. dry mix was 5.7 as measured by the 1:2.5 air dry 217 Am. J. Enol. Vitic., Vol. 47, No. 2, 1996 218- GRANT and MATTHEWS soil:water suspension method (27). The available P level of the soil was 8 mg/kg of air dry soil by the Bray 1 Table 1. Formulas for calculated parameters. procedure as described by Knudsen (3,24). This is the critical concentration for soil P deficiency for most agro- Parameter Formula nomic crops (21). The grapevines were grown in a greenhouse in 11-L Inhibition due to (value for +P vine)-(value for -P vine) pots containing the mixture described above for about P deficiency (100) (value for +P vine) 13 weeks to deplete the supply of P stored in the graft wood and roots. Plants were then unpotted, the shoots Mean area per leaf leaf area per plant pruned to a single 2-node spur, and the roots pruned to number of leaves per plant a length of about 5 cm before replanting each in an 11-L pot in the same low-P potting medium used previously. Specific leaf area z leaf area per plant laminae dry weight Roots were trimmed to equalize the root system size, absorptive surface area, and P reserves among the Leaf area per unit shoot weight shoot leaf area vines. shoot dry weight The experiment had three factors. Two factors, Leaf area per unit shoot length shoot leaf area scion and rootstock, were genotypic and the combina- shoot length tion of the two formed the composite experimental units. The third factor was P treatment. Each scion- zAfter Evans (12). rootstock-P level combination was replicated four times as single potted vines. The vines were arranged in pairs Petioles were used as indicators of grapevine P status with respect to P treatment such that within a replicate because past workers used them extensively, found block a +P vine of a given scion and rootstock was them to be convenient and reliable indicators of vine P paired with a -P vine of the same scion and rootstock. status, and developed diagnostic criteria based on them Pairing was adopted to facilitate the calculation of inhi- (1,5,8,10). Dried petioles from the lowest 10 nodal posi- bition of growth parameters due to exposure to P defi- tions on the shoot were ground to a powdery texture ciency (see below). The pairs were arranged in a ran- with a sample mill and stored in plastic vials until they domized complete block design. could beanalyzed. Petiole P status was analyzed using Essential plant nutrients other than P were added a 2% acetic acid extraction and ammonium molybdate- to the -P vines in the form of a modified 1/4-strength ascorbic acid color development procedure (32). Hoagland solution (18) that did not include P. Thus, the Table 1 lists the parameters that were calculated low level of P available in the medium established the P from those measured. Inhibition due to exposure to P level of the -P treatment. The +P vines received a deficiency represents the decrease in a parameter for a quantity of nutrients comparable to that received by-P -P vine relative to a paired +P vine. vines plus 0.3 mM phosphate-P. Nutrient solutions Analysis of variance was performed to identify were applied once per week as an irrigation during the scion, rootstock, and P level effects and interactions. experiment. Means for rootstocks were separated by Tukey's signifi- Budbreak occurred about one week after replant- cant difference. This procedure was selected because, ing. Shoots were thinned to one per vine four days later. unlike Fisher's least significant difference (LSD) and The shoot was trained vertically to maintain the apical Duncan's multiple range, the comparison wise level of dominance of the shoot tip. Vines were irrigated twice a significance is adjusted for the number of comparisons week until their shoots were about 50 cm long, when being made so that the desired experiment-wise level of the number of irrigations was increased to three per significance is maintained (20,30). Consequently, week. The greenhouse temperature near the plants Tukey's significant difference is a relatively conserva- averaged 26°C, with the average nighttime low being tive test that facilitated meaningful comparisons of 19°C and the average daytime high being 30°C as mea- mean values for the different rootstocks included in sured by a hygrothermograph. The mean relative hu- this study. midity was 58% with an average diurnal range of 43% to 73%.