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- Author or Editor: Heinz K. Wutscher x
- Journal of the American Society for Horticultural Science x
Abstract
One-year-old ‘Valencia’ orange [Citrus sinensis (L.) Osbeck] trees on rough lemon (C. limon Burm. f.), Carrizo citrange [Poncirus trifoliata (L.) Raf. × C. sinensis], and sour orange [C. aurantium (L.)] rootstocks were transplanted into 4 soil media and grown in the greenhouse for 2 years. Treatments were 1) the entire pot filled with 2 sand: 1 sphagnum peatmoss: 1 perlite (v/v/v); 2) the entire pot filled with 3 red clay: 1 sand (v/v); 3) the lower half of the pot filled with sand: sphagnum peatmoss: perlite and the upper half with clay: sand; 4) the lower half of the pot filled with clay: sand and the upper half with sand: sphagnum peatmoss: perlite. The trees were grown from February to October 1979 when the tops were cut off. A single shoot was allowed to regrow and the trees were harvested again in October 1980. The largest trees were on rough lemon rootstock; trees on Carrizo were slightly smaller, those on sour orange distinctly smaller. Trees on sour orange grew very poorly in treatments 1 and 4 when the whole medium or the upper layer was sand: sphagnum peatmoss: perlite. Trees on all rootstocks grew best in clay-sand over sand-sphagnum peatmoss-perlite. Rootstocks induced significant differences in 12 elements, the media in 10 of 14 elements determined in the leaves. They also affected K, Mg, Zn and water-soluble phenolics in wood and bark. There were rootstocks × medium interactions for growth, 13 elements in the leaves, and the 3 elements and phenolics in the wood and bark.
Abstract
Citrus trees affected with blight, a disease of unknown cause, were associated with soils having higher pH and Ca levels than soils under healthy trees. A detailed study of soil samples taken in 5-cm increments to a depth of 45 cm under healthy and blight-affected trees from five sites showed that pH, determined separately for each increment, showed significantly lower mean pH values under healthy trees. Double-acid (0.05 N HCI and 0.025 N H2SO4) extracts of soil under blighted trees contained more Ca at all five sites. Higher P and K were associated with blight in three of six and four of six comparisons, respectively. In one of five sites, Mn and Zn were higher and Fe lower under blighted trees. The soil under trees in very early stages of blight in the heavily affected part of a block compared with soil under trees in the healthy part of the block was higher in pH and Ca. Soil where lime was incorporated deeply by mixing or deposition of dredged calcareous subsoil on the surface was associated with the most severe incidence of blight.
Abstract
The shape of ‘Redblush’ grapefruit, Citrus paradisi Macf., grown in controlled environments was affected by the difference between day and night temperature. Fruit grown under a 32°/30°C day/night temperature regime had creased stem ends; a 32°/24° regime resulted in normal fruit, and 32°/7° induced severe sheepnosing. Reducing daylength from 14 to 11 hours had no influence on fruit shape.
Abstract
Air layers from 6 blight-affected and 6 healthy grapefruit, Citrus paradisi Macf., trees were grown in a greenhouse with low N, low S, and lime and high N, high S, and no lime regimes, one air layer from each tree in each treatment. Shoot fresh weight of air layers from healthy trees was 25%, and root fresh weight was 38% greater than that of air layers from blighted trees, after 8 months of treatment (shoot/root ratios of 1.59 and 1.90). Shoot weight was the same with both nutrient treatments; root weight was 40% smaller with high N, high S, and no lime than with low N, low S, and lime (shoot/root ratios of 2.12 and 1.37). Air layers from blighted trees had higher concentrations of N, P, and water-soluble phenolics, and lower Ca and Na in the wood; more S, Fe, Zn, Cu, and Mo in the bark; more N and K, and less Mg, Na, and Cl in the roots, and more P and less B and Cl in the leaves than air layers from healthy trees. Low N, low S, and lime induced higher K and Mo in the wood, higher K in the bark, and lower Na and Cl in the roots of air layers from blighted trees; high N, high S, and no lime increased Mg and Zn in the roots, Fe in the wood, and Zn in the leaves of air layers from blighted trees above the levels of healthy air layers. There were curvilinear relationships between evapotranspiration and root weight and the shoot/root ratio; air layers from blighted trees transpired more water than those from healthy trees on a per unit shoot and root weight basis.
Abstract
‘Hamlin’ orange, Citrus sinensis (L.) Osbeck, was grown on 30 rootstocks for 8 years in an area between Florida's east coast and Lake Okeechobee. There were eight five-tree replications in randomized blocks, with 3×6-m spacing. Yield and fruit quality were determined at four harvests and tree size (trunk cross sectional area) and tree losses were recorded. In general, tree on trifoliate orange [Poncirus trifoliata (L.) Raf.], trifoliate hybrids, and tangelo (C. paradisi Macf. × C. reticulata Blanco) rootstocks survived better than trees on mandarin, C. reticulata, and sour orange (C. aurantium L.) rootstocks. Most of the losses were due to tristeza virus and phytophthora root rot. The largest trees were on Volkamer and rough lemon (C. limon L. Burm. f.), F 80-18 citrumelo, C. paradisi × P. trifoliata, Troyer citrange, C. sinensis × P. trifoliata, and Sampson tangelo. Fruit production (kg/tree) was best on Volkamer lemon, Swingle, and F 80-18 citrumelo, and hybrid FF 1-131-20 (C. reticulata × P. trifoliata). In terms of kilograms of solids/tree, trees on Swingle and F 80-18 citrumelo, on hybrid FF 1-131-20, and on Sunshine tangelo were the most productive. Average juice content was low because of two late harvests, but other fruit characteristics were normal. Rind color was exceptionally good on Alamoen shaddock (C. paradisi).
Abstract
Nucellar red grapefruit, Citrus paradisi Macf., on ‘Swingle’ citrumelo, Poncirus trifoliata (L.) Raf. × C. paradisi, rootstock produced more fruit than trees on 20 other rootstocks over 9 years during the period when the trees were 6 to 14 years old. Fruit quality on ‘Swingle’ citrumelo was the same as on ‘Texas’ sour orange, C. aurantium L. Leaf analysis for 12 elements showed significant differences among rootstocks in the concentration of 7 elements, particularly a strong tendency of ‘Chinese box-orange’, Severinia buxifolia (Poir.) Ten., to accumulate Mn and of ‘Limon Real’, C. excelsa Wester, to accumulate Na.
Abstract
Yield, fruit quality, growth, and the levels of 12 elements in the leaves of 14-year old nucellar ‘Redblush’ grapefruit on 13 rootstocks showed that trees on Citrumelo C.P.B. 4475, ‘Morton’ citrange, and ‘Bittersweet’ sour orange were the most productive; those on ‘Ponkan’ mandarin, seedlings on their own roots, and sour orange were the least productive 3 . Two-year means of total soluble solids ranged from 10.3% for fruit from trees on ‘Bittersweet’ sour orange, ‘Carrizo’ citrange, and ‘Ponkan’ mandarin to 11.3% on sour orange. Fruit size was best on ‘Bittersweet’ sour orange and on Citrumelo C.P.B. 4475. Effects of rootstock on the levels of N, K, Mg, Mn, Zn, Na, and Cl and B in the leaves were statistically significant.
Abstract
‘Orlando’ tangelo (Citrus paradisi Macf. × C. reticulata Blanco) on 16 rootstocks was most productive on Swingle citrumelo, Morton citrange, Rangpur lime, and Cleopatra mandarin when the trees were 3 to 10 years old. Fruit quality was superior on Sun Chu Sha Kat, Keraji, and Kinokuni mandarins, hybrid C61-253 (‘Shekwasha’ × ‘Koethen’), Texas and Iwaikan sour orange, and Morton citrange rootstocks. Trees on Swingle citrumelo, Iwaikan sour orange, ‘Precoce de Valence’ sweet orange, Morton citrange, and Sun Chu Sha Kat mandarin had the largest canopies. Leaf levels of N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Cl-, and B varied significantly with rootstock.
Abstract
Virus-free nucellar budlines of red grapefruit and an old budline selection carrying exocortis and xyloporosis were grafted on sour orange rootstocks and grown under commercial conditions in the orchard. No differences were found in fruit quality. The old line trees produced the greatest tonnage of fruit for the first 7 years. By the tenth year the old budline trees were only 55-62% as large as the nucellar trees and were producing less fruit. Counting numbers of fruit above and below 96 ring size revealed no distinct differences in fruit size. This information should be vital to those concerned with early returns from citrus groves.
Abstract
Four-year-old nucellar ‘CES No. 3 Redblush’ grapefruit trees on 16 rootstocks, including 8 hybrids, growing on a calcareous soil of pH 8.4 differed in tree size and leaf color. Trees on sour orange, ‘Kunenbo’ mandarin and ‘Cleopatra’ mandarin rootstock were considerably larger and their foliage was greener than those of trees on other rootstocks. Trees on ‘Changsha’ mandarin, C61-250 (‘Shekwasha’ mandarin × ‘Koethen’ sweet orange) also were chlorosis-resistant but they were smaller than the trees on the other tolerant rootstocks. Rootstock effects on 10 mineral element levels in the leaves are discussed.