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- Author or Editor: Heinz K. Wutscher x
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
Juice color of ‘Hamlin’ orange [Citrus sinensis (L.) Osbeck] on 30 rootstocks was determined at three harvests. Late harvest increased color scores. The mean color score over 3 years varied from 34.3 for juice of ‘Hamlin’ on trifoliate orange [Poncirus trifoliata (L.) Raf.] and Chu Kag mandarin (C. reticulata Blanco) to 33.2 on rough lemon [C. limon (L.) Burm. f.] and 32.9 on sour orange (C. aurantium L.). Scores >35 were found in single years, but no rootstock improved the color above a score of 36, the minimum for Grade A juice.
`Hamlin' orange (Citrus sinensis L. Osbeck) was grown on 15 rootstocks: four citrumelos [C. paradisi Macf. × Poncirus trifoliata (L.) Raf.], five mandarin × trifoliate orange hybrids (C. reticulata Blanco × P. trifoliata), two pummelo × trifoliate orange hybrids [C. grandis (L.) × P. trifoliata], Vangasay lemon (C. limon Burm. f.), Norton citrange (C. sinensis × P. trifoliata), and two Smooth Flat Seville (C. aurantium L. hybrid?) hybrids. These scion–rootstock combinations were compared to trees on Swingle citrumelo, the most widely used citrus rootstock in Florida. One Smooth Flat Seville hybrid was eliminated early because of poor growth and variability in size, and the Vangasay lemon rootstock was eliminated because of severe freeze damage. At age 5, the trees on Norton citrange developed citrus blight and were eliminated. Remaining in the experiment for 7 years, `Hamlin' trees on six of the 13 rootstocks produced more fruit than trees on Swingle citrumelo. Of these six, HRS 852 (Changsha mandarin × English large-flowered trifoliate orange) was the best overall rootstock, with trees on it producing large quantities of high-quality fruit on medium-sized canopies.
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
Grapefruit trees (Citrus paradisi Macf.) budded on Kama Khatta and sour orange were most productive in a test including 10 rootstocks. Karna Khatta, sour orange, and Yuzu were tolerant, ‘Orlando’ tangelo and ‘Ortanique’ tangor were intolerant of calcareous soil. Trees on Karna Khatta were more susceptible to foot rot than trees on sour orange.
Abstract
Leaf samples from 7-year-old avocado trees (Persea americana Mill. cv. Lula) grown with drip and flood irrigation were collected every 2 months for 2 years (2 leaf cycles) and analyzed for N, P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Cl-, and B. Mn and Cl- levels were significantly higher with drip irrigation; levels of the other 10 elements were not affected by irrigation method. Levels of 11 elements did not differ from year to year; only Fe was higher in leaf-cycle 1972-1973 than in leaf-cycle 1973-1974. There were seasonal changes in 10 elements; Na and Zn did not vary significantly with sampling date. Ca, Mg, Fe, Mn, and Cl- increased with leaf age; P, K, Cu, and B declined.
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
Rootstocks affected decay of grapefruit (Citrus paradisi Macf. cv. Redbush) stored for 9 weeks at 10°C plus 1 week at 21°. Fruit from trees on ‘Smooth Seville’ (Australian sour orange) was least susceptible to decay, 3.3%. Fruit from trees on the hybrid C61-253 (‘Shekwasha’ × ‘Chinotto’) was the most susceptible, 27.7%. Postharvest decay was statistically related to rootstocks but not to standard fruit quality characteristics.