Rough Lemon Rootstock Research Articles

Phloem Zinc Accumulation in Citrus Trees Affected with Blight1

Abstract Zn content was higher in trunk bark (cambium to outer scrapings) than in the adjacent wood in healthy and blight-affected sweet orange (Citrus sinensis (L.) Osb.) and grapefruit (C. paradisi MacF.) trees. Zn levels were elevated in trunk bark and wood of blight-affected trees on rough lemon (C. limon (L.) Burnt, f.) rootstock, whereas affected seedling trees or trees on ‘Cleopatra’ mandarin (C. reticulata Blanco) rootstock that were tested had high Zn levels only in the bark. Bark Zn content was much higher above the bud union than below in blight affected trees on rough lemon or trifoliate (Poncirus trifoliata (L.) Raf.) rootstocks, but Zn content was high above the bud union in healthy trees only on rough lemon rootstock. The inner half of the bark, an area representative of the active secondary phloem, had much more Zn than the outer half of the bark or the most recently developed xylem. The outer half of the bark served as a barrier against outside contamination. Accumulation of Zn in wood occurred only when the phloem Zn was high.

The effect of hedging time on regrowth and flowering of mature Valencia orange trees

Thirty-eight-year-old Valencia orange trees on Rough Lemon rootstock were hedged at monthly intervals from September 1973 to April 1974. Trees were hedged on the east and west sides. Size of cut stem, number and length of each flush, and fruit number were recorded for each flush. Regrowth rate was highest on trees hedged in mid-summer, but by the winter of 1976 first flush length was similar on all treatments, and there were no significant differences in the total length per shoot or in the number of first or second flush shoots. The number of third and fourth flush shoots were reduced on autumn hedged trees. Stem circumference, rather than hedging time, was the major determinant of regrowth vigour. Approximately 50% of stems cut before December had flowering regrowth next spring. In the following year all hedging treatments produced flowering regrowth. It was concluded that mature Valencia citrus should be hedged after harvest and between spring and mid-summer. Autumn hedging should be avoided because it results in reduced fruiting.

Blightlike Citrus Tree Declines in South America and South Africa1

Abstract Water injection tests and analysis of the outer trunk wood for Zn, K, Mg, CI, and water-soluble phenolics of trees declining of declinamiento or fruta bolita (Argentina), marchit-amiento repentino (Uruguay), declinio (Brazil), and an unnamed decline in South Africa showed that these trees behave like blight-affected trees in Florida. Water uptake of declining trees is reduced, and Zn, K, Mg, and CI levels in the wood are usually higher than in healthy trees. Trees of ‘Valencia’, ‘Westin’, ‘Tarocco’, ‘Calderon’, ‘Natal’, ‘Alidjan’, and ‘Washington navel’ sweet oranges (Citrus sinensis (L.) Osbeck), ‘Eureka’ and ‘Lisbon’ lemons (C. limon (L.) Burm. f.), ‘Marsh’ grapefruit (C paradisi Macf.), and ‘Comun’ mandarin (C. reticulata Blanco) on trifoliate orange (Poncirus trifoliata (L.) Raf.), rough lemon (C. limon), Cleopatra mandarin (C. reticulata), and Rangpur (C. reticulata hybrid) rootstocks were used in this study.

The Influence of Rootstocks on Tree Growth, Yield and Fruit Quality of Valencia Oranges in Cyprus

SummaryCumulative yields per tree of Campbell Valencia orange during the first six years of production were significantly higher on rough lemon and Palestine sweet lime rootstocks than on Cleopatra mandarin and Troyer citrange, but not significantly higher than on sour orange. Rough lemon and Palestine sweet lime rootstocks produced significantly larger fruits than sour orange but quality was lower. Leaf analysis for eight elements showed significant differences in K, Mg and Mn but not in N, P, Cu, Fe and Zn.

The use of gibberellic acid to control alternate cropping of Late Valencia sweet orange

The effect of spraying commercial gibberellic acid (GA) on alternate cropping and yield of Late Valencia orange trees was studied in detail at three sites over three seasons. Two applications of GA were applied at a minimum concentration of 25 ppm (in two experiments 0.75% emulsifiable oil was used as an adjuvant) 3 weeks apart during April and May for Dareton (on the River Murray) or June and early July for Yanco (Murrumbidgee Irrigation Areas) prior to the heavy-crop blossom. These sprays partly inhibited flowering and the subsequent heavy crop was reduced by up to 22% (by fruit number). In the next season there were more flowers and the light crop was increased by up to 57% at Dareton and 228% at Yanco. Some treatments practically eliminated alternate cropping while all reduced considerably the heavyllight crop ratio. Mean weight yields over 2 years were increased by up to 17% at Yanco and 16% at Dareton with mean increases for all successful GA treatments of 12.6% and 7.2% respectively. This represented an increase of 34 and 24 kg fruitltree. No long-term adverse effects on yield were found.Apart from re-greening of the fruit present at the time of spraying, fruit quality was not affected. There were fewer non-saleable small fruit at Yanco in the heavy crop as a result of the GA treatments, and a better range of fruit sizes in both the heavy and light crops. Trees on Rough Lemon rootstock responded well to GA treatments, especially in terms of increased yield in the light crop. Poncirus trifoliata rootstock was less responsive than Sweet Orange. This method might be used for the commercial control of alternate cropping of Late Valencia orange trees.

Título en español.

El efecto en el crecimiento y rendimiento del chino (naranjo dulce) Valencia, el toronjo Marsh seedless y ortanique de seis portainjertos, se estudió en un experimento iniciado en Jamaica en 1965. Los resultados de esta investigación revelaron que, dentro de las condiciones de suelo y clima en que se realizó, los patrones de limonero rugoso (rough lemon) y de limero Rangpur fueron los más vigorosos, siguiéndoles el mandarino Cleopatra; mientras que el chino (naranjo) trifoliado decididamente fue el más débil. El naranjo agrio, tan extensamente usado como patrón, fue relativamente lento en crecimiento y casi igual al citrange Troyer en cuanto a vigor. Los datos de rendimiento recolectados en un período de 3 años entre 1969 y 1972 demostraron que con el patrón de naranjo agrio se lograron rendimientos de china (naranja dulce) Valencia, toronja Marsh seedless y ortanique tan buenos como con los más vigorosos de limonero rugoso y limero Rangpur, y a la vez mejores que con mandarino Cleopatra, citrange Troyer y chino (naranjo) trifoliado.

Factors controlling the accumulation of limonin and soluble constituents within orange fruits

AbstractA study was made of the differences in the quality and chemical constituents of the juice and albedo from Washington Navel and Valencia Late oranges grown at one orchard location on trifoliata orange and rough lemon rootstocks and harvested over a period of 40 weeks.Variety was the most significant factor in determining limonin contents, with rootstock an important subsidiary factor. Although limonin contents decreased absolutely as the season progressed, the maturity factor was important only in fruit of high initial limonin content. Differences in limonin contents were due to greater accumulation of limonin during fruit development and not to more rapid disappearance of limonin as the season progressed.An unknown factor controlled the distribution of limonin and soluble solids within the fruit, leading to the accumulation of these constituents in the blossom end. This “distribution factor” was so important that the differences in the limonin contents of albedo from the two halves of the same fruit were greater than the differences arising from the rootstock factor. For both limonin and soluble solids contents, the distribution factor operated uniformly throughout the season, irrespective of variety or rootstock.There was a direct relation between the chemical compositions of fruits picked at the same time from trees grown on different rootstocks, suggesting that relatively few picks could provide a basis for comparison of rootstock/scion combinations. The fact that such relations held irrespective of variety indicates an environmental effect on chemical composition which overrides varietal differences, whereas differences in variety and rootstock were more important in determining the physical characteristics of the fruit. Besides providing a basis for selecting fruit to give juice of optimum quality, these findings carry at least equal importance for the new light they throw on the physiological origins of variations in fruit quality.

Effects of N and K Fertilization on Internal and External Fruit Quality of Three Major Florida Orange Cultivars1

Abstract This is a report of a 4 × 4 NK factorial experiment over a 6-year period using ‘Hamlin’, ‘Pineapple,’ and ‘Valencia’ orange trees [Citrus sinensis (L.) Osbeck] on rough lemon rootstock (Citrus jambhiri Lush.) planted on Astatula f.s., formerly classified Lakeland f.s. Main effects of N and K were considered independently because interactions were not significant for most measurements. Increases in N rate increased the juice content and acid, whereas increases in K resulted in higher acid and lower soluble solids with an accompanying lower soluble solids/acid ratio. Smaller sized fruit, more green fruit, and a lower packout were a result of increased N rates. Increased K rates did not influence external characteristics of the fruit other than producing larger fruit. Rind blemishes occurred more often at the low N rate and diminished as the N rate increased. Incidence of decay in storage was greatest at the lowest N rate. Creasing was found to be significantly related to high N and low K rates.

N and K Fertilization Effects on Leaf Analysis, Tree Size, and Yield of Three Major Florida Orange Cultivars1

Abstract A 5-year field experiment planted on Astatula fine sand using ‘Hamlin,’ ‘Pineapple,’ and ‘Valencia’ orange (Citrus sinensis [L.] Osbeck) on rough lemon rootstock (Citrus jambhiri Lush.) with 4 levels each of N and K indicated that higher N rates increased fruit production and yield of soluble solids. High K applications decreased soluble solids. Increase in tree canopy area between 1968 and 1974 was related to N but not to K applications. Maximum yield response with N in all 3 cultivars was attained at 202 kg/ha/yr. ‘Hamlin’ orange showed maximum yield response to K at 167 kg/ha/yr whereas ‘Pineapple’ and ‘Valencia’ orange had maximum yield at 112 kg/ha/yr. Leaf analyses showed that increased N application resulted in higher leaf N and Mg contents but lower P and K levels. Increased K application showed higher P and K levels but lower Ca and Mg levels.

Yield and Tree Growth of Seven ‘Valencia’ Orange Type Cultivars on Four Rootstocks1

Abstract ‘Valencia’ cultivars (‘Campbell’ old line, ‘Campbell’ nucellar, ‘Frost’ nucellar, ‘Olinda’, ‘Cutter’, ‘Wood’, and ‘Chapman’) were budded on rough lemon (Citrus jambhiri Lush.), sour orange (C. aurantium L.), ‘Cleopatra’ (C. reshni Hort ex Tan.) and ‘Willowleaf (C. delicosa Tenore) mandarins. The first 5 were California cultivars with buds imported from the USDA Sub Tropical Fruit Station, Indio. The ‘Wood’ and ‘Chapman’ were local cultivars. All cultivars were disease free, excepting stubborn. Trees were planted in October 1959 near Peoria, Arizona and at 2 other locations. ‘Campbell’ old line produced highest yield at all locations. Fruit shape and quality were satisfactory, and tree growth vigorous. Up to 1966, trees on rough lemon rootstocks had the highest yield. Between 1968 and 1971, no difference in yield on trunk growth existed between trees on rough lemon, and ‘Willowleaf’ mandarin rootstocks. Lowest yield trees were on ‘Cleopatra’ mandarin.

Abnormal Bud Unions of Triumph Grapefruit and Related Varieties on Rough Lemon Rootstock

Abnormal Bud Unions of Triumph Grapefruit and Related Varieties on Rough Lemon Rootstock

Abnormal Bud Union Between Some Sweet Oranges and Rough Lemon Root-stock: Evidence of Cause by a Transmissible Pathogen

Abnormal Bud Union Between Some Sweet Oranges and Rough Lemon Root-stock: Evidence of Cause by a Transmissible Pathogen

The Residual Effects of Nitrogen, Calcium and Soil Management Treatments on Yield, Fruit Size and Composition of Citrus

SummaryA long-term field experiment testing the effects of 4 soil management treatments and 4 levels of ammonium sulphate on Washington Navel and Late Valencia oranges, budded on rough lemon or sweet orange rootstocks, was terminated in 1965. At this stage the difference in crop yield between the worst and best treatments was about 150%; average annual yields for the 4-year period 1962–65 varied from 18.3 to 46.2 t/ha according to treatment. After 1965 remedial N and Ca treatments were applied to restore the experimental area to a uniformly high level of productivity.For the 2-year period 1968–69, average annual yields from plots previously receiving the 4 ammonium sulphate treatments varied from 39.1 to 44.6 t/ha; uniformity in terms of yield had thus largely been achieved. Slightly less success, however, was achieved in terms of fruit quality.Lime, applied to counteract soil acidity induced by the previous ammonium sulphate treatments, produced greater responses on tilled plots than on non-tilled plots....

Assessment of citrus diversity in Ghana

Citrus is among the plant germplasm conserved at the CSIR - Plant Genetic Resources Research Institute (CSIR - PGRRI), Bunso in Ghana; however, due to lack of information on the specific traits of this germplasm at the Institute, the potential diversity within the collection is not yet fully exploited. The objective of this study was to evaluate the morphological diversity among the citrus accessions under conservation at the field genebank of the CSIR - PGRRI, Bunso, Eastern region of Ghana. The various accessions were raised on rough lemon rootstocks, planted using the augmented design. The citrus accessions evaluated include different citrus types suitable for different purposes, such as Flying Dragon for rootstock, Sweet Lime for medicine and Mediterranean Sweet for fruit drink. Late Valencia and Mediterranean Sweet were used as checks. Planting was done at 8 m by 8 m. Apart from watering immediately after planting, the plants grew under natural condition without irrigation. Variability was revealed by all the traits studied, including scion trunk surface, tree shape, tree growth habit and branch angle, based on IPGRI descriptors for citrus. The resulting phylogenic tree clustered the citrus accessions mainly based on known genetic relationships, using the clustering away of citrons from mandarins as an example. Although the morphological traits used in the characterisation were not sophisticated, they were useful in discriminating among the accessions. Based on this study, the citrus genebank at CSIR - PGRRI, Bunso, Eastern region of Ghana contains 44 morphologically distinct accessions. The information generated in this study is important for guiding conservation and utilisation decisions geared towards the improvement of the citrus sub-sector in the country.

The Effects of Tillage, Non-Tillage and Nitrogen on Yield and Fruit Composition of Citrus

SummaryOver the period 1947 to 1965 studies were made of the effects of four cultural treatments and four levels of ammonium sulphate on crop growth and fruit composition of Washington Navel and Late Valencia oranges, budded on to either Rough Lemon or Sweet Orange rootstocks. In terms of yield and quality, the best treatment combination was weed control by kerosene oil sprays together with 4 lb. of ammonium sulphate per tree per annum. For this treatment combination the average annual yield over the five-year period 1961–65 approached 500 lb. per tree.Almost all the nitrogen requirements of mature citrus trees were obtained from clover grown during March to September and then rotavated into the soil. Repeated ammonium sulphate applications caused soil acidity, aggravating an inherent soil phosphorus deficiency. Basal superphosphate applications, made since 1955 at an average annual rate of 4 lb. per tree, gradually improved fruit quality.From 1955 to 1965 small annual calcium carbonate applications of up...

Further Studies of the Bud-Union Abnormality of Rough Lemon Rootstocks with Sweet Orange Scions

Further Studies of the Bud-Union Abnormality of Rough Lemon Rootstocks with Sweet Orange Scions

Stem Pitting on Florida Rough Lemon Rootstock

Stem Pitting on Florida Rough Lemon Rootstock

Burrowing Nematodes May Survive on Variants of ‘Milam’ Lemon

Abstract ‘Milam’ is a lemon-type citrus rootstock of unknown parentage considered resistant to the burrowing nematode, Radopholus similis (Cobb) Thorne. R. similis causes a serious disease of citrus in Florida called spreading decline. ‘Milam’ was found in 1954 as the noninfected rootstock of a ‘Parson Brown’ orange tree in a burrowing nematode infested grove. In greenhouse tests of 9 months duration, ‘Milam’ consistently eliminated burrowing nematode populations from containers of infested soil by preventing the development of nematode eggs in the root cortex (3). After eight years in a rootstock trial planted in an infested site, no burowing nematodes were found in feeder roots of ‘Milam’ although nematodes were present in roots of adjacent rough lemon and sweet orange rootstocks (2). ‘Milam’ has also been tested as a biological barrier for four years in a soil tank 25 feet in length. Burrowing nematodes multiplied in one end of the tank have not migrated beyond the first ‘Milam’—a distance of two feet. Burrowing nematodes migrated 12 feet per year in a similar soil tank when susceptible rootstocks were used (1).

Burrowing Nematodes May Survive on Variants of ‘Milam’ Lemon

Abstract ‘Milam’ is a lemon-type citrus rootstock of unknown parentage considered resistant to the burrowing nematode, Radopholus similis (Cobb) Thorne. R. similis causes a serious disease of citrus in Florida called spreading decline. ‘Milam’ was found in 1954 as the noninfected rootstock of a ‘Parson Brown’ orange tree in a burrowing nematode infested grove. In greenhouse tests of 9 months duration, ‘Milam’ consistently eliminated burrowing nematode populations from containers of infested soil by preventing the development of nematode eggs in the root cortex (3). After eight years in a rootstock trial planted in an infested site, no burowing nematodes were found in feeder roots of ‘Milam’ although nematodes were present in roots of adjacent rough lemon and sweet orange rootstocks (2). ‘Milam’ has also been tested as a biological barrier for four years in a soil tank 25 feet in length. Burrowing nematodes multiplied in one end of the tank have not migrated beyond the first ‘Milam’—a distance of two feet. Burrowing nematodes migrated 12 feet per year in a similar soil tank when susceptible rootstocks were used (1).

Severe copper deficiency in orchard grapefruit trees

does not appear. First page follows. Introduction In the winter of 1958 several grapefruit orchards near Hemet, California, developed severe copper deficiency symptoms. Because this deficiency is rarely seen in the field in California, its appearance in severe form presented an excellent opportunity for study of the diagnostic symptoms, for laboratory verification through leaf and soil analysis, and for field correction of the deficiency. This paper is a report of copper-deficiency symptoms as they appeared in the grapefruit, and of the use of sprays to achieve full recovery. Materials and Methods Experimental Orchards The three grapefruit orchards studied are located on Hanford sandy loam soil. Orchard A comprised 27 acres of Ruby red grapefruit scion on rough lemon rootstock, while orchard B comprised about 10 acres of Marsh grapefruit scion on rough lemon rootstock. Adjacent to these 10 acres of grapefruit were about 5 acres of Valencia oranges (orchard C) on rough lemon rootstock. Orchard D was a poor-appearing young grapefruit orchard (rootstock unknown) located about a mile south of orchard C. Leaf Sampling and Analysis Spring cycle leaves 4 to 6 months old were taken from fruiting terminals. In each case 10 leaves from each of 10 trees comprised the sample. Leaves were individually washed in tap water and Ivory soap, rinsed in tap water, and dried with clean cloths; this method of leaf washing has been employed in laboratories of the department of Soils and Plant Nutrition at Riverside, California for many years and has been subjected to thorough testing (Wallihan, 1953).3 The samples were then oven dried at 55° C and crumbled by hand previous to weighing a 2-gram sample for spectrographic analysis. Micro-element determinations were made by the spectrochemical method of (Vanselow et al. (1948)). Soil Sampling and Analysis Virgin soil samples of the 6 to 8-inches depth were collected from areas surrounding the orchards showing severe copper deficiency symptoms. Samples were analyzed for total copper by the method of (Pratt and Bradford (1958)).