Effect of fruit-load on the growth,absorption, and partitioning of inorganic nutrients in young ‘Fuyu’ persimmon trees

Tree growth and the increase in inorganic nutrients during a growing season were studied in 3-year-old, container-grown ‘Fuyu’ persimmon trees with different levels of fruit-load. Fruit-load was varied by adjusting the leaf–fruit ratio to 10, 20, 30, and 60 on July 5. Some trees were completely defruited. The whole trees were harvested on November 5 of that year, and increases in dry weight and inorganic elements in different tree parts during the season were measured. A lower leaf–fruit ratio resulted in a higher yield but also decreased fruit weight, soluble solids, and fruit color. Dry weight of the aerial woods and root increased significantly with a greater ratio. However, total dry weight including the fruits was higher in the lower ratio trees than in the higher ratio trees; the weight of a tree that maintained the ratio of 10 was 35% higher than a tree without fruit. Fruits accounted for 62% of total dry weight when the ratio was 10 and 27% when the ratio was 60. The leaf–fruit ratio did not significantly alter the total increase in P, K, Ca, and Mg content. N tended to decrease with an increasing leaf–fruit ratio. Of the total increases of N, P, and K during the season, the fruits accounted for 30%, 50%, and 54% at the ratio of 20, respectively, and the percentages increased to 44, 81, and 74 at the ratio of 10. The inorganic element content in the aerial woods and root tended to increase with greater ratios, especially in the root. When trees were defruited, N and K increases in the root accounted for 44% and 35% of the total increase, respectively. These results indicated that persimmon orchard fertilization programs with different fruit-load levels should accommodate the proportion of nutrients partitioned to fruits that are removed permanently from the tree.     

Status of nitrogenous and carbohydrate compounds as affected by nitrogen fertigation rates in young persimmon trees

The effects of nitrogen (N) fertigation rates on levels of nitrogenous and carbohydrate compounds were determined in young ‘Fuyu’ persimmon trees. Total N amounts of 0 g, 10 g, 20 g, 30 g, and 40 g were distributed, respectively, to a 50-L pot by fertigation as different volumes of 1% (w/v) urea solution every week from May 15 to September 25. Fruits were sampled on November 2, and shoots and roots on November 17. High N fertigation rates significantly increased the N and amino acids in all the tree parts and protein in fruits and shoots. In contrast, the concentration of soluble sugars significantly decreased in the fruits and perennial parts as the N rate increased from 10 g to 40 g. A notable reduction of starch was also found in the shoots and roots of trees with high N fertigation rates. The percentage of shoots died due to cold injury during the winter was the highest at the 0 g N rate; however, it was 2.3-fold greater at the 40 g N rate as compared to the 10 g N rate. We concluded that high N fertigation could interfere not only with sugar accumulation of fruits through increased N metabolism, but also reserve carbohydrates of perennial organs.     

Effect of different girdling dates on tree growth,fruit characteristics and reserve accumulation in a late-maturing persimmon

Trunks of 8-year-old vigorous ‘Fuyu’ persimmon (Diospyros kaki Thunb.) were girdled to a 1 cm width on April 20 and June 10 2004. Tree growth and fruit characteristics were monitored for two years, with special emphasis on the carry-over effect in 2005. Girdling reduced trunk and shoot growth especially of April-girdled trees over two consecutive years. However, the most significant effect of girdling was in the occurrence of water sprouts: a control tree had 29.5 in 2004 and 27.3 in 2005, whereas the April-girdled trees had only 0.3 and 5.3, respectively. Girdling increased fruit set by nearly 50% and enhanced fruit colour in 2004 only. Girdling date did not significantly affect fruit size and soluble solids for two years. Fruit flesh of girdled trees in 2004, especially in the April-girdled trees, had lower N and P concentrations. The levels of starch, soluble sugars, and inorganic elements in flower-bearing distal buds measured just before new growth in 2005 were not significantly altered by the girdling in 2004.     

Defruiting effect of young Fuyu persimmon (Diospyros kaki) on assimilate partitioning in-season and early growth the next season

Changes in the distribution of dry matter and nonstructural carbohydrates in various parts of young ‘Fuyu’ persimmon (Diospyros kaki) were examined with 3- and 4-year-old trees with (fruited) and without fruits (defruited). The effect of such changes was then monitored with regard to the magnitude of new growth the following year. From June 15 to November 1, fruiting significantly decreased the rate of dry weight accumulation in perennial parts of the tree. Dry matter was partitioned the most to fruits (68–72%) and the least to the roots. Of the total dry weight, root accounted for 8–27% in fruited and 58–62% in defruited trees. During this period, soluble sugars were three times more in fruited than in defruited trees, but more than 95% of sugars were in the fruits. Starch content increased in defruited trees, more than 93% of which being distributed to the perennial parts. Compared with fruited trees, defruiting in the previous year increased new shoot growth and the number of fruits the following year, with a 20–58% greater increase in dry matter. During the new growth from April 10 to June 10 the following year, root dry weight decreased by 30–32% in defruited trees, whereas it increased by 20–80% in the fruited ones. Soluble sugars in roots decreased by 8.8–19.7 g in defruited trees but increased by 9.7–12.3 g in fruited ones. Starch in roots decreased by 68–75.1 g in defruited trees but increased by 10.2–13.3 g in fruited ones. However, there were no significant differences in soluble sugars and starch in the newly grown parts. It was estimated that a 1-g difference in dry matter accumulated in the previous season resulted in a 116-mg and 256-mg difference in dry weight of newly grown parts, and a 6.5-mm and 17.5-mm new shoot in the following season for 3- and 4-year-old trees, respectively.     

Fruit set and embryo rescue in crosses using parthenocarpic ‘Mopanshi’ persimmon

The ‘Mopanshi’ persimmon is a seedless, astringent parthenocarpic cultivar that does not produce male flowers. After pollination using four non-astringent cultivars (‘Zenjimaru’, ‘Nishimurawase’, ‘Okugosho’ and ‘Hanagosho’), seeds were produced to different degrees. ‘Mopanshi’ fruits pollinated with ‘Zenjimaru’ produced far more seeds than those pollinated with the other three cultivars. The ratio of abnormal seeds obtained from the fruits pollinated with ‘Hanagosho’ was higher than that obtained from the fruits pollinated with the other three cultivars. Most embryos degenerated in the early to late stages of seed development. Immature embryos were cultured in a modified MS medium (half of NO₃ in MS medium + 0.4 μM BA + 0.1 μM IBA) with the greatest success (52–80%) from embryos taken from fruits 60–80 days after pollination. Seedlings failed to initiate radicles so they were transferred to dark culture conditions for 8 days or to a rooting media that contained 3% sucrose and 1% Chinese ink. The seedlings on the medium darkened with ink rooted at greater than 90.83% compared to 75.83% for dark cultured seedlings. This study demonstrated that ‘Mopanshi’ persimmon could be used as a female parent in crosses, but embryos needed to be moved to tissue culture conditions to continue to develop and form plantlets.     

Dry weight and carbohydrate distribution in different tree parts as affected by various fruit-loads of young persimmon and their effect on new growth in the next season

This study was conducted to determine the changes in the accumulation of dry weight (DW) and the distribution of carbohydrates in different parts of young persimmon (Diospyros kaki) as affected by various fruit-loads. The effects of such changes were monitored with regard to the abundance of new growth in the following year. On June 15, the fruit-load was adjusted to a leaf–fruit (L/F) ratio of 10, 20, and 30, and some trees were completely defruited. Between June 15 and November 11, the increase in DW was less in the defruited and more in the higher L/F-ratio trees. Among the various tree parts, the DW increased the most in the fruits during the same period. It was observed that the lower the L/F ratio, the more the DW in the fruits: the fruits accounted for 78.7% of the total DW in the 10-L/F, 57.6% in the 20-L/F, and 49.7% in the 30-L/F ratio trees. In contrast, as the L/F ratio increased, the DW distribution to the roots increased to 3% in the 10-L/F, 13% in the 20-L/F, and 26% in the 30-L/F ratio trees and 61% in the defruited trees. During this period, carbohydrates were distributed mostly to the fruits, but as the L/F ratio decreased, their distribution to permanent tree parts decreased. The distribution of soluble sugars and starch to the permanent parts was 1% and 14% in the 10-L/F, 3% and 48% in the 20-L/F, 9% and 57% in the 30-L/F ratio trees, and 71% and 93% in the defruited trees, respectively. Maintaining a lower L/F ratio resulted in a decrease in the shoot and fruit numbers in the following year: there were zero and four fruits in those trees with an L/F ratio of 10 and 20, respectively. The carbohydrates decreased in the roots of both the 30-L/F ratio trees and the defruited trees, whereas the defruited trees showed more new shoot growth in the following year. In the roots of the trees with the L/F ratio of 30, soluble sugars and starch decreased by 7.6 g and 1.8 g, respectively, during the spring growth, whereas, in the roots of the defruited trees soluble sugars and starch decreased by 33.3 g and 94.6 g, respectively.     

Estimation of the proportions of offspring having soft fruit and juicy fruit as evaluated by sensory tests in Japanese persimmon

Firmness and juiciness are important fruit attributes targeted in the breeding of Japanese persimmon (Diospyros kaki Thunb.). To facilitate the efficient production of cultivars with soft and juicy fruit, we successfully used the mid-parental values (MP) of sensory evaluations as independent variables in logistic regression models to estimate the proportions of offspring from a given cross that would have soft fruit and juicy fruit. The best model for estimating firmness contained only the MP for firmness (MPf) as an explanatory variable, whereas the best model for juiciness contained both the MP for juiciness (MPj) and the MPf as explanatory variables. The regression lines from these models suggested that crosses with a low MPf and high MPj can increase the proportion of offspring that have soft fruit and juicy fruit, respectively. However, the slopes of the regression lines for both firmness and juiciness were gentle, indicating that genetic segregation in offspring is wide for both attributes. We infer from these data that softer and juicier fruit can be bred from parents having only moderate ratings for these traits.     

Effects of CPPU on fruit set and fruit growth in Japanese persimmon

The effects of hand-pollination and spraying with N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) on fruit set and fruit growth of ‘Matsumoto-Wase-Fuyu’, which is a member of the pollination-constant, non-astringent group of persimmons (PCNA) were investigated. Staminate flowers of pollinizers in the orchard were eliminated before anthesis. Hand-pollination was carried out at full bloom (FB). Without prior hand-pollination, CPPU at 5 or 10 mg 1⁻¹ was sprayed 11 days after FB. Hand-pollination and spraying with CPPU increased fruit set before thinning of fruits by hand. The number of fruits after thinning did not differ among treatments. The yield of marketable fruits after hand-pollination was similar to that after treatment at 5 mg 1⁻¹, but was higher than that for untreated trees. Formation of a sunken fruit apex, which was observed in about 30% of fruits from untreated trees, was suppressed by application of CPPU. CPPU also delayed coloration of fruit. There were no differences among treatments in firmness or soluble solids concentrations of marketable fruits.     

Ascorbate levels and the activity of key enzymes in ascorbate biosynthesis and recycling in the leaves of 22 Chinese persimmon cultivars

The objective of this study was to determine diversities of ascorbic acid (AsA) and activities of enzymes involved in AsA metabolism, and to determine their relationships to AsA content in the leaves of Chinese persimmon (Diospyros kaki) cultivars. Results showed that there were huge differences not only in the contents of AsA and glutathione (GSH) but also in the enzyme activities of l-galactono-1,4-lactone dehydrogenase (GLDH, EC 1.3.2.3), dehydroascorbate reductase (DHAR, EC 1.8.5.1), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) in the leaves of 22 Chinese persimmon cultivars. Control of AsA levels mainly depended on the capacity for biosynthesis and GLDH activity played a main role in determining AsA levels in the leaves of persimmon. Both MDHAR and DHAR, MDHAR in particular, also played an important role in maintaining AsA redox state by reducing oxidized AsA back to AsA. But contents of GSH and hydrogen peroide (H₂O₂) and activity of APX were not significantly correlated with AsA content in the leaves of persimmon.     

多胺在果实生长发育中的作用研究进展

多胺是广泛存在于植物体内的具有生物学活性的低分子量脂肪族含氮碱。它在植物的胚胎发育、花和果实的发育等生长发育过程具有重要的调控作用,同时在延缓植物衰老和抗逆境等方面也具有重要意义。近几年的研究表明多胺代谢同植物开花坐果、果实发育甚至果实品质特性密切相关。概述了多胺对果实坐果,膨大与衰老等果实发育生理过程的影响,并对多胺在果实逆境发育中的作用进行了探讨,对多胺在果实发育过程中可能的调控作用机理以及外源多胺在植物开花坐果上的应用潜力进行了讨论,并展望了多胺作用分子机理的研究前景。     

Relationship between light,fruit and leaf mineral content with albinism incidence in strawberry (Fragaria x ananassa Duch.)

A study was conducted in strawberry to establish a relationship between shading, mineral nutrient of leaves and fruits with albinism incidence. Plants grown under shade produced albino fruits in higher proportion than those grown in open fields. Similarly, plants under shade produced smaller sized fruits and have lower fruit yield. Among cultivars, Etna had highest incidence of albinism (49.6%) and Sweet Charlie the lowest (14.4%). Dry matter content (%), concentration of five major nutrients, viz. N, P, K, Ca, Mg, S and N:Ca and K:Ca nutrient ratios did not differ significantly in the leaves of plants producing normal or albino fruits. However, in contrast, the concentration of K was notably higher (1.97 mg g⁻¹ fresh tissue weight) and that of Ca was lower (0.098 mg g⁻¹ fresh tissue weight) in albino fruits than normal ones. Consequently, the ratios of N:Ca (11.34) and K:Ca (20.08) were higher in albino fruits than normal ones. Cultivars also differed widely in respect to dry matter (%), mineral content and nutrient ratios. Thus, it appears that lower light intensity favours the development of albinism in strawberry, and it seems that calcium is not the basic cause of albinism, but increased vigour associated with overuse of N and K might be positively associated with it.     

Effect of split applications of oil cake on leaf nutrient contents,tree growth,and fruit quality in non-astringent persimmon trees

Oil cake, widely used as an organic source of nutrients in horticultural production in South Korea, is a by-product when oil is extracted from various oilseeds. Split applications of oil cake were supplied to evaluate their effects on tree growth and fruit production in organic, non-astringent persimmon (Diospyros × kaki Thunb.) trees in 2009 and in 2010. Treatments included a single annual application of oil cake at 150 kg N ha^?1 in April (single application), two applications in April and July (105 and 45 kg N ha^?1, respectively; two-split application), or three applications in April, June, and August (60, 45, and 45 kg N ha^?1, respectively; three-split application), as well as zero application of oil cake (control). All applications of oil cake significantly increased the amount of ground-cover vegetation compared to the control. The single and two-split applications increased soil organic matter (OM), K₂O, CaO, and MgO concentrations, and cation exchange capacity to a soil depth of 0–30 cm in 2010. Oil cake applications increased soil porosity in 2010, as well as overall chlorophyll (SPAD values) and macronutrient concentrations in leaves in 2009 and 2010. Single and two-split applications stimulated water-sprout development, reduced the light intensity inside the tree canopy, and increased fruit drop. Fruit yield was higher in the two-split [24.7 metric tonnes (MT) ha^?1] and three-split application trees (25.0 MT ha^?1) compared to zero application control trees (19.8 MT ha^?1) and single application trees (21.0 MT ha^?1) in 2010. A single application resulted in soft fruit and slow skin colouration during maturation. Total soluble solids contents were higher in the control and three-split application trees in both years. The three-split application in 2010 increased the estimated production income by approx. 21% compared to the zero application, and by approx. 33% compared to a single application of oil cake.     

Long-term effects of managed grass competition and two pruning methods on growth and yield of peach trees

Ground cover competition and tree training strongly affect development of newly planted peach trees and eventual productivity of peach orchards. This experiment characterized the long-term interactive effects of three levels of competition and two pruning criteria on yield, fruit size, and marketable yield efficiency. Trees of two cultivars (’Jersey Dawn’, JD, and ‘Redskin’, RS, on Lovell) of peach (Prunuspersica (L.) Batsch) were planted in an orchard in 1993 and grown for 14 years in a vegetation free area (VFA) width of 0.6 or 2.4 m. A separate group of trees that were in the 2.4 m VFA had grass seeded beneath them in 1998 to obtain 0 m VFA. All trees were pruned to maintain canopy size with wide-angled scaffold limbs and intense pruning (IP) or upright branch form with reduced pruning (RP). In general, RS had greater yield than JD and yield was greatest in the 2.4 m VFA with RP and least in the 0.6 m VFA with IP. Cumulative marketable (≥6.35 cm) and average annual total yield of both cultivars was similar for RP trees in 0 m VFA and IP trees in 2.4 m VFA's although more of the fruit were in the largest size class (>6.98 cm) in the IP trees. Reduced pruning increased crop load. Fruit weight decreased with increased crop load more in RS than JD and this response was similar for all VFA's within each cultivar. Grass competition tended to reduce both the number and weight of fruit per tree but the average weight of individual marketable fruit was reduced only in the 0.6 m VFA of RS. Tree size was reduced by grass competition and pruning times measured from 1995 to 2000 were less in RP than IP. Consequently, marketable yield efficiency of marketable fruit (grams fruit ≥6.35 cm/cm² trunk cross-sectional area, TCSA) measured from 2004 to 2007 was generally greater in trees with RP than IP and in the 0.6 than the 0 and 2.4 m VFA. The results indicate that persistent competition will reduce total annual yield per tree but with reduced pruning the concomitant increased crop load can help maintain marketable yield.     

Relationship of leaf necrosis and defoliation to phosphorus and potassium concentrations in selected tissue and to certain fruit quality parameters of pecan

Pecan [Carya illinoinensis (Wangenh.) K. Koch] trees developed necrotic areas in the leaves late in the growing season. July samples indicated that leaf P (0.114% DW) and K (0.62% DW) were low, but other elements were within accepted sufficiency ranges. Relationships between leaf P and K concentrations with nut quality and return bloom were determined. Trees were rated for leaf necrosis 1 October using a 1 (none)–5 (severe) scale. Fruit were harvested and analyzed for weight/nut, kernel weight, and kernel grade. Leaflet pairs collected 1 October from fruit bearing shoots were analyzed for N, P and K. Return bloom was determined on branches that bore fruit the previous year. Necrosis ratings were positively related to leaf N and negatively correlated with weight/nut; kernel, shuck and leaf P concentrations; and kernel and leaf K concentrations. Leaf, kernel and shuck P concentrations were positively correlated with weight/nut and percentage number 1 kernels. Leaf K was positively correlated with return bloom and weakly negatively correlated to weight/nut. Phosphorus was the primary element limiting fruit development and K shortage substantially reduced return bloom. Data support minimum pecan leaf standards in July for fertility recommendations of 1.0% K and 0.14% P.     

Olive fruit pulp and pit growth under differing nutrient supply

The objetive of this work was to study if the addition of nutrients to the irrigation water modified ‘Manzanilla de Sevilla’ olive pulp and pit growth. The experiment was carried out during the 2003 fruit-growth period in an irrigated orchard near Seville, southern Spain. Fruit samples were taken in July and September, at 12 and 21 weeks after full bloom (AFB) respectively, in trees irrigated with (T1) or without (T0) the addition of nutrients (N–P–K). The nutrient availability of T1 fruits increased the fruit fresh and dry weight, longitudinal and equatorial diameters, and the pulp-to-pit ratio, characteristics particularly appreciated for table olives. The balance of growth between the fruit mesocarp (pulp) and endocarp (pit) was modified because those two tissues were affected differently. Mesocarp fresh weight was significantly higher at both 12 and 21 weeks AFB in the fertilized treatment, as was mesocarp dry weight at 12 weeks AFB. Neither the endocarp fresh and dry weight nor shape (the ratio of the equatorial and longitudinal diameters) was altered at either of the two studied dates. These results emphasize the importance of an appropriate fertilization management in irrigated olive orchards, particularly for table olives, and also confirm the olive endocarp as a strong sink tissue that competes with the mesocarp during early development.     

Canopy profiles of starch and leaf mass per area in greenhouse tomato and the relationship with leaf area and fruit growth

Better knowledge of patterns of carbon allocation in plants growing in CO₂-supplemented atmospheres may help to guide more efficient management of CO₂ applications in tomato greenhouses. Leaf starch and LMA (leaf mass per unit area) were investigated in commercially grown greenhouse tomato plants to determine the distribution and influence of leaf area and fruit load on these measures.     

Pome fruit viruses at the Canadian Clonal Genebank and molecular characterization of Apple chlorotic leaf spot virus isolates

A survey for apple and pear viruses was carried out at the Canadian Clonal Genebank (CCG), Harrow, Ontario, Canada, during the fall/winter of 2007 and spring of 2008. Leaves and/or dormant cuttings were randomly collected from 438 to 122 accessions of apple and pear, respectively. Samples were tested by Double Antibody Sandwich-Enzyme Linked Immunosorbent Assay (DAS-ELISA) for the presence of Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV) and Apple mosaic virus (ApMV). Infection rates for apples were ACLSV (48.1%), ASGV (10%), ASPV (6.6%) and ApMV (7.1%), and for pears ACLSV (42.6%). ACLSV was detected and characterization by multiplex RT-PCR with primers targeting a fragment of 677 bp corresponding to the partial coat protein (CP), movement protein (MP) and untranslated (3′UTR) region in 22 accessions of apple and pear. Multiplex RT-PCR showed a higher sensitivity over the ELISA test. The nucleotide and amino acid deduced partial CP identities ranged from 82.6–100% to 91–100%, respectively, while partial MP identities was 62.5–100% at aa level based on the amplified fragment appropriate for partial MP using a frame shift, among 22 ACLSV isolates. Phylogenetic analyses based on the partial CP region clustered CCG ACLSV isolates in two different groups, while those based on the partial MP region embraced CCG ACLSV isolates in two sub-clusters within the same group. This is the first report on the detection of ACLSV, ASPV, ASGV and ApMV at CCG, and the molecular characterization of ACLSV isolates in apple and pear plants from worldwide countries to deduce possible heterogeneity and evolution.     

Effect of tree and branch thinning on growth,yield, and fruit quality of persimmon trees in a high-density orchard

A study was conducted to evaluate the effect of branch and tree thinning on growth, yield and fruit quality in 8-year-old non-astringent persimmon (Diospyros kaki L.f.) trees in a high-density orchard over 6 years in Korea. Adjacent trees in the rows were removed in 2008 (first-year thinning) or in 2010 (gradual thinning). Trees in the second treatment also had 25% of the main scaffold branches removed in the first two seasons. Control plots were left unthinned. First-year thinning elevated leaf macro-nutrient concentrations, increased the production of short fruiting shoots (less than 20 cm) per tree, decreased water sprout development and weight of pruned biomass, and increased fruit set compared with values recorded on control trees and with gradual thinning. First-year thinning gave higher photosynthetic photon flux in the centre of the canopy and better fruit quality. There were generally only small differences in total yield across the three treatments in individual years, but much higher total marketable yield from 2010 to 2013 in the first-year thinning plots. First-year thinning improved overall tree productivity, and the gross returns were 80% higher than those of control from 2008 to 2013 when the extra cost of the thinning was taken into account.     

GA3 increases fruit weight in ‘Yu Her Pau’ litchi

In order to increase the fruit weight of a shriveled-seed cultivar, trees of ‘Yu Her Pau’ litchi (Litchi chinensis Sonn.) growing in Taiwan were sprayed with Gibberellic acid (GA₃) (ProGibb^®, 20% of GA₃) at 5 and 10 mg/l 14 days after full bloom (AFB) over 2 years. Both concentrations of GA₃ significantly increased fruit longitudinal and transversal diameter, and fruit, aril and pericarp weight (40–41 and 37–38 mm, and 27.3–28.4, 21.7–22.7 and 5.0–5.3 g, respectively) compared with control (35–36 and 33–34 mm, and 22.3–22.4, 17.8–17.9 and 3.9–4.0 g), but had no significant effects on seed weight, percentage of aril weight of total fruit weight or total soluble solids (0.5–0.7 g, 78.9–80.3% and 18.1–19.0 °Brix, respectively). Fruit characteristics within the two concentrations of GA₃ showed no significant difference. The results indicated that sprays of GA₃ should be evaluated in ‘Yu Her Pau’ commercial orchards, and in other elite cultivars.