Loquat fruit size is increased through the thinning effect of naphthaleneacetic acid

The thinning effect of naphthaleneaceticacid was examined in loquat trees (Eriobotryajaponica Lindl.). The effect depended on theconcentration applied and on the treatment date. Themost effective treatment found to thin fruit andincrease the average fruit size was the application of20 mg l^–1 of naphthaleneacetic acid 10–15 daysafter anthesis. Treatment reduced the fruit resistanceto puncturing and improved total soluble solidsconcentration and coloration and, consequently,harvest time was markedly advanced.     

The allometry of the weight of fruit on trees and shrubs in Barbados

Summary Branch sampling of branch diameter and fruit crop on 22 species of Barbadian trees and shrubs provided sufficient data to build regressions between plant size and fruit crop weight. Orchard plants bear much more fruit than wild, feral or garden plants of similar size, but this difference disappears in multiple regression of fruit crop weight (F in g, fresh mass) on branch or stem diameter (D in cm) and individual fruit weight (W in g): F=22D^1.2 W^0.57. This explains 89% of the variation in F and successfully predicts crop weight for wild tropical and temperate trees and shrubs, but underestimated the crops on commercial, temperate, fruit trees by an order of magnitude. Comparisons of crop weight for feral, wild, and garden plants (F_f) using a simple regression F_f=47D^1.9 show that crop weight is a minor load relative to branch weight for larger branches. Although fruit crops represent a declining proportion of total plant weight as plants become larger, the crops become larger relative to leaf and twig weight and in this sense, reproductive investment increases in larger plants. Finally, our equations, combined with the self-thinning rule, suggest that stands of large species of fruit plants produce more fruit per unit of land area than stands of small ones.     

Alleviation of frost damage to pear flowers by application of gibberellin

Adverse effects of gibberellin applications on pear trees after frost such as small fruit size, abnormal fruit shape and poor return bloom are often attributed both to the sole use of GA₃ and its overdose. It is unclear whether protection against spring frosts before flower opening is more efficient when GA is applied directly after frost, i.e. before flower opening, or at full bloom or both. In April 2003, early spring frosts at Klein-Altendorf near Bonn, Germany damaged ca. 88% flowers of the early flowering cv. Alexander Lucas, 64% of cv. Conference and ca. 25% of flowers of the later flowering cv. Comice pears. Hence, the objective of the present work was to investigate the optimum timing of the application of low doses of the combined GA₃ and GA_{4 + 7} to improve parthenocarpic fruit set in pears, while maximising fruit quality and size for trees affected by a severe spring frost before full bloom. Return bloom was also considered and quantified. Frost-affected pear trees were treated with gibberellin GA₃+GA_{4 + 7}, either immediately after the frost, at the white bud stage, or at full bloom or both to improve parthenocarpic set. Early flowering cv. Alexander Lucas pear was most affected by the early spring frost, but lost only 25% of fruitlets at June drop, irrespective of GA treatment. June drop was, however, severe in the two other cultivars least affected by frost, i.e. by 33% in cv. Conference and 55% in cv. Comice. Both initial and final fruit set were significantly increased by a combined application of GA₃+GA_{4 + 7} at full bloom, without affecting return bloom, but June drop was also enhanced by GA application. The largest positive effect of GA application on fruit yield, an additional 2 kg of fruit per tree equivalent to €1200/ha, was apparent with the cv. Alexander Lucas, i.e. the cultivar most affected by frost. There was no loss in fruit quality viz fruit size after any of the GA applications with any of the pear cultivars examined and no increase in abnormally-shaped, elongated fruit.     

Small fruit problem in Citrus trees

Summary Physiological causes of the small fruit problem which occurs in certain trees of orange [Citrus sinensis (L.) Osbeck cv. Valencia] were investigated in terms of water relations and gas exchange of fruits during early fruit development as well as tree carbohydrate reserves. These data from cv. Valencia trees with and without a small fruit potential were compared with those of the large fruited cv. Navel. Neither fruit water potential nor fruit transpiration nor tree carbohydrate reserves appeared to be a cause of the small fruit. Yield records showed the small fruit to be assocaited with a large number of fruit per tree. However, fruits from cv. Valencia trees with a small fruit potential respired faster than either fruits of the same cultivar and size from trees without the physiological disorder or fruits of the same size of cv. Navel and also exceeded the dark respiration of the respective leaves. Hence, the small fruit problem in cv. Valencia was partly attributed to inefficient fruit photosynthesis, causing excessive respiration of each of a larger number of fruits compared to fruits of a tree of the same cultivar but without the physiological disorder. Fruits of cv. Valencia respired more in their 2 months longer lifetime on the tree relative to those of cv. Navel. It is concluded that orchard management methods will have to be investigated to balance the fruit load of the cv. Valencia tree utilizing the carbon available for fruit growth and to minimise stress during the early fruit development.     

Strapping and a synthetic cytokinin promote cell enlargement in ‘Hiratanenashi’ Japanese persimmon

The effects of N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) with and without strapping on fruit growth of ‘Hiratanenashi’ Japanese persimmon were evaluated by measuring parenchyma cell size and the number of cell layers in mesocarp throughout fruit development. Three-year-old branches were strapped with a wire 2 weeks before full bloom, and 10 mg l⁻¹ of CPPU was applied to the fruitlet at 10 days after full bloom. CPPU alone prolonged the growth period, resulting in a larger fruit diameter at harvest than the control. Strapping promoted the fruit coloration and increased final fruit diameter. CPPU plus strapping shortened the growth period compared to CPPU alone, and the mature fruit diameter was similar to CPPU alone. The increases in fruit diameter caused by CPPU and strapping were involved with the increases in length of parenchyma cell. The number of cell layers was almost similar among the treatments. These results showed that strapping promotes the rate of parenchyma cell expansion, and CPPU with and without strapping prolong the duration of cell enlargement and promote the rate of the cell expansion.     

Influence of between-year variation in the density of Rhus <Emphasis Type="Italic">trichocarpa</Emphasis> fruits on the removal of fruit by birds

The fruiting phenology and fruit removal patterns of Rhus trichocarpa Miq. (Anacardiaceae) were investigated in a warm-temperate secondary forest in Japan. Mature fruits of this species are dispersed by birds. Effects of fruit display size and canopy openness on fruit removal were investigated in years with different fruit densities (i.e., masting and non-masting years). Moreover, effects of increased canopy openness during winter on fruit removal were also investigated. Seasonal patterns of fruit removal were quite different between masting and non- masting years. In the non-mast year, fruits were removed by birds soon after maturation in the summer. In contrast, in the mast year, fruits were removed gradually by birds from summer to winter. Moreover, the rate of fruit removal was greater for trees with a larger display size in the non-mast year, whereas that was greater for trees with greater canopy openness in the mast year. Canopy openness increased in winter, and fruit removal in winter was enhanced in trees with a more open canopy only in the non-mast year. These observations strongly suggest that avian dispersers became satiated in the mast year, whereas fruit removal was enhanced in the non-mast year. In the mast year, although many fruits were not dispersed until winter, they were neither depredated nor rotten, and the long period of fruit removal by birds may have enhanced fruit dispersal. The large abundance of seedlings and saplings of this species in Japanese secondary forests suggests that this fruiting strategy is beneficial.     

Facultative ripening in Hamelia patens (Rubiaceae): effects of fruit removal and rotting

Summary In Costa Rica individual Hamelia patens trees produce fruit throughout the year and experience dramatic changes in rates of fruit removal and rotting. During some moths, most fruits rot because they are not removed. Rotting fruits increase the probability that other fruits on the same infructescence will rot. When removal rates are high, fruits are taken as soon as their seeds become viable but before the fruit is completely ripe. Experimental removal of fruits produced significantly higher ripening rates than on control infructescences. This response allows Hamelia to ripen more fruit and increase the number of fruits taken when dispersers are abundant (e.g., during migration). The proximate mechanism of this response probably includes reallocation of energy conserved when partially ripe fruits are removed. Responding to fluctuating disperser populations likely increases dispersal success and may function as the ultimate cause.     

Fruit color and fruit size of bird-disseminated plants in Japan

Fruit color, fruit size and phenology of bird-disseminated plants were examined in different climatic zones of Japan and the relationships between the plants and frugivorous birds were disscussed.Black fruit was the most common in warm-temperate areas and red was the most common in cool-temperate and subarctic zones. Red was more dominant in the lower layer of the forests in all climatic zones. Bicolor fruits were frequent in trees and were not found in herbs. Both in warm- and cool-temperate zones conspicuous fruits which are red and bicolored display were more frequent in summer than in winter.The diameter of most fruits were 4–11 mm. Fruits in warm-temperate were somewhat bigger than those in cooltemperate zone. In forest strata the fruits of shrubs were smaller than those of trees and herbs in width. However I found no relationships between fruit size and fruit color.The frugivorous birds could have influenced not only the evolution of seasonal differences in the proportion of fruit color between warm-temperate and cool-temperate region, but also affect the fruit size.     

Foliar application of aminoethoxyvinylglycine (AVG) delays fruit ripening and reduces pre-harvest fruit drop and ethylene production of bagged “Kogetsu” apples

Covering apple fruits with double layer waterproof bags to enhance fruit quality and evenness of blush colour is typical on many cultivars in Korea and Japan. Aminoethoxyvinylglycine (AVG) applied to unbagged apple fruits at 3–4 weeks before commercial harvest reduces ethylene production in the fruit, delays fruit ripening and reduces pre-harvest fruit drop. Spray application of AVG to trees of bagged apples should have no effect on apple ripening as there is␣no direct contact with the fruit and the translocation of AVG in apple trees is regarded as negligible. However, preliminary experiments suggested that AVG applied to trees of bagged apples reduced pre-harvest fruit drop in “Kotgetsu” apples. This study investigated the effect of spray treatments of 125 ppm of AVG on fruit drop, fruit ripening (firmness, starch conversion and soluble solids) and ethylene production to whole trees with bagged or unbagged “Kogetsu” fruit, as well as sprays of only the bagged or unbagged fruit on trees on two orchards. AVG applied to whole trees with unbagged apples reduced fruit drop from an average of 58.9% to 10.4%, delayed starch conversion and decreased ethylene production. AVG applied to whole trees with bagged fruit was equally effective in reducing pre-harvest drop, delaying fruit ripening and reducing ethylene production. Application of AVG to unbagged fruit only was nearly as effective as application to whole trees with unbagged fruit but application to bagged fruit only had no effect on fruit ripening or ethylene production. Application of AVG to bagged fruit only did reduce fruit drop to an average of 42.5% but this was not as effective as spraying unbagged fruit only or whole trees with bagged fruit. Possible mechanisms for this effect are discussed.     

Vascular tissues development of citrus fruit peduncle is promoted by synthetic auxins

The application of synthetic auxins to entire trees of'Okitsu' Satsuma and 'Fortune' mandarins significantlyincreases fruit peduncle diameter. This effect is partially due to the increaseof fruit size promoted by the auxins, but is also due to a direct effect of thesynthetic auxins promoting the development of peduncle vascular tissues. Bothxylem and phloem development is affected by the auxins. This direct effect hasbeen shown by applying the auxins locally to the fruit or to the peduncle.     

Response of ‘Clausellina’ Satsuma mandarin to 3,5,6-trichloro-2-pirydiloxyacetic acid and fruitlet abscission

The application of the synthetic auxin 3,5,6-trichloro-2-piridyloxyacetic acid (3,5,6-TPA) isopropyl ester at the onset of cell enlargement stage, significantly thinned fruitlets in ‘Clausellina’ Satsuma mandarin. The magnitude of the response was related to the concentration applied, increasing the percentage of abscised fruit with higher concentrations, which was up to 70% at 25 mg l⁻¹. The magnitude of the response also depended on the organ subject to treatment, abscission being greater when applied to the leaves rather than to fruit. Results suggest that a photosynthetic disorder was responsible for a reduction in fruit growth rate, triggering abscission mechanisms producing ethylene and abscission.     

Lek Site Selection by Male Mediterranean Fruit Flies

The mating system of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is based on leks. In field cage choice experiments we examined lek site selection as influenced by the presence of fruit and the presence of conspecific flies. Males were allowed to choose between artificial trees containing fruit and trees without fruit. Males showed a significant preference for the tree baited with fruit. To determine which fruit-related stimuli were important, males were allowed to choose between visual and/or olfactory fruit-derived stimuli. Males preferred to lek on trees presenting both stimuli. To determine the influence of conspecifics on lek site selection, males were allowed to choose between trees containing male and/or female conspecific flies. The presence of pheromone-emitting males was preferred. In addition, both in the field and on artificial trees, we examined the effect of leaf size on lek site selection. In the field, males preferred to lek on leaves of a particular size. Moreover, leaf integrity was important, as males tended to select undamaged leaves as lek sites. In field cage experiments, males consistently chose to lek on trees containing the largest leaves. We conclude that the choice of lek site is influenced by the presence of fruit and of other lekking males, while leaf size and integrity determine male location within a lek.     

谷氨酸和TDZ对荔枝果皮着色及果实品质的影响

为提前或延迟果实的成熟,改善果实品质,以荔枝(Litchi chinensis Sonn.)早熟品种‘三月红’和‘水东’为试验材料,在盛花后50 d用谷氨酸(Glu)和TDZ(Thidiazuron)进行处理,研究Glu和TDZ对果皮着色和果实品质的影响。结果表明,Glu能促进果皮转红,500~1500 mg L-1范围内随浓度增加果皮红色面积加大,果皮的花青苷含量增加。1500 mg L-1Glu处理的‘三月红’‘、水东’果皮花青苷含量分别达到8.62 U g-1、11.53 U g-1,分别比对照高出1.33、1.25倍。同时,Glu处理能促进‘三月红’总糖的积累,但对两品种果实大小和质量的影响不大。TDZ显著迟滞果实着色,果实转红延后,果皮花青苷含量降低。5.0 mg L-1TDZ处理的‘三月红’‘、水东’果皮花青苷仅为1.23和3.4 U g-1,显著低于对照。TDZ处理两品种果实的可溶性固形物、总糖含量均下降,但果实大小和质量均增加。因此,Glu能促进荔枝果实转色成熟,TDZ则抑制果实转色。     

Resource patch size and flexible foraging in white-faced capuchins (Cebus capucinus)

White-faced capuchins (Cebus capucinus)on Barro Colorado Island, Panama, have a flexible foraging strategy. Typically, foraging party size is small and individuals feed dispersed from one another. When seasonal fruiting of large volume trees occurs, the majority of the group forages simultaneously. As C. capucinusdo not display a rigorous dominance structure and there are few indications that individuals or coalitions monopolize food patches,individuals are expected to display scramble strategies instead of high frequencies of contest competition. I recorded foraging party size (simultaneous foragers), the total number of animals to feed successively, and the diameter at breast height (DBH) of fruit trees used in two habituated troops. Individuals in each group spent a substantial amount of time — 65 and 48% of foraging time for each group — foraging in party sizes of one. Monkeys predominantly foraged alone in small trees (0- to 20- cm DBH), successively in medium trees (21- to 60- cm DBH), and simultaneously in large trees (>61- cm DBH). They used small trees more frequently than all other tree classes. In medium-sized trees, although fruit was plentiful, space was limited. In these trees Cebusforaged successively. In large-volume trees, space and fruit were abundant and several individuals fed together. As the DBH of fruiting trees increased, the average foraging party size increased exponentially. Cebus capucinusat Barro Colorado Island modify their foraging party size to adapt to the seasonal patterns of fruit production.     

The reduction of naringin content of grapefruit by applications of gibberellic acid

Four different plant growth regulators, gibberellic acid (GA₃), naphthaleneacetic acid (NAA), benzyladenine (BA) and abscisic acid (ABA), were individually mixed in a lanolin paste and applied to immature fruit on grapefruit trees beginning soon after fruit set. The treated fruit was allowed to mature on the tree. Application of 1000 ppm GA₃ in this manner generally increased fruit size, decreased the concentration of the total acid in the juice and decreased the concentration of naringin in the juice sacs compared to that of the controls. GA₃ increased the total soluble solids (brix) in the juice in some experiments. Treatment of fruit with 1000 ppm ABA and BA significantly decreased the size of the fruit and increased the naringin concentration, but had variable effects on the soluble solids content and the acid content. Treatment with 1000 ppm NAA did not produce any significant changes in size, acid content, brix or naringin concentration.RetiredReference to a company or product name does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of other products that may be suitable.     

Gradual increase in the number ofAsphondylia aucubae (Diptera,Cecidomyiidae) due to inversely density-dependent mortality processes

The population dynamics of the aucuba fruit midge,Asphondylia aucubae (Japanese name: Aokimitamabae), were studied for 3 yr mainly at a broad-leaved evergreen forest on Mt. Shiroyama in Kagoshima City. This species is univoltine and adults emerge in May. Eggs were laid randomly inside the immature fruit of the host plant,Aucuba japonica (Japanese name: Aoki). Healthy fruit fell by the following March, whereas galled fruit remained on the trees even after the emergence of adult midges. The survival rate from the egg to adult stage was estimated to be 24.2%, and the number of midges on five census trees increased gradually during the census period. Two important mortality factors were recognized, i.e., fall of incompletely galled fruit and damage of the galled fruit by feeding of caterpillars of a moth. Some unknown factors were also found to be important, operating in an inversely density-dependent manner. The gradual increase ofA. aucubae is considered to be caused by such inversely density-dependent mortality processes.     

Dynamics of nitrogen uptake and partitioning in early and late fruit ripening peach (Prunus persica) tree genotypes under a mediterranean climate

The dynamics of N uptake and N partitioning in peach (Prunus persica, Batsch) trees of a very early (cv. Flordastar) and a very late (cv. Tudia) fruit ripening varieties grown under a mediterranean climate was assessed during one season. Labelled N was applied to two-year old potted trees which were destructively harvested at regular intervals during the vegetative and reproductive cycle. Tree phenology as well as vegetative and reproductive growth of the two genotypes strongly differed: bud burst started in late January in Flordastar and late March in Tudia. Leaf senescence in Flordastar was almost complete by mid October, while Tudia still retained a significant fraction of leaves at the December harvest. Fruit yield averaged 4.0 and 6.9 kg tree^–1 (fresh weight) in cv. Flordastar and Tudia, respectively, and fruit size was within commercial standards for the two genotypes. After growth resumption, shoot and fruit growth mainly relied on N remobilised from reserves, which accounted for 72–80% of total N in new growth. Nitrogen uptake by both genotypes was relatively low in the first month after bud burst, then was more rapid until the end of the season. Total labelled N uptake did not differ between the two genotypes and accounted on average for 65–70% of total N supplied. The kinetics of labelled N uptake were similar in the two varieties despite the great difference in the timing of their fruit ripening. Leaves were the main sink for N during much of the experimental period. The fruits, when present, also used a significant fraction of the absorbed N, which was almost constant until fruit ripening in Flordastar. Nitrogen partitioning to leaves declined progressively after summer, when a greater fraction of the absorbed N was recovered in the twigs, the trunk, the fine roots and especially in the coarse roots. The data provide evidence for guiding the kinetics of N supply to peach orchards under a Mediterranean climate.     

Postplant Fumigation with DBCP for Citrus Nematode Control in Florida

Eleven citrus groves of diverse varieties and ages infected with Tylenchulus semipenetrans growing in differing soils in Florida were treated with three rates of 1,2-dibromo-3-chloropropane (DBCP) applied by various means. Yield, fruit size, and T. semipenetrans populations in the roots were compared between DBCP-treated and untreated trees over a period of I-3 yr. Maximum fruit size and yield were obtained by applying DBCP at 38-58 kg/hectare (ha) (34-52 lb/acre); whereas best nematode control was with a rate of 77 kg/ha (69 lb/acre). Application of chemical emulsion with a special, drilled, low-profile sprinkler irrigation ground pipe was the most suitable method. Effect of DBCP treatment generally lasted for 3 yr. A mean annual I. 1% increase in fruit diameter, 15.2% increase in fruit yield and a 55.7% decrease incitrus nematode populations was found for D BC P-treated trees in contrast to untreated trees.