Search Results

You are looking at 51 - 60 of 5,117 items for :

Clear All

We established a cladode load and thinning time that maximized fruit and flesh size in `Gialla' cactus pear (Opuntia ficus-indica Mill.). Five weeks after spring flush removal, second flush flower buds were thinned to nine, six, or three per cladode; the same treatment was repeated during the early stages of fruit development. Control cladodes had a natural load of 15 fruit. Time of thinning did not affect fruit growth and ultimate weight. Fruit and flesh weight increased with thinning, but export weight was obtained only in cladodes with no more than six fruit. Heavier thinning did not result in any further increase of fruit or flesh weight. Percent flesh was not affected by thinning. Fruit characteristics, such as total soluble solids concentration and seed content did not change with thinning, but the seeds: flesh ratio decreased with thinning. Fruit on cladodes with the lowest load ripened earlier than those on more heavily yielding cladodes.

Free access
Author:

To investigate the relationship between cell size and sugar accumulation, fruit of the melon was heated during the early stage of the growing period. The minimum air temperature in the heating apparatus was ≈10 °C higher than the ambient air temperature, and the weight of the heated fruit was greater than that of the control fruit. The number of rectangular parallelepiped (7-mm-long sample serially collected beginning at one end of the 10-mm-wide strip removed from the 10-mm-thick disk at the maximum transverse diameter of the fruit to the opposite end) with cells larger than 200 μm in the heated fruit at 17 days after anthesis (DAA, the end of heating treatment) was much larger that of the control fruit. The mean cell size in the heated fruit at 17 DAA was larger than that of the control fruit. Mean sucrose content of the heated fruit on 40 DAA was larger than the level in the control fruit. Higher fruit temperatures in melons covered with heating apparatus results in the predominance of larger cells and increased accumulation of sucrose in the fruit.

Free access

Abstract

Whole-tree sprays of gibberellic acid (GA) plus calcium dihydrophosphate Ca(H2PO4)2 increased fruit set of navel orange [Citrus sinensis (L.) Osb.] during 1979 and 1980. Gibberellic acid alone or a combination with Ca(H2PO4)2 or 6-benzylamino purine (BA) increased fruit set in 1980. Benzylamino purine did not increase fruit set or the fruit-setting effectiveness of GA. Calcium dihydrophosphate increased fruit set for approximately 5.5 weeks in 1980 even though leaves did not show signs of calcium deficiency. However, no increase in fruit set was observed 8.5 weeks after application. Fruit sprayed with GA were smaller than untreated fruit initially; however, no size differences were noted 8.5 weeks after full bloom.

Open Access

Experiments were conducted in 1989 to determine the heritability of shortened fruit maturation (SFM) period in 871213-1, an inbred cherry tomato line (Lycopersicon esculentum var. cerasiforme (Dunal.) A. Gray), and to determine the relationship between this trait and fruit size. In the first study, a cross was made between 871213-1 and NC 21C-1, an inbred cherry line. NC 21C-1 had a mean maturation period of 40.8 days compared to 32.0 days for 871213-1. A mean maturation period for the F1 hybrid of 32.9 days and 32.2 days was found using 871213-1 as the female and male parent, respectively. Analysis of the data from parental, F1, F2 and backcross generations yielded estimates of broad-sense and narrow-sense heritabilities for SFM as 0.72 and 0.56, respectively. Further analysis indicated that genetic control of SFM was quantitative in nature and highly dominant. A test for epistatic interaction showed significance. In the second study, an F2 population from the cross 871213-1 x NC 309-1, a large-fruited tomato line (Lycopersicon esculentum Mill.), was evaluated to determine if any correlations existed between fruit size and SFM. Two fruit characteristics, locule number and fruit weight, were used as estimates of fruit size. Correlations between SFM and these two characteristics were +0.28 and +0.61, respectively. Broad-sense heritability of SFM was estimated as 0.64.

Free access

The effects of low and high crop loads in 2002 on floral development (Summer 2002), pistil size at anthesis (Spring 2003), and subsequent season fruit size at maturity (Summer 2003) were studied. Trees were all thinned to the same crop load in 2003. Three peach cultivars (Elegant Lady, O'Henry and Fairtime) with different ripening times (mid-July, mid-August, and early-September, respectively) were used to assess the effects of current season crop on floral development for the subsequent season. Based on previous literature, we reasoned that the maximum competition for carbohydrates between maturing fruit and developing buds is likely to occur at fruit maturity, especially under heavy crop loads. In 2003, individual fruit were harvested and weighed at maturity. In all three cultivars, a heavy crop load reduced the percentage of floral buds initiated and delayed floral differentiation. A heavy crop load also reduced pistil size at anthesis and fruit size at maturity in the subsequent season. These data support the practice of vigorous pruning to annually renew fruiting wood in peach to minimize the influence of crop in the previous season on the subsequent season's fruit and maintain large fruit sizes.

Free access
Author:

Effects of chemical thinners on yield, fruit size, and fruit quality was studied in a commercial orchard in Milton, N.Y., on 6-year-old `Honeycrisp'/M.26 trees. The trees were planted at 1.8 × 3.6-m spacing with trickle irrigation and were trained to the vertical axis system. The treatments applied in a randomized complete-block design with four replications were an untreated control; carbaryl (Sevin XLR at 125 mL/100 L); NAA at 2.5 ppm, 5 ppm, or 7.5 ppm; NAA at 2.5 or 5 ppm plus carbaryl; and Accel (a.i. at 74 g·ha-1) plus carbaryl. Chemical thinners were applied to drip with an air-blast sprayer, when the largest fruit were 11.5 mm in diameter. Generally, thinning activity increased with increasing NAA concentration. The combination sprays of 5 ppm NAA plus carbaryl, and Accel plus carbaryl over-thinned `Honeycrisp'. Carbaryl alone was inconsistent. All thinning treatments increased fruit size relative to unthinned trees, with average fruit diameter exceeding 76 mm. `Honeycrisp' is a large-fruited cultivar that is easy to thin chemically at the traditional 10- to 12-mm growth stage. NAA at 2.5 or 5 ppm provided adequate thinning to produce fruit of good quality and size. If initial set is heavy and a stronger thinning response is desired, the combination of 2.5 ppm NAA plus carbaryl could be used. `Honeycrisp' appears to be very sensitive to Accel, when used in combination with Sevin XLR. Further research needed before Accel is used to thin `Honeycrisp'.

Free access

Abstract

Differential fruit thinning treatments produced differences in yield, fruit numbers, and fruit size in 2 ‘McIntosh’ and 1 ‘Empire’ apple (Malus domestica Borkh.) orchards. Fruit set, crop load, and fruit size data calculated from branch samples paralleled corresponding data for whole trees.

Open Access

Juice quality of `Valencia' sweet orange [Citrus sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks was determined for fruit harvested by canopy quadrant and separated into size categories to ascertain the direct role of rootstock selection on juice soluble solids concentration (SSC) and soluble solids (SS) production per tree of citrus fruit. SS production per fruit and per tree for each size category was calculated. Juice quality was dependent on rootstock selection and fruit size, but independent of canopy quadrant. Fruit from trees on Carrizo citrange had >20% higher SSCs than fruit from trees on rough lemon, even for fruit of the same size. Large fruit accumulated more SS per fruit than smaller fruit, despite lower juice content and SSC. Within rootstocks, SS content per fruit decreased with decreasing fruit size, even though SSC increased. Rootstock effect on juice quality was a direct rather than an indirect one mediated through differences in fruit size. The conventional interpretation of juice quality data that differences in SSC among treatments, e.g., rootstocks or irrigation levels, or fruit size, are due to “dilution” of SS as a result of differences in fruit size and, hence, juice volume, is only partly supported by these data. Rather, accumulation of SS was greater for fruit from trees on Carrizo citrange than rough lemon by 25% to 30%.

Free access

Many commercially grown stone fruit including apricots (Prunus armeniaca L.), peaches and nectarines [P. persica (L.) Batsch], plums (P. salicina Lindl., P. domestica L.), prunes (P. domestica L.), and pluots (P. salicina × P. armeniaca) have a tendency to produce high numbers of flowers. These flowers often set and produce more fruit than trees can adequately size to meet market standards. When excessive fruit set occurs, removal of fruit by hand thinning is necessary in most Prunus L. species to ensure that remaining fruit attain marketable size and reduce biennial bearing. Over the years there have been numerous attempts to find chemical or physical techniques that would help to reduce the costs associated with and improve efficiencies of hand thinning, however, alternate strategies to hand thinning have not been widely adopted for stone fruit production. In the past 10 years, several chemical treatments have shown promise for reducing hand thinning needs in stone fruit. Management of flowering by chemically reducing the number of flowers has been particularly promising on stone fruit in the Sacramento and San Joaquin Valleys of California. Gibberellins (GAs) applied during May through July, have reduced flowering in the following season in many stone fruit cultivars without affecting percentage of flowers producing fruit. As a result, fruit numbers are reduced, the need for hand thinning is reduced and in some cases eliminated, and better quality fruit are produced. There are risks associated with reducing flower number before climatic conditions during bloom or final fruit set are known. However, given the changes in labor costs and market demands, the benefits may outweigh the risks. This paper reviews relevant literature on thinning of stone fruit by gibberellins, and summarizes research reports of fruit thinning with GAs conducted between 1987 and the present in California. The term thin or chemically thin with regard to the action of GA on floral buds is used in this paper, consistent with the literature, although the authors recognize that the action of GA is primarily to inhibit the initiation of floral apices, rather than reduce the number of preformed flowers. At relatively high concentrations, GA may also kill floral buds. Chemical names used: gibberellic acid, potassium gibberellate.

Full access

Endothall (mono-N,N-dimethylalkylamine salt, 15.9%, endothallic acid 3.8%), ammonium thiosulfate (ATS, 55%), and Wilthin (1-aminomethanamide dihydrogen tetraoxosulfate, 79%) were evaluated over 3 years for use as blossom thinners on mature `Garnet Beauty' and `Red Haven' peaches (Prunus persica). Endothall and ATS were the most effective blossom thinners and reduced set in all 3 years. Wilthin reduced initial set in 2 of 3 years. Hand thinning was reduced by 50% to 80% on endothall and ATS treated trees. The reduction in crop load at bloom resulted in significant increases in fruit size at harvest. We suggest the use of ATS at a rate of 35 to 45 L·ha-1 (3.5 to 5 gal/acre) and endothall at 1.8 L·ha-1 (1.5 pt/acre), applied in 935 L·ha-1 (100 gal/acre) on mature trees. The use of Wilthin at rates higher than 18.6 L·ha-1 (8 qt/acre) may be required for adequate thinning, but phytotoxicity at higher rates was not tested. Other important components for successful blossom thinning include applying materials before the majority of flowers have been pollinated (slightly before full bloom) and to apply the spray when there is very littlewind to assure good coverage and to prevent localized areas displaying increased phytotoxicity.

Full access