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Abstract

Limbs of ‘Miller Sturdeespur Delicious’ apple trees (Malus domestica Borkh.) with bearing spurs ranging in age from 2 to 11 years were provided with differing solar exposure levels ranging from 5% to 95% of full sunlight (400 to 700 nm) from 55 days postbloom until harvest. As the exposure level of the limb canopy was reduced, fruit length, width, weight, soluble solids, starch content, and total solids were reduced while fruit firmness and total acidity were increased. Visual fruit red color of this high-coloring strain was not affected. As spur age increased, fruit length, width, weight, and soluble solids decreased while fruit firmness and total acidity increased. Spur age did not influence fruit red color, starch content, or total solids. Light exposure level accounted for a relatively large portion of the variation in fruit size and quality between limbs while spur age accounted for only a small portion of the variation within each limb.

Open Access

Abstract

(2-Chloroethyl)phosphonic acid (ethephon), 200 ppm, and naphthaleneacetic acid (NAA), 350 ppm, sprayed on fruitlets 1 cm in diameter, caused satisfactory thinning of heavily loaded ‘Wilking’ mandarin trees (Citrus reticulata Blanco) without significant decrease of yield in kg per tree. Individual fruit size was increased 64% with ethephon and by 48% with NAA, increasing profit by about 30% in both cases as compared with hand thinned controls. A summer pruning treatment had similar effects but the increase in fruit size was smaller. Ethephon reduced alternation of bearing and resulted in satisfactory yields the following year on 57% of the treated trees.

Open Access

`Feicheng' peach is a favorite cultivar in China due to is large size and high eating quality. However, its storage quality is poor and its market life is relatively short. Different combinations of AVG and GA3 applied at various stages of fruit development were evaluated to prolong market life of this fruit. A combination of 80-100 mg/L AVG and 80-100 mg/L GA3 at the end of pit hardening gave the best results. This treatment retarded the change in ground color, loss of firmness, and reduction in acidity by2 to 3 weeks. Since harvest was delayed, soluble solid content increased compared with the control that was harvested earlier. Fruit size increased significantly on treated trees. During 6 weeks of storage at 0 °C, ethylene evolution increased and fruit firmness decreased slowly in control fruit, but in AVG+GA3-treated fruit, they did not change from the low initial levels. At the end of storage, control fruit developed a high percentage (83%) of tissue browning and mealiness after warming at 20 °C for 4 days, but the AVG+GA3-treated fruit ripened normally and developed much less (16%) tissue browning and mealiness. Our results showed that the market life of `Feicheng' peaches can be prolonged by at least 4 weeks by using the AVG+GA3 treatment to delay harvest and improve storage quality.

Free access

Yield, fruit quality parameters and pruning costs were compared among differentially-pruned, mature navel orange trees planted at a density of 222 trees per hectare (90 trees per acre) in 2000, 2001 and 2002. The experiment was designed as a replicated, split block with topping height as the main plot split by three levels of interior pruning as subplots. A tree was reduced in height by mechanical topping to 4.3 m, 4.9 m or left untopped and hand pruned according to one of the three following options: 1. scaffold removal in March of 2000 followed by dead-brushing in 2001, and 2002; 2. dead-brushing only in 2000, 2001, and 2002; or 3. no topping or dead-brushing. Scaffold removal resulted in removal of approximately 50% of the tree canopy. Data were collected from experimental trees surrounded by similarly topped and interiorly pruned border trees. A highly significant positive-linear correlation (r 2 = 0.95) was found between the total numbers of fruit produced annually per hectare versus the total number of fruit sized 72 to 88 mm in diameter (i.e. fruit sized such that 88 to 48 may be packed in a standard 17-kg packing carton). This functional relationship existed whether reductions in fruit numbers were the result of severe pruning in March or from, apparently, weather-related year to year variability in fruit set. These results suggest that anything in this orchard that reduces fruit numbers below approximately 250,000 fruit per hectare at harvest (100,000 per acre) will result in a mathematically predictable decrease in the total number of harvested fruit sized 72 to 88 mm in diameter. Trees that were not topped and which had no interior pruning produced the largest number of valuable fruit without additional pruning costs.

Free access

Abstract

Different growth habits in the same genetic background were produced by backcross programs to obtain determinate, sp, indeterminate, sp +, jointless, j, and dwarf, d, forms of each of 3 varieties, ‘Gardener,’ ‘Fireball,’ and ‘Cornell 54-149.’ Compared at 2 spacings, 6 × 1.5 ft and 6 × 0.5 ft, indeterminate and jointless plants had larger fruit and higher soluble solids than determinate plants in all varietal backgrounds and at both spacings. The magnitude of the differences varied with varietal background. Dwarf plants produced smaller fruit than non-dwarf plants but with no difference in soluble solids. Closer plant spacings within the row resulted in both smaller size and decreased soluble solids of fruit.

Open Access

Heirloom tomato production is increasing in the Eastern United states as consumer demand increases. Pruning and suckering heirloom tomatoes have not been studied to see if there is any need for this labor-intensive activity. A 2-year study was undertaken to evaluate whether pruning or suckering would affect yield or fruit size for two heirloom cultivars (`Mortgage Lifter' and `Prudens Purple'). The treatments imposed on the cultivars were 1) removing all suckers from the second or third stem down after the flower cluster; 2) removing the bottom two suckers, or 3) removing no suckers. Pruning had no effect on early yield or fruit size (harvests 1–4). Mid-season (harvests 5–7) total and marketable yields were significantly higher for removing two suckers or not suckering over the other two treatments for year 1, but not year 2. The tomato fruit size was only reduced for the non-suckering treatment. There were no statistical differences among the pruning treatments for yield or fruit size for late season harvests (8-10) for both years. Marketable yields were statistically higher for no suckering over the two- and three-stem treatments, but not different from two suckers when all harvests were combined for the season for year 1. No statistical differences were observed in year 2. However, fruit size was reduced when not suckering compared to the other treatments. The cultivar `Prudens Purple' did have higher total and marketable yield than `Mortgage Lifter' for both early and total combined harvests, but not for mid- or late-season harvests in year 1. There were no statistical differences between the two cultivars for year 2.

Free access

The interaction between irrigation and crop load with respect to fruit size distribution was investigated in a `Golden Delicious' apple (Malus domestica Borkh) orchard located in a semi-arid zone. Irrigation levels during the main fruit expansion phase ranged from 0.42 to 1.06 of the Class A pan evaporation coefficient. Crop load was adjusted to 100 to 450 fruit/tree in the 1250 trees/ha orchard by hand thinning. Total yield was not affected by irrigation level up to a crop load of 200 fruit/tree. Yield of all grades >65 mm was affected by irrigation level for higher crop densities. The yield of fruit of diameter <75 mm was not affected by increasing the Class A pan evaporation coefficient above 0.75. Our data indicate that availability of assimilates may limit the size of fruit with potential to grow larger than 70 mm in diameter at all crop loads higher than 200 fruit/tree. This limitation increases with decreasing irrigation level. The volumetric relative growth rate (VRGR) increased with irrigation level and with decreasing crop load. VRGR was more affected by crop load than by irrigation level in the ranges studied.

Free access

Abstract

The effects of replanting stand-deficient plots on marketable tomato (Lycopersicon esculentum Mill.) fruit size and yields were investigated at Bradenton, Fla. during the 1986 spring and fall seasons. Treatments consisted of a control (10-plant plot) and plots with 9, 8, and 7 (10%, 20%, and 30%) missing plants. Other plots with the same stand deficiency were replanted to attain a complete stand 2 or 3 weeks and 1, 2, or 3 weeks after initial transplanting in the spring and fall experiments, respectively. Plots with 30% stand reduction produced a lower weight and number of marketable fruit per hectare than control plots in both seasons. In spring, replanting stand-deficient plots did not increase marketable fruit yields relative to plots not replanted, regardless of the time of replanting or percentage of stand reduction. In fall, under an unfavorable environment due to a late infestation of bacterial spot, replanting plots with 30% stand reduction increased marketable fruit yields over similar plots that were not replanted, when the replanting occurred 1 or 2 weeks after initial transplanting, but not when replanting was delayed 3 weeks. Small, medium, or extra-large marketable fruit weight per hectare were similar in both seasons for plots with 30% stand reduction, whether replanted or not. Mean fruit size (g/fruit) did not differ significantly among treatments in either experiment. These results suggest that replanting improved marketable tomato yields only when the level of stand deficiency reached 30% and only in a stressed environment.

Open Access

Abstract

Genetic and environmental components of variance were estimated in 2 seedling populations of plum and prune at the University of California, Davis, California; the first population comprised 90 progeny of 14 open-pollinated parents, the second, 430 progeny of 50 controlled crosses among 28 parents. The estimates of phenotypic and genotypic variability associated with these traits in these 2 populations were nearly identical. Heritabilities, estimated by regressing the 500 progeny from the second population on their 50 mid-parents, were very high (0.80–1.0) for fruit size measurements and ripening dates, but zero for fruit yield. Also high (0.49) was the maximum heritability of percent soluble solids, estimated by the genetic variance/phenotypic variance. Phenotypic correlations among the traits fruit size, ripening date, and percent soluble solids are also small but significant in this seedling population. These results indicated that the rates of gain to be expected from mass selection on such populations are substantial.

Open Access
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Abstract

‘Marsh’ grapefruit (Citrus paradisi Macf.) trees 32 years old, 5.1 m tall and 6.6 m wide were pruned with 5 methods: 1) light −4.5 m tall and 5.4 m wide; 2) moderate −3.6 m tall and 4.5 m wide; 3) severe −2.1 m tall and 2.4 m wide to main scaffolds (buckhorned); 4) Low-High – severe pruning of lower 1.8 m followed by severe pruning of upper part 3 and 5 years later; 5) control – deadwood removed. Yields, fruit size and grade and trunk growth were obtained for 6 years after pruning.

In the 1st year, yields and US No. 1 grade decreased, fruit size and trunk growth increased as the amount of fruiting wood removed became greater. No fruit was set on severely pruned trees. In the 2nd year yields on the lightly pruned trees were similar to the control. Moderately and severely pruned trees had normal yields in the 4th year. Thereafter, severely pruned trees produced more US No. 1 grade fruit which was slightly larger than fruit on the control trees. 6 years after pruning the severely pruned trees were 4.6m high and 5.2 m wide whereas the unpruned trees were 5.7 m and 7.3 m.

Open Access