Large-fruited Cultivars Research Articles

270 Effects of Chemical Thinners on Yield, Fruit Size, and Fruit Quality of `Honeycrisp' Apple

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'.

Carbohydrate content and the activities of sucrose synthase, sucrose phosphate synthase and acid invertase in different tomato cultivars during fruit development

Changes in carbohydrate content and activities of related enzymes of the developing fruits of three tomato cultivars ( Lycopersicon esculentum Mill. cv. Momotaro, Lady First and Minicarol) were followed throughout fruit development. In all the cultivars fructose and glucose in nearly equal amounts, were the predominant sugars. Sucrose was present in trace quantities but the small fruited cultivar Minicarol accumulated higher levels of sucrose than the other two large fruited cultivars. The activity of soluble acid invertase (EC3.2.1.26) was highest in ripe fruits (55 days of anthesis) but in the case of cell wall-bound acid invertase, it was less and almost constant throughout development. Sucrose synthase (EC2.4.1.13) activity was highest in the young fruit and declined sharply with development; ‘Minicarol’ had the highest activity. Sucrose phosphate synthase (EC2.4.1.14) activity remained relatively constant throughout development in all cultivars studied. A highly significant positive correlation was found with sucrose accumulation in the case of sucrose synthase but there was a negative correlation with acid invertase activity and none with sucrose phosphate synthase. Therefore, it appeared that acid invertase and sucrose synthase were involved in the metabolism of sucrose during tomato fruit development and a constant sucrose phosphate synthase activity was not required for sucrose accumulation. Furthermore, the small fruited tomatoes had a higher amount of reducing sugars and sucrose, and higher sucrose synthase and sucrose phosphate synthase activities compared with large fruited types. The results are discussed in terms of the metabolic events associated with soluble sugar accumulation.

Differences in Number and Area of Mesocarp Cells between Small- and Large-fruited Peach Cultivars

The growth in diameter of large-(`Loring' and `Suncrest') and small-fruited (`Bailey' and `Boone County') peaches [Prunus persica (L.) Batsch] was recorded at weekly intervals from 175 days prebloom to ripening. Samples collected at three dates prebloom, full bloom (FB), and four dates postbloom, including ripe fruit, were sectioned and stained. Total cell count and mean cell size were determined for prebloom ovaries and postbloom mesocarp tissue. Large-fruited cultivars had significantly more cells (up to 3.7 times) than small-fruited cultivars at all sampling dates. Cell sizes increased dramatically with fruit development, but were similar for all cultivars within each sampling date. These results suggest that mesocarp cell count is the major difference between small- and large-fruited peach cultivars and that this difference is determined early in the growth of the ovary.

Effect of Harvest Maturity on the Final Fruit Composition of Cherry and Large-fruited Tomato Cultivars

Abstract Fruit of 2 cherry tomato (Lycopersicon esculentum var. cerasiforme Alef.) cultivars [‘Large Red Cherry’ (‘LRC’) and ‘Small Fry’ (‘SF’)] and 2 large-fruited tomato (Lycopersicon esculentum Mill.) cultivars (‘Duke’ and ‘Sunny’) were harvested green, ripened at 23°C, and analyzed for sugars and organic acids 6 days after breaker stage. Both fructose and glucose concentration decreased in ‘LRC’ and ‘SF’ fruit with less-mature harvested fruit. Maturity at harvest had no effect on the concentration of either sugar in ‘Duke’ or ‘Sunny’ fruit. ‘LRC’ had the highest fructose and glucose concentration among cultivars. Increased citric acid concentration was found with less-mature harvested fruit, except in ‘LRC’. Malic acid concentration within cultivars was similar in the fruit harvested more mature, but decreased with less-mature fruit in ‘Duke’ and ‘Sunny’. ‘LRC’ and ‘SF’ fruit had more citric and malic acid than ‘Duke’ or ‘Sunny’. Cherry tomato cultivars had a higher percentage of locular tissue than the large-fruited cultivars.

Deriyation of the Binomial Fragaria ⨯ ananassa for the Cultivated Strawberry1

Abstract Although strawberry species have existed for an estimated 50 million years (17), and their use by man has been dated to the bronze age (19), only after the 14th century A.D. were strawberry plants gathered from the wild and grown in gardens. These first cultivated strawberry plants were grown for both ornamental and medicinal purposes (11). The strawberries of the past were different from those of today. The fruit was small, plants were not productive, and in many respects were far inferior to the large fruited cultivars that are now grown in many parts of the world.

Effect of Tomato Cultivars on Insect Damage and Chemical Control

`Pennorange E160A' and `Pearson' tomatoes had fewer fruit damaged by Keiferia lycopersicella (Wals.), the tomato pinworm, and armyworms, primarily Spodoptera eridania (Cramer), the southern armyworm, in 2 tests than on `Walter.' When measured by the number of damaged fruit, the degree of control of the tomato pinworm and southern armyworm with Dipel WP and chlordimeform was significantly affected by tomato cultivar. The number of Liriomyza sativae Blanchard leafmines/10 trifoliates (3 terminal leaflets) was significantly less on UF-763292 (a pubescent mutant breeding line), `Earliana,' `Pennorange E160A' (a cherry tomato), `Pearson,' and `Pritchard' tomato cultivars in 2 tests. Despite significantly more insect damage, `Walter' yielded more than other cultivars, primarily because of less loss from graywall. No large fruited cultivar offered much potential as a replacement for `Walter' in areas where populations of tomato pinworm, armyworms, and leafminers occur annually. `Pennorange E160A' may offer an alternative for home garden use and large, fresh market tomatoes in areas where insects are damaging in most seasons. The multiple resistance of `Pennorange E160A' and `Pearson' to the tomato pinworm, armyworms and the vegetable leafminer may be of benefit in a breeding program.

COMBINING ABILITY ANALYSIS AND INTERRELATIONSHIPS BETWEEN THORNINESS AND YIELD TRAITS IN GOOSEBERRY

Combining ability and interrelationships among four characters were studied in six gooseberry (Ribes grossularia) progenies produced by crossing each of two thornless to three large-fruited cultivars. Measurements were recorded for four consecutive years for fruit yield and 100-berry weight, and for one year for thorniness and plant height. General and specific combining abilities were significant and their interactions with years were not significant for fruit yield and berry weight, and general combining ability was significant for thorniness. Genotypic correlations agreed closely with the phenotypic correlations. Significant positive correlations were obtained between fruit yield with berry weight and plant height. The nonsignificant correlations between thorniness with fruit yield, berry weight and plant height suggest no genetic barrier to combining thornlessness with these traits.

Fruit and pedicel characters derived from Galápagos Tomatoes’

By relatively simple breeding procedures, seven different modifications of fruit and pedicel have been successfully transferred from wild tomatoes of the Galapagos Islands to large-fruited cultivars. Some of these traits, the majority of which are simply inherited, may have horticultural value. Such introgression from the wild forms is expedited by the remarkable freedom from barriers at any stage of the breeding processes.