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Abstract

‘TAMU Triple Cross’ is a three-way hybrid pickling cucumber (Cucumis sativus L.) developed for mechanical harvesting. It is the first American pickling-type hybrid cucumber developed from three inbreds. ‘TAMU Triple Cross’ exhibits several outstanding characteristics including high yield, desirable fruit shape, dark green color, excellent processing qualities both as brinestock and fresh pack, broad spectrum resistance to cucumber diseases, and finally, an improved and less expensive system for production of hybrid seed (1,2,3).

A field study was conducted on TG1015Y onions (Allium cepa L.) grown in the Lower Rio Grande Valley of Texas. Treatments included two soil types (clay & loam), four harvest dates throughout the bulbing process, and two S rates [0 kg S/ha (standard) & 22.4 kg S/ha (high)]. Laboratory analysis included pyruvic acid concentration for pungency measurement, percent dry matter, and sucrose, glucose, and fructose concentrations. Harvest date influenced all variables tested. Percent dry matter generally decreased as bulbs matured (8.0 to 6.9% DM) with a slight increase at maturity (7.4% DM). Enzymatically developed pyruvic acid concentrations ranged from 3.13 to 4.03 μmole/g fresh wt. There was an upward trend of pyruvic acid over the bulbing process. Total sugars, measured by HPLC methods, tended to increase during bulb development (39.3 to 46.5 mg/g fresh wt.). However, sucrose decreased during the last two harvests causing a corresponding increase in glucose and fructose. The S treatment had no effect on any of the factors measured. The only influence by soil type was sugar concentration, with the loam field being higher in glucose.

An `intermediate leaf' hybrid pickling cucumber (TAMU 884304 X ARK H-19 `little leaf') was direct-seeded at four plant densities (94,570; 48,440; 32,290; 25,375 plants/ha) using four within-row spacings (15, 30, 45, 60cm) at two locations and two seasons. Optimum yield based on marketable fruit number, grade distribution and fruit quality occurred with 94,570 plants/ha. Optimum harvest time depended on location and season. Delayed harvest times were also evaluated. Harvests with fruit >5.1cm in diameter had severely reduced brining quality. Fruit did not enlarge or enlarged slowly to oversize. This resulted in a mixture of fruit ages within the largest marketable fruit grades. It is recommended that `little leaf' lines and their hybrids such as `intermediate leaf' be harvested when fruit 3.8 to 5.1cm in diameter appear and before oversize fruit are produced. Spacing did not significantly effect length/diameter ratio(LDR) but LDR was significantly greater for delayed harvests.

Abstract

Two gynoecious inbred lines of cucumber, ‘Gy 3’ and ‘MSU 35G’ their hybrids with the hermaphroditic ‘TAMU 950’ and backcrosses of the hybrids to their respective gynoecious parents were treated with gibberellin to test the phenotypic stability of gynoecism. Hybridization with ‘TAMU 950’ stabilized the gynoecious character and gibberellin A₄/A₇ provided a good test of stability.

Abstract

A true hermaphrodite cucumber was derived from the andromonoecious cultivar ‘Crystal Apple’. Hybrids developed by using gynoecious lines and the hermaphrodite line, TAMU 950, were 100% gynoecious. Fruits produced on the hybrids were similar in size and shape to that of the gynoecious parent. Use of the hermaphrodite in the production of such totally gynoecious hybrids permits the blending of precise quantities of a monoecious pollinator with hybrid seed before planting. Production of 100% gynoecious hybrids in this manner make parthenocarpic hybrids feasible.

Abstract

Microscopic observations revealed that the epidermal layer of fruit of MSU 35G (warty) was composed of cells whose longest axis were perpendicular to the fruit surface and about 50 µ thick. The epidermal layer of fruit of MSU 6902 (non-warty) was composed of cells approximately 20 µ thick with little elongation in either visible axis. The F₁ (warty) and warty fruit in the F₂ exhibited a cellular shape similar to the warty parent. However, the thickness of epidermal cells of these warty progency were significantly less than that of the warty parent when observed in cross-section. Epidermal cell thickness of warty fruit observed in cross-section became increasingly less as the percentage of MSU 6902 in the genetic background increased. Subepidermal cells of fruit with non-warty skin were larger than corresponding cells of warty fruit. The epidermal cell shape of MSU 6902 was linked with the non-warty characteristic. Epidermal cell thickness is inherited independently of epidermal cell shape.

Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the United States However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H₂O or hydrogen peroxide (H₂O₂). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of H₂O or H₂O₂; both nicking and H₂O₂ increased germination but not equal to rate of the control in 5 mL H₂O or H₂O₂. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (cv = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seed coat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.

Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the U.S. However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H₂O or hydrogen peroxide (H₂O₂). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of the H₂O or H₂O₂; both nicking and H₂O₂ increased germination, but not equal to rate of the control in 5 mL H₂O or H₂O₂. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (CV = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seedcoat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.

The ratio of individual sugar compositions is an important fruit quality trait in muskmelon. Our objective was to identify RAPD markers associated with QTL for percentage of each individual sugar (sucrose, glucose, and fructose) using bulked segregant analysis in an F₂ population derived from the melon cross of `TAM Dulce' (high sucrose percentage of total sugars) x TGR1551 (low sucrose percentage of total sugars). Continuous distributions for sucrose, glucose, and fructose percentages of total sugars were observed in the genetic population indicating quantitative inheritance for the traits. A significant positive correlation was observed between sucrose percentage and sucrose (r= 0.89) or soluble solids (r= 0.33), whereas a significant negative correlation was noted between sucrose percentage and glucose percentage (r = –0.85) or fructose percentage (r = –0.58). A total of 500 primers was used to screen between low and high DNA bulks for three individual sugar percentages. Ten RAPD markers, four amplified from `TAM Dulce' and six amplified from TGR1551, were significantly associated with QTL for at least one individual sugar percentage. Of the 10 markers identified, six were consistently associated with two to three traits. The OAU13.1350 obtained from `TAM Dulce' accounted for 13% and 19% of the phenotypic variation for sucrose and glucose percentages, while OAW06.600 obtained from TGR1551 explained 17% and 18% of the variation for the two traits. The OAA09.350 and OAU05.600 markers accounted for 4% to 13% of the variation for three sugar percentages. These markers associated with QTL for three individual sugar compositions could be useful in melon breeding for improving the mature fruit quality.

A new designer carrot, `BetaSweet', with high levels of anthocyanin, betacarotene, and crispy texture was developed by the Vegetable Improvement Center at Texas A&M Univ. The new carrot contained low levels of low-volatile terpenoids, responsible for the harsh flavor in carrots and high levels of reducing sugars. Carotenoid content increased with carrot maturity and stabilize at 120 days after sowing for orange and maroon genotypes; however, the maroon genotype was 35% higher than the orange cultivar. Anthocyanin, a cancer preventive compound and not detected in ordinary orange carrots, is present in `BetaSweet' maroon carrot with 89.8 mg·100 g^-1 of fresh weight. High percentage of soluble solids and succulence in the maroon cultivar seemed to contribute to the favored sweetness perception by consumers. A consumer taste panel showed a significant difference between orange and maroon genotype for sweetness, texture, and overall carrot flavor.