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  • Author or Editor: J. Brent Loy x
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‘Autumn Pride’ is an open-pollinated strain of winter squash (Cucurbita maxima Duch.) that was released by the New Hampshire Agricultural Experiment Station in 1981. Its unique feature is a bush plant that produces large hubbard-type fruit.

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Premature harvest of acorn squash is a widespread problem because fruits reach maximum size and optimum color within 20 days after pollination (DAP), well before peak dry matter and sugar content occur. The present study was conducted to determine the relationship between harvest date and physiological factors affecting eating quality in Cucurbita pepo L. squash. In the summer of 2005, C. pepo squash cultivars were evaluated at three harvest dates, 25, 35, and 45 days after pollination (DAP), with or without a 10-day storage period at 21 °C. Four F1 hybrid cultivars carrying powdery mildew tolerance (PMT) were evaluated: a semi-bush, commercial acorn cultivar (`Tip Top'), a high quality experimental acorn, bush hybrid (NH1634), and two sweet dumpling-type, semi-bush hybrids (NH1635 and 1636). Data were collected on mesocarp DW, oBrix (soluble solids), and partitioning of biomass between mesocarp tissue and developing embryos during storage. Peak DWs of 20% to 21% occurred at 25 DAP in NH1634, 1635 and 1636, and at 35 DAP in Tip Top (19.5 %). At 25 DAP, Brix was low (means of 5.9 to 7.2) across all cultivars. With harvest at 25 DAP plus 10 days storage, oBrix was low in Tip Top (7.1), but was higher than 10 in NH1634 and NH1636. Brix reached near maximum (13 to 15) at 45 DAP in NH1634, 1635 and 1636, and at 55 DAP in Tip Top (12). Embryos were small (DW = 8 to 19 mg) at 25 DAP and grew fairly linearly to a maximum at 55 DAP. Mean embryo DW at 55 DAP was 87.5 mg for Tip Top, 76.9 mg for NH1636, 57.1 mg for NH1634, and 28.5 mg for NH1635. The proportion of total fruit biomass expressed as energy equivalents (kJoules) allocated to embryos in mature fruit (45 DAP + 10 days storage) was 11.8% in NH1635, 18.7% in NH1634, 27.4% in Tip Top, and 30.2% in NH1636. Reallocation of assimilates from mesocarp tissue to developing embryos was a major contributing factor, along with respiration, to a reduction in mesocarp dry matter during storage.

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Acorn squash (Cucurbita pepo L.) is one of the three major classes of squash consumed in North America. Breeding improvements over the past 30 years have focused on more compact cultivars, earlier maturity, darker rind color, and powdery mildew tolerance (PMT). Our observations from sampling acorn squash from local supermarkets at different times during the year show that eating quality is highly variable, and most often, not acceptable. Our taste tests indicate that for acceptable eating, quality acorn squash should have °Brix of 10 or higher, flesh %DW above 16, and a smooth, nonfibrous texture. Most commercial cultivars fail to meet the above minimum criteria for quality. Proper harvest time is a major determinant of squash eating quality. To obtain adequate °Brix levels, squash should not be harvested until at least 50 days after pollination (DAP). If squash are harvested between 25 to 40 DAP and then stored for two or more weeks, °Brix levels may increase to acceptable levels, but some mesocarp reserves will be remobilized to developing seeds, reducing mesocarp %DW and lowering eating quality. A major goal of the squash breeding efforts at the University of New Hampshire has been to increase mesocarp %DW for obtaining more consistent eating quality. We have evaluated several experimental PMT hybrids during the past 5 years, and in some of these, flesh DW has averaged 17% or higher, and eating quality has been rated consistently very good. The adoption of better quality acorn cultivars together with implementing proper harvest times and storage conditions could appreciably increase per capita consumption.

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The expression and inheritance of the fused vein trait in Cucurbita pepo were investigated. The fused vein inbred, NH2405, was crossed to normal lines, NH614, and NHBP10. Reciprocal F1, F2, F3 and BC populations were generated and examined for leaf type segregation in field and greenhouse environments. Although the fused vein phenotype is stable in NH2405, it exhibited a continuum of expression in segregating populations. The onset of vein fusion ranged from the fourth to the tenth leaf stage and degree of fusion varied from slight (1-5 cm) to extreme (10-20 cm). Inheritance ratios varied with population, conditions of production, and direction of cross. Most segregating populations fit either a single or double recessive gene model, however, a quarter of the populations showed no or low fused vein recovery. A feasible explanation for the distorted inheritance is that the fused vein trait is a gametophytic subvital, governed by a single recessive gene, fv. Although less likely, a double recessive, subvital model cannot be ruled out.

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Two experiments were conducted to test and delineate gametophytic subvitality of the fused vein trait in Cucurbita pepo. Gametophytic subvitality was verified by comparing pollen tube growth for fused vein and normal pollen in situ. Microscopic examination of partitioned, co-pollinated distillate flowers revealed inferior fused vein gametophyte performance. Normal pollen tubes grew faster and were significantly more abundant in the lower portion of the style. The consequences of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of pollen competition. Fused vein, normal and F1 lines were pollinated with fused vein, normal, F and a 50:50 pollen mix at three different pollen loads. Fused vein pollen generated significantly fewer seed per fruit in all female genotypes. As a constituent in F, or mixed pollen, it produced significant seed yield reductions at the low pollen load. In F1 and testcross populations, a reduction in pollen load and therefore pollen competition significantly increased the number of fused vein individuals in segregating populations.

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The morphology, growth rate and anatomy of the fused vein trait were characterized in Cucurbita pepo using the inbreds NH2405 (fused vein), NH7210 (moderately fused vein), and NH614 (normal). Morphological analysis showed that the trait is characterized by a partial fusion of the five primary leaf veins. Fusion begins at the distal point of the petiole and extends along the central vein. Branching of the veins is delayed and there is a reduction of the interveinal leaf blade. Consequently, the upper leaf surface appears puckered or wrinkled. Depending on genetic background, the onset of fused vein leaf production starts at the fourth to tenth leaf stage and continues throughout vegetative growth. The extent of fusion increases with leaf number but stabilizes by the twentieth leaf stage maximum extent of vein fusion also varies with genetic background (5-20 cm). Though fused vein and normal inbreds differed in the rate and pattern of leaf growth, examination of F2 and BC populations revealed no significant effect of the fused vein trait on leaf number, leaf size, and rate of leaf initiation. Anatomical examination revealed different vascular patterns in the transition zone between petiole and leaf blade for normal and fused vein leaves. In normal leaves, the vascular bundles of the petiole enlarge and coalesce to form a vascular crescent. The crescent reorganizes and diverges as large vascular columns and pairs of smaller flanking vascular bundles into each vein. In contrast, two cycles of enlargement, coalescence, and dispersal occur in fused vein leaves.

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Five tomatillo (Physalis ixocarpa Brot. ex Hornem) cultivars available from commercial seed companies (`De Milpa', `Puebla Verde', `Purple Tomatillo', `Tomatillo' and `Toma Verde') and four Physalis L. accessions (PI 197691, PI 270459, PI 291560, and PI 309812) were grown in 1997 and 1998 at Kingman Research Farm, Durham, N.H. Three manual harvests per plot were performed each year, recording data of total fruit weight, number of fruit and average fruit weight for each genotype. There were statistically significant differences between tomatillo genotypes for all three traits. Statistically significant differences between the 2 years were found for fruit number and average fruit weight per genotype. Over both years, total fruit weight varied from 29.7 to 63.7 t·ha-1 (13.3 to 28.4 ton/acre). Fruit numbers per plant varied from 83 to 330, and average fruit weight varied from 18.0 to 38.3 g (0.6 to 1.3 oz). PI 197691 and PI 270459 performed better than some of the commercial cultivars indicating their potential to be used as germplasm for breeding. A basket-weave trellising system which kept plants upright was tested. This made harvest easier and potentially can be used for tomatillo culture.

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This study was undertaken to determine the inheritance of a glabrous trait discovered in yellow straightneck summer squash (Cucurbita pepo L.) in 1992 and to compare trichome distribution and anatomy and morphologic features that relate to productivity in glabrous and nonglabrous genotypes. Inheritance data from 1994, 2003, and 2004 confirm that the glabrous trait is inherited as a single gene recessive, designated gl-2, but that in some segregating F2 populations with a zucchini or caserta (C. pepo ssp. pepo) background, there is a deficiency of glabrous segregants. Nonglabrous (NG) plants bore numerous trichomes on stems, petioles, leaf blades, and fruit. Trichomes were simple (unbranched), and most were either conical and unicellular or small filiform and multicellular (two to five cells). However, some larger multicellular trichomes with compound feet were found on major leaf blade veins and along vein tracts of petioles. Large, multicellular trichomes with compound feet were only occasionally present on leaf blades and petioles of glabrous (G) plants, and other trichome types were much reduced. This reduction gives fruit and foliage a smooth, waxy feel and largely eliminates trichome damage to fruit and skin irritation to workers during harvesting. Leaf number, staminate to pistillate flower ratios, and fruit size were not significantly different between glabrous (gl-2/gl-2) and nonglabrous (Gl-2/gl-2) backcross (BC) genotypes. In one of two BC populations, pistillate flowering was 2 d earlier in NG as compared with G plants. The glabrous gene reduced the size of leaf blades in two BC populations; however, differences in total leaf areas were not statistically significant at P = 0.05. A comparison of leaf numbers and size among G and NG parental plants and reciprocal F1 hybrids derived from three separate crosses did not reveal a consistent effect of the gl-2 gene on plant morphology. Earliness and productivity of the best glabrous hybrids were similar to that of popular commercial cultivars.

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Abstract

Yields of muskmelon (Cucumis melo L.) were not significantly different between those grown under slitted polyethylene or those grown under polyester row covers, either with or without supporting wire hoops. Row covers combined with black polyethylene mulch increased both earliness and total yields of muskmelon as compared to those grown on black polyethylene mulch alone. Polyester appeared to be a potentially useful material for row cover culture of suitable crops because of its heat retention, light weight, relatively high tensile strength, and ease of installation.

Open Access
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Abstract

“The French market gardens in the environs of Paris and other large cities are very curious-looking places.” Thus was the report in McCall's magazine in July of 1909 (1) in reference to the burgeon of bell glasses (cloches) used for winter and spring production of vegetables. Perhaps the gardening scenery around Paris was the fulfillment of the words of a classic English gardener, Mrs. Loudon, who in 1869 stated, “The cloche is quite unknown to the majority of amateurs, but nothing ever introduced to their notice will prove of greater or more varied utility” (4). By 1910, McKay (5) had placed the number of bell glasses in Paris at 2,160,000. Hence, the bell glass/cloche is the forerunner of the row cover/tunnel which is so prevalent in Europe and Japan today and which is becoming more popular in the United States.

Open Access