Search Results
Abstract
Iron chlorosis often develops in blueberries (Vaccinium) grown on soils with a pH above 5.2. Seedlings of 4 blueberry intra- and interspecific progenies, involving V. ashei, V. corymbosum, and V. darrowii, were tested for Fe-efficiency (use of Fe) by growing them in nutrient solutions containing different concentrations of CaCO3 to vary the pH. Plants received Fe during the first 4 harvests (up to 75 days) but received no Fe during the subsequent 2 harvests. The Fe supply for plant growth in the last 2 harvests was limited to that available in the roots. T-65 × US 67 blueberry plants [a 3-species hybrid of V. ashei × (V.darrowii × V. corymbosum)] lowered the pH of the nutrient solution by releasing H+ from their roots which freed Fe from root accumulations and made it available for plant use. ‘Climax’ × T-151 (V. ashei × V. ashei) progeny did not do this. Seedlings of V. corymbosum and those from a cross of V. corymbosum with V. darrowii were intermediate in their response.
Abstract
Paper chromatograms of flavonoid compounds extracted from the leaves of 43 snap bean cultivars and breeding lines produced characteristic patterns which allowed all but 7 to be classified into one of 3 major categories. One of the flavonoid compounds was consistently associated with bush and not runner type plants and was thus useful for early classification of populations segregating for plant type. The high degree of similarity among cultivars for a set of characters which one might expect to be distributed at random suggests a rather narrow gene base for this crop.
Abstract
Roots of several cultivars of strawberry (Fragaria × ananassa Duchesne) were examined for mycorrhizae at the various stages required to produce nursery stock. First-year screenhouse plants were always non-mycorrhizal, but colonization of plants growing in fumigated foundation (2nd year) and certified (3rd year) fields was highly variable. As a result, certified stock being sold from Nova Scotia is often non-mycorrhizal. When present, mycorrhizae appeared to correlate with the presence of viable propagules in the soils after fumigation. In a greenhouse inoculation trial, all cultivars tested, including those with resistance to red stele disease (Phytophthora fragariae Hickman), became equally infected. Since mycorrhizae were also responsible for significant increases in growth and fruit production, inoculation of strawberry plants at the screenhouse stage is being considered.
Early okra production was evaluated using `Clemson Spineless' transplants grown under clear polyethylene mulch plus VisPore row cover (VCM), black polyethylene mulch plus VisPore row cover (VBM), clear polyethylene mulch (CM), black polyethylene mulch (BM) and bare soil (BS) for two years. Early yield (1st four harvests in early June) was significantly greater for VCM treatment while total marketable yield at the end of 8 wks were significantly greater for VCM, BM, and VBM treatments, respectively in both years. Enterprise budget analysis showed that VCM and BM treatments had the highest net-return to management on a per acre basis.
Early okra production was evaluated using `Clemson Spineless' transplants grown under clear polyethylene mulch plus VisPore row cover (VCM), black polyethylene mulch plus VisPore row cover (VBM), clear polyethylene mulch (CM), black polyethylene mulch (BM) and bare soil (BS) for two years. Early yield (1st four harvests in early June) was significantly greater for VCM treatment while total marketable yield at the end of 8 wks were significantly greater for VCM, BM, and VBM treatments, respectively in both years. Enterprise budget analysis showed that VCM and BM treatments had the highest net-return to management on a per acre basis.
Commercial production of cacao in Hawaii is increasing, and this trend is expected to continue over the next several years. The increased acreages are being planted with seedlings from introduced and uncharacterized cacao populations from at least three initial introductions of cacao into the islands. Productive seedlings have been selected from a planting at Waialua, Oahu. The parents of these selections were believed to be the population at the Hawaii Agriculture Research Center (HARC) at Kunia; however, potential parental populations also exist at Univ. of Hawaii research stations at Waimanalo and Malama Ki. Using microsatellite markers, we analyzed the potential parental populations to identify the parents and determine the genetic background for 99 productive and 50 unproductive seedlings from the Waialua site. Based on 19 polymorphic microsatellite loci the parental population was identified as trees from Waimanalo and not trees from Malama Ki or Kunia. The Kunia and Malama Ki populations were very similar with low allelic diversity (A = 1.92) and low unbiased gene diversity (Hnb) of 0.311 and 0.329, respectively, and were determined to be Trinitario in type. The Waimanalo, productive seedling, and unproductive seedling populations had much higher levels of genetic diversity with Hnb of 0.699, 0.686, and 0.686, respectively, and were determined to be upper Amazon Forastero hybridized with Trinitario in type. An additional 46 microsatellite markers were amplified and analyzed in the Waimanalo parents, productive, and unproductive seedlings for a total of 65 loci. Seventeen loci contained alleles that were significantly associated with productive seedlings as determined by Armitage's trend test. Of these, 13 loci (76.4%) co-located with previously reported quantitative trait loci for productivity traits. These markers may prove useful for marker assisted selection and demonstrate the potential of association genetic studies in perennial tree crops such as cacao.
Three horticultural races of avocado (Persea americana Mill.) are known: Guatemalan, Mexican, and West Indian. Each race has unique characteristics and current commercial varieties have been selected from within the races or from interracial hybrids. Using 14 microsatellite loci we investigated the genetic variation among 224 accessions (394 plants) maintained at the National Germplasm Repository (NGR) in Miami, Fla., and a set of 34 clones from the University of California South Coast Field Station (SCFS) located in Irvine, Calif. The 14 microsatellite loci had an average of 18.8 alleles per locus and average unbiased genetic diversity was 0.83. The total propagation error in the collection, i.e., plants that had been incorrectly labeled or grafted, was estimated to be 7.0%. Although many unique alleles did exist, no useful race-specific markers were found. A general concordance between the horticultural race and the clusters obtained from molecular data was observed. Principal Coordinate Analysis (PCA) grouped the Guatemalan and Mexican races into two distinct clusters. The West Indian also grouped into a unique major cluster but with an outlying group. Using the PCA a change in the racial designation or interracial hybrid status for 50 accessions (19.7%) is proposed. The unbiased gene diversity estimate was highest in the Mexican and Guatemalan races and lower in the West Indian group. This demonstrates the need to collect more of the West Indian germplasm to broaden the genetic diversity and to emphasize the identification of individuals conferring resistance to Phytophthora Root Rot (PRR).
Effects of planting methods and rowcover on the production of yellow crookneck squash, Cucurbita pepo L. var. melopepo Alef., were evaluated over 2 years at the E.V. Smith Research Center, Shorter, Ala. Summer squash was direct-seeded or transplanted in the field with or without black plastic mulch and grown with or without rowcover. Yield of transplanted squash was significantly increased over the same squash direct-seeded. Neither plastic mulch nor rowcover had an effect on summer squash production. Transplants matured 8 to 10 days earlier than the direct-seeded plants.
Abstract
In the Cultivar and Germplasm Release article “‘Allgold’ and ‘Goldilocks’ Peaches” by J.N. Moore, Roy C. Rom, Stanley A. Brown, and William A. Sistrunk [HortScience 19(6):891–892, 1984], the captions of Figures 2 and 3 were reversed. The selection test numbers given in the text for these cultivars (‘Allgold’ = A-142; ‘Goldilocks’ = A-15) are correct.
Yellow crookneck `Dixie' hybrid summer squash, Cucurbita pepo L. var. melopeop Alef., was evaluated at E.V. Smith Research Center, Shorter, Alabama. Summer squash was grown in single rows spaced 6 feet apart. Plants were seeded 18 inches apart within 20-foot row plots. Treatments were: 1) black plastic mulch (BPM), 2) yellow painted plastic mulch (YPM), 3) white plastic mulch (WPM), 4) bare soil (BS), 5) aluminum painted plastic mulch (APM) and 6) bare soil with Diazinon insecticide (BSI). Aphid traps caught more aphids in BS or BPM plots than those from APM or YPM plots. The onset of mosaic disease incidence of squash infected with the two viruses identified as zucchini yellow mosaic and cucumber mosaic was delayed by as much as three weeks when compared to BSI or BS. Summer squash planted in APM, WPM, YPM and BPM produced 96%, 98%, 75% and 21%, respectively, more total squash yield than that produced on bare soil (control). A higher percentage of green squash (virus infected) was produced from plants grown over BPM (72%), BSI (68%), BS (59%), YPM (57%) or WPM (57%) than from APM (39%)