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- Author or Editor: James R. McFerson x
Fifty-two germplasm accessions of Chinese vegetable brassicas were analyzed using 112 random amplified polymorphic DNA (RAPD) markers. The array of material examined spanned a wide range of morphological, geographic, and genetic diversity, and included 30 accessions of Brassica rapa L. (Chinese cabbage, pakchoi, turnip, and broccoletto), 18 accessions of B. juncea (L.) Czern. (leaf, stem, and root mustards), and four accessions of B. oleracea L. ssp. alboglabra (Chinese kale). The RAPD markers unambiguously identified all 52 accessions. Nei-Li similarities were computed and used in unweighed pair group method using arithmetic means (UPGMA) cluster analyses. Accessions and subspecies were clustered into groups corresponding to the three species, but some accessions of some subspecies were most closely related to accessions belonging to other subspecies. Values for Nei-Li similarities suggest that Chinese cabbage is more likely to have been produced by hybridization of turnip and pakchoi than as a selection from either turnip or pakchoi alone. RAPD markers are a fast, efficient method for diversity assessment in Chinese vegetable brassicas that complements techniques currently in use in genetic resources collections.
Screening of 107 bean cultivars and plant introductions (PI) by 2-dimensional electrophoresis revealed only 3 different phaseolin patterns: Tendergreen (T), Sanilac (S), and Contender (C). The majority of the lines had either the ‘T’ (25%) or ‘S’ (69%) phaseolin patterns, with only 6% having the ‘C’ pattern. Phaseolin pattern was not strictly associated with commercial class but most cultivars with the ‘T’ pattern were snap beans, while the majority of lines with the ‘S’ pattern were dry beans. Furthermore, the phaseolin types of 15 cultivars were associated with previous cultivar groupings that were based on calculations of genetic relationships. A genetic distinction was noted between the groups of cultivars containing the ‘T’ and ‘S’ phaseolin patterns.
Advances in precision agriculture technologies provide opportunities to improve the efficiency of agricultural production systems, especially for high-value specialty crops such as fresh apples (Malus domestica). We distributed an online survey to apple growers in Washington, New York, and Michigan to elicit stakeholder perceptions of precision agriculture technologies. Findings from this study demonstrated that growers are willing to adopt precision agriculture technologies when they receive results from applied research projects and are engaged with active extension programs. The availability of customized services and purchasing and rental options may minimize the effects of the economies of size that create barriers to adopting increasing access to technologies. Finally, respondents deemed collaborative efforts between industry and academic institutions crucial for adapting the innovation to better address the needs of growers.
Malus sieversii, the main progenitor of domesticated apple, is native to areas in Central Asia. To better represent Malus wild germplasm in the USDA–ARS germplasm collections, maintained in Geneva, N.Y., a cooperative project was initiated with the Republic if Kazakhstan to collect and assess that country's wild populations of M. sieversii and to develop more secure in situ reserves to complement ex situ holdings in the United States and Kazakhstan. To date, four exploration trips to the region have included participants from the United States, Kazakhstan, Canada, New Zealand, and South Africa. Four Kazkh scientists have toured USDA–ARS sites, exchanged information, and collected germplasm in the United States greenhouse screens of 1600 have revealed potentially new sources of resistance to apple scab, cedar apple rust, and fire blight. An isozyme analysis of maternal half-sib families from four regions suggests the populations of M. sieversii collected represent a single panmictic population, with over 85% of total genetic variation due to differences among families. The most recent collections in 1995 were directed towards more ecologically diverse regions, including a site (Tarbagatai) at the most northern limit for M. sieversii equivalent to northern Minnesota in the United States. Some trees in this region produced fruit nearly 70 mm in diameter with excellent aroma, firmness, and color. This germplasm is being systematically characterized for horticultural traits, pest and disease resistance, and molecular markers.
Clonally propagated crops, unlike seed-propagated crops, require intense and costly maintenance, generally in ex situ field gene banks. Consequently, large germplasm collections of tree species especially, are difficult to conserve in a well-replicated fashion and are vulnerable to damage from environmental stresses. Accordingly, long-term storage in liquid nitrogen presents a viable conservation alternative. To assess effectiveness of one approach to cryopreservation, dormant buds from 64 apple (Malus ×domestica Borkh. and other Malus spp.) accessions were collected and preserved in liquid nitrogen using a dormant-vegetative-bud method. Buds were retrieved from liquid nitrogen storage, rehydrated, and grafted onto rootstocks to determine survival. Mean recovery was 76% for 40 cold-hardy accessions, 66% for 20 moderately cold-hardy accessions, and 24% for four cold-tender accessions (range: 16% to 100%). Only four accessions had ≤25% recovery while 54 accessions had ≤50% recovery and 35 accessions had ≤75% recovery. No significant decline in recovery of these accessions by bud grafting occurred after 4 years of liquid nitrogen storage.
We conducted audience surveys at three major peach producer meetings across the United States. We found that the relative importance assigned to fruit quality and tree traits by producers varied across producers’ end markets. Fresh peach producers indicated fruit flavor and size were the most important fruit quality traits, whereas processed peach producers viewed fruit size, fruit firmness, and absence of split pits as being the most important traits for a successful peach cultivar. These results have potential to ensure that peach breeding programs are consonant with fresh and processed peach producers’ needs for fruit and tree traits.
Developing new cherry cultivars requires breeders to be aware of existing and emerging needs throughout the supply chain, from producer to consumer. Because breeding programs in perennial crop plants like sweet and tart cherries require both extended time and extensive resources, understanding and targeting priority traits is critical to improve the efficiency of breeding programs. This study investigated the relative importance of fruit and tree traits to sweet and tart cherry producers using ordered probit models. Tart cherry producers considered productivity and fruit firmness to be the most important traits, whereas sweet cherry producers regarded fruit size, fruit flavor, fruit firmness, freedom from pitting, and powdery mildew resistance as important traits. The location of producers’ orchards and their demographic backgrounds influenced their perceptions of the importance of traits. Our findings provide a quantitative basis to reinforce existing priorities of breeding programs or suggest new targets.
Systematic studies of the relative importance of apple traits for U.S. apple producers to inform U.S. apple breeding programs have been lacking. To fill this gap, a series of audience surveys with instant feedback at five apple producer meetings across the United States was conducted. The traits included in this study were fruit crispness, juiciness, firmness, flavor, soluble solids concentration, sugar–acid balance, shelf life at retail, freedom from storage disorders, host plant disease resistance, and other fruit and tree traits provided by the producer. Producers rated fruit flavor and crispness as the most important traits for a successful apple cultivar. The relative importance assigned to traits was associated with growing location and producers’ years of experience in the decision-making process of managing apple orchards. This study contributes directly to a larger effort that provides breeding programs with systematic knowledge of trait preferences of supply chain members, including producers, and should result in a more targeted approach to developing and commercializing new apple cultivars.
U.S. peach (Prunus persica) growers are challenged by the need to protect their orchards from economically damaging diseases and deliver fruit with the quality expectations of the supply chain. This study focuses on the U.S. southeastern peach sector, including North Carolina, South Carolina, Alabama, Virginia, and Georgia. This region offers a useful case to analyze growers’ preferences for both fruit quality and disease resistance. We collected primary data from peach operations in 2016 and 2018. In both surveys, a discrete choice experiment was used to advance the understanding of how peach growers in the southeastern United States value fruit quality (i.e., fruit size and external color) vs. disease resistance [i.e., brown rot (Monilinia fructicola)]. The sample of growers surveyed in 2016 growers placed a greater importance on the fruit quality attribute that would imply higher returns, that is, fruit size (expressed as fruit diameter) compared with improvements in brown rot resistance and external fruit color. Meanwhile, the sample of growers surveyed in 2018 placed a higher importance to brown rot resistance and external fruit color compared with fruit size. Findings consistent for the 2 years are that growers are willing to pay for larger rather than smaller improvements in brown rot resistance, and that a large improvement in brown rot resistance is more important than external fruit color.