Genetic improvement of early root vigor in melon (Cucumis melo L.) to enhance stand establishment.

摘要

Root vigor is an important component of transplant health and successful stand establishment in melons and other vegetable crops. Environmental factors, which impact root traits related to vigor, have been examined in some vegetable crops, but few studies on genetic variation for these traits have been published. Greenhouse experiments were conducted to evaluate early melon root vigor in a diverse selection of melon germplasm lines and cultivars. Seven accessions, representing three horticultural groups of melons (cantalupensis, inodorous, momordica), were grown in pasteurized sand, and evaluated for key root morphology traits at four stages of development. Significant differences among cultivars were observed for total root length, fine root length and root area 7, 14 and 21 days after germination. However, by 28 days, all accessions were statistically equivalent for these root traits. The entries, 'Deltex' and 'PI x TDI,' exhibited superior root vigor during the first two weeks of development, compared to the commercial cantaloupe cultivars, 'Caravelle' and 'Magnum 45.' These two lines also exhibited superior field performance for both root and vine vigor at Weslaco, and consequently were more tolerant to infection by Monosporascus cannonballus. Subsequent breeding for enhanced root vigor at Weslaco has resulted in many advanced inbreds with improved stress tolerance, vine vigor and fruit quality.