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  • Author or Editor: Martha Elena Pedraza-Santos x
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Effects of inoculation with arbuscular endomycorrhizal fungi (Acaulospora scrobiculata and Glomus mosseae) on acclimatization and growth of chrysanthemum (Dendrathema glandiflora Tzevelev) plants, propagated in vitro, under different conditions of fertilization (0, 20, and 40 mg·L-1 of NPK) were studied. Mycorrhizal colonization did not influence surviving percentage of chrysanthemum plantlets during the acclimatization stage; however, we could colonize the developing roots and reduce the amount of inoculum needed and beneficial effects on plant growth were obtained during early stages of colonizing. Plant growth in greenhouse was regulated by synergism between the effect of endomycorrhizal fungus type and soil fertilization with N, P, and K. Effects of A. scrobiculata were observed as an increasein number of leaves, leaf area, stem diameter, root volume and fresh and dry weight of leaves, stem and root. The G. mosseae fungus improved N, P, Mg, and Zn content in leaves; P, K, Ca, Mg, and Zinc in stem and Ca content in root. On the other hand, A. scrobiculata only increased N content in leaves, stem and roots; P content in leaves and roots, and Ca content in stem. Percentage of mycorrhizal colonization on roots was affected by adding N, P, and K to soil. The highest values were obtained with fertilization doses of 20 mg·L-1. The number of spores of mycorrhizal fungi was increased by adding fertilizer to soil (40 mg·L-1 of NPK).

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Phytophthora blight of vegetables caused by Phytophthora capsici causes significant economic losses in production of Solanaceae and Cucurbitaceae crops in Mexico. The development of universal resistant chili pepper cultivars is challenging due to the diverse virulence phenotypes produced by P. capsici. The objective of the study was to characterize the diversity of phenotypic interactions for P. capsici isolates recovered from production fields in Michoacán, Mexico, to facilitate the development of resistant cultivars. Virulence phenotypes were characterized for 12 isolates of P. capsici using 26 Capsicum annuum New Mexico Recombinant Inbred Lines (NMRILs) in greenhouse conditions. Criollo de Morelos CM-334 and California Wonder were used as resistant and susceptible controls, respectively. Seedlings at the four to eight true leaf stage were inoculated with 10,000 zoospores per seedling and disease severity was evaluated at 20 days post-inoculation. Two of the P. capsici isolates did not infect any pepper host even though the isolate was less than a year old. The 10 virulent isolates were designated in 10 virulence phenotypes. The information generated by this study is of utmost importance for efforts of producing resistant cultivars specific for Michoacán producers.

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