Caracterização fisiológica da tolerância à seca em Coffea canephora: contribuição relativa do sistema radicular e da parte aérea

• Autor(a) principal: Silva, Vânia Aparecida
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1008
• topic: Café; Tolerância à seca; Porta-enxerto; Ácido abcísico; Coffea canephora; Coffee; Drought tolerance; Grafted plants; Abscisic acid; Coffea canephora; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::FISIOLOGIA DE PLANTAS CULTIVADAS

With the intent to evaluate the relative contribution of the root system in Coffea canephora to drought stress tolerance, was performed reciprocal grafting experiments between genotypes with contrasting tolerance traits (clone 109, sensible, and clone 120, tolerant). The plants used in these experiments were control plants 109 and 120, and grafted plants 120/109, 120/120, 109/110 and 109/109. All plants were cultivated in 12 L pots for 6 months, under greenhouse conditions. After growth for six months, half plants remained irrigated, whereas the other half was subjected to water stress by withholding irrigation. Plants 120 and grafts having 120 as rootstock have showed slower reduction of predawn leaf water potential (ψpd), deeper roots and lower carbon isotopic discrimination under water deficit. These plants also have shown bigger reduction in gs after light decrease in ψpd = -0,5 MPa and higher leaf ABA concentration under moderate water deficit (ψpd = -1,0 e -1,5 MPa). However changes in ABA concentration was not associated with changes in gs, and no differences for gs under moderate and severe water deficit were observed between different plants. Additionally, root ABA concentration was bigger in plants having the 120 root system, both in presence or absence of drought. These plants also have shown, under severe water deficit, less pronounced reductions in A, lower level of ion leakage, lower APX and CAT activities, and lower levels of hexoses, amino acids and proline. Otherwise, the 120 scion was also able to contribute to drought tolerance, since it was able to retard the evolution of water deficit, to result in higher leaf ABA concentration under moderate stress and in lower leaf ion leakage. Altogether, these data show the important contribution of root system to drought tolerance in C. canephora, and suggest the probable viability of the use of grafting of tolerant rootstocks for improvement of drought tolerance of more drought sensible genotypes that have other important agronomical traits.