Published online by Cambridge University Press: 19 September 2011
One hundred and five okra cultivars were evaluated in the field for resistance to the leafhopper Amrasca biguttula biguttula (Ishida) during the 1989–1990 season. On the basis of nymphal abundance and leafhopper injury index two resistant (Siswal Local and IC 7194) and nine moderately resistant [IC 6653, IC 8899, IC 13617, Sel. 1, HB 94, IC 6316,6 Dhari, Sel. 2–2 and Line 6(1)] genotypes were identified. Both of the resistant, two moderately resistant (Line 6(1) and IC 13617) and two highly susceptible (Pusa Sawani and Pusa Reshmi) genotypes were retested in 1990–1991. Resistant genotypes had significanlty (P < 0.05) fewer nymphs (18.5 to 22.0 nymphs/leaf) and lower values of injury index (2.2) compared with the other varieties. Nymphal duration was also longer (9.3 to 9.8 days) and nymphal survival lower (41.7 to 47.5%) in resistant cultivars. Higher trichome density, longer trichome length and higher concentration of sugars, silica, potassium, tannins and phenols in the leaves of resistant cultivars were associated with resistance to leafhopper.
Cent cinq cultivars de gombo ont été évalués en champs pour la résistance à la cicadelle Amrasca bigutulla bigutulla (Ishida), au cours de la saison 1989–1990. Sur base de l'abondance des nymphes et de l'index des dégâts infligés par les cicadelies, deux génotypes résistants (Siswal Local et LC 7194) et neuf génotypes moyennement résistants [(IC 6653, IC 8899, IC 13617), Sel. 1, HB 94, IC 6316, 6 Dhari, Sel. 2–2 et Line 6(1)] ont été identifiés. Les deux génotypes résistants et deux moyennement résistants (Line 6(1) et IC 13617) ainsi que deux autres hautement sensibles (Pusa Sawani et Pusa Reshmi) ont été de nouveau testés en 1990–1991. Comparés aux autres variétés, les genotypes résistants avaient significativement (P < 0.05) moins de nymphes (18, 5–22 par feuille) et leur index de dégâts était bas. Au sein des cultivars résistants, la durée de développement nymphal était aussi longue (9, 3–9, 8 jours) et la survie basse (41, 7–47, 5%). Une haute densité de trichome, un trichome trés long ainsi qu'une haute teneur en sucres, en silice, en potasse, en tannins et en phénols dans les feuilles des cultivars résistants ont étaient associés à la résistance contre les cicadelles.
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