ABSTRACT
ABSTRACT This work describes the establishment of procedures to induce in vitro callogenesis from Poincianella pyramidalis (Tul.) L. P. Queiroz, Fabaceae, explants. Nodal, internodal and leaf segments were isolated from in vitro germinated seedlings and cultured in MS medium with 0, 2.5, 5 and 10 mg l-1 of 2,4-dichlorophenoxyacetic acid. After 30 days, the explants with induced callus showed a quadratic response for the segments nodal, internodal and leaf, with increasing the callus formation in 2,4-dichlorophenoxyacetic acid concentrations of 6.28, 6.49 and 4.91 mg l-1, respectively. In 30 days there was a linear oxidation rise with the increase to the 2,4-dichlorophenoxyacetic acid. After 60 days, oxidation values were minimum, at 2,4-dichlorophenoxyacetic acid concentrations of 5.13 mg l-1 (internodal) and 3.98 mg l-1 (leaf). The highest callus production was observed after 30 days in the presence of 6.09 mg l-1, 5.82 mg l-1 and 4.91 mg l-1 of 2,4-dichlorophenoxyacetic acid in nodal, internodal and leaf segments, respectively. After 60 days these segments showed peaks of production at 7.0 mg l-1 (nodal), 6.15 mg l-1 (internodal) and 5.08 mg l-1 (leaf) of 2,4-dichlorophenoxyacetic acid. For callus induction the intake of 2,4-dichlorophenoxyacetic acid was essential. The greater intensity in callus formation was observed in 4.91 mg l-1 in leaf segments after 30 days.
ABSTRACT
The different infestation levels of the pineapple bug, Thlastocoris laetus Mayr, were assessed in four regional pineapple cultivars: Cabeça-de-Onça (RBR-2), Senador Guiomard (SNG-3), Quinari (SNG-2) and Rio Branco (RBR-1), released by Embrapa Acre, in Rio Branco, State of Acre, Brazil. The numbers of nymphs and adults on shoots, leaves, crowns and fruits were counted weekly and the plant structures preferred by the pest were determined, as well as the population dynamics as a function of the phenologic stages of the cultivars. The pest population dynamics was determined by means of regression analysis, with curve fitting, and Pearson's linear correlation regarding these figures and those of the meteorological variables during that period. It was found a far as T. laetus infestation is concerned, that Cabeça-de-Onça (RBR-1) and Senador Guiomard (SNG-3) cultivars may be recommended, and the latter showed the highest pest infestation only during the fruit production stage, which is an economically favorable characteristic in terms of the number of control measures needed. It also showed the lowest number of plants infested, number of adults per plant and number of nymphs per plant, which were significantly different from the other cultivars. The correlation and regression studies regarding pest population and meteorological variables were not significant.
O nível de infestação do percevejo-do-abacaxi, Thlastocoris laetus Mayr, foi avaliado em quatro cultivares regionais de abacaxi: Cabeça-de-Onça (RBR-2), Senador Guiomard (SNG-3), Quinari (SNG-2) e Rio Branco (RBR-1), lançadas pela Embrapa Acre, na região de Rio Branco, AC. Foram realizadas contagens semanais do número de ninfas e adultos nos filhotes, folhas, coroas e frutos, a partir do que, determinou-se a dinâmica populacional da praga em função das fases do desenvolvimento fenológico das cultivares e as estruturas da planta preferidas para o ataque. Realizou-se ainda, análise de regressão e correlação linear de Pearson, entre esses valores e os das variáveis climáticas no período. Sob o aspecto de infestação de T. laetus, pode-se recomendar as cultivares Cabeça-de-Onça (RBR-1) e Senador Guiomard (SNG-3), sendo que a última apresentou as maiores infestações da praga somente no período de frutificação, o que representa uma característica economicamente vantajosa em relação ao número de aplicações de medidas de controle. Apresentou, ainda, os menores valores em relação ao número de plantas atacadas, número de adultos e ninfas/planta. Os estudos de correlação e regressão entre a população da praga e a variáveis meteorológicas não apresentaram resultados significativos.