ABSTRACT
O objetivo deste trabalho foi avaliar as respostas da cana-de-açúcar submetida à deficiência hídrica por meio de pigmentos fotossintéticos (clorofilas a, b, total a + b, relação clorofilas a/b e carotenoides) e verificar o uso do índice SPAD como ferramenta de diferenciação de cultivares. O experimento foi conduzido em casa de vegetação, onde quatro cultivares (IACSP95-5000, RB835054, RB928064 e SP80-3280) foram cultivadas em vasos. Após 65 dias do plantio, foram implementados dois tratamentos, sem deficiência (-D) e com deficiência hídrica (+D). Cultivares de canade- açúcar respondem diferentemente em relação aos pigmentos fotossintéticos quando submetidas à deficiência hídrica. As cultivares IACSP95-5000 e RB928064 têm menor efeito do estresse por falta de água, atribuído à capacidade da manutenção dos conteúdos de clorofilas e de carotenoides, além de maiores valores de índice SPAD, sob essa condição. A deficiência hídrica afeta com maior intensidade as cultivares RB835054 e SP80-3280 devido às maiores reduções nos pigmentos fotossintéticos e no índice SPAD. Índice SPAD é correlacionado com conteúdo de clorofilas e carotenoides em cana-de-açúcar e pode ser utilizado como técnica na seleção de cultivares tolerantes à deficiência hídrica em programas de melhoramento genético.
The objective of this study was to evaluate the responses of sugar cane subject to water stress by photosynthetic pigments (chlorophylls a, b, total a + b, ratio chlorophylls a/b and carotenoids) and verify the use of SPAD index as a cultivar differentiation tool. The experiment was carried out in a greenhouse, where four cultivars (IACSP95- 5000, RB835054, RB928064 and SP80-3280) were grown in pots. After 65 days of planting, two treatments were implemented, i.e., with no stress (-D) and with water stress (D +). Cultivars of sugar cane respond differently in relation to photosynthetic pigments when subjected to water deficit. Cultivars IACSP95-5000 and RB928064 have less effect of drought, that is attributed to the ability of maintaining the chlorophyll and carotenoid content, as well as higher SPAD index values under this condition. Water stress affects with more intensity the cultivars RB835054 and SP80-3280 due to higher reductions in photosynthetic pigments and SPAD index. SPAD index is correlated with chlorophyll and carotenoid content in sugar cane and can be used as a technique for selecting tolerant cultivars to drought in breeding programs.
Subject(s)
Photosynthesis , Carotenoids , Chlorophyll , Saccharum , PhotochemistryABSTRACT
The objective of this study was to compare the gas exchange, photosynthetic capacity and water potential of sugarcane genotypes cultivated under water deficit conditions imposed during the initial growth phase. Experiments were performed in a greenhouse using two sugarcane genotypes namely: HoCP93-776 (drought susceptible) and TCP02-4587 (drought tolerant). Sixty days after planting, two different water treatments were applied (i.e., with or without water deficit). At 0,30 and 60 days after the treatment, gas exchange variables were evaluated for their relationship with water use, intrinsic instantaneous water use efficiency and instantaneous carboxylation efficiency. The SPAD index, photosynthetic pigments, water potential and relative water content in the leaves were also analyzed. The genotype HoCP93-776 was more sensitive to drought treatment as indicated by the significantly lower values of SPAD index, photosynthetic pigments, water potential (Ψw) and relative water content (RWC) variables. The genotype TCP02-4587 had higher water potential, stomatal control efficiency, water use efficiency (WUE), intrinsic instantaneous water use efficiency (WUEintr), instantaneous carboxylation efficiency and photosynthetic capacity. The highest air vapor pressure deficit during the drought conditions could be due to the stomatal closing in the HoCP93-776, which contributed to its lower photosynthetic capacity.
ABSTRACT
Notifica-se a ocorrência de Pachycoris torridus (Scopoli, 1772) (Hemiptera: Scutelleridae) em Igaci (Alagoas), atacando a cultura de pinhão-manso, Jatropha curcas L. O inseto, até então não constatado na região, assume relevância econômica pela natureza dos danos, ocasionando infestação em 100 por cento das plantas.
The occurrence of Pachycoris torridus (Scopoli) (Hemiptera: Scutelleridae) in Igaci (in the state of Alagoas, Brazil), is observed attacking the physic nut (Jatropha curcas L.) The insect, until then not verified in the region, takes economic relevancy considering the nature of damage, causing infestation in 100 percent plants.
ABSTRACT
O pau-brasil (Caesalpinia echinata Lam.) tem grande valor cultural no Brasil e a sua propagação por sementes é dificultada pela rápida perda do poder germinativo delas. A estaquia pode ser usada para a produção de mudas de espécies florestais, principalmente quando existem algumas dificuldades de propagação por sementes. Este trabalho teve como objetivo caracterizar o efeito de concentrações e fontes de auxinas sobre o enraizamento de estacas de pau-brasil. Estacas com cerca de 12cm de comprimento e de um a dois pares de folhas foram tratadas na base com ácido indol butírico (AIB), ácido naftaleno acético (ANA) na forma líquida ou na forma de pó nas concentrações de 0, 1.250, 2.500, 5.000, 10.000mg L-1 ou mg Kg-1, respectivamente. As estacas foram transferidas para substrato contendo areia e mantidas sob nebulização (90-95 por cento UR). Aos 120 dias de estaquia, foram avaliados a mortalidade, a retenção foliar, a formação de calo e a percentagem de estacas enraizadas. As estacas apresentaram índices de sobrevivência de até 70 por cento. A formação de calos não foi relacionada com a concentração de auxinas utilizadas. O maior índice de enraizamento de estacas de pau-brasil, em torno de 16 por cento, foi resgistrada com a utilização do ácido indolbutírico (AIB) e do ácido naftalenoacético (ANA) na concentração 2.500mg L-1. Os altos índices de sobrevivência e os baixos índices de enraizamento sugerem que as estacas devem permanecer por mais tempo sob nebulização, a fim de induzir o seu processo de enraizamento.
The 'pau-brasil' tree (Caesalpinia echinata Lam.) have a high cultural value in Brazil and its seed propagation is very difficult because of its rapid losses of germination potential. Cuttings propagation has been considered as alternative method to propagate forest species that seed propagation is poor. The objectives of this study were to determine the effects of indole-3-butyric acid (IBA) and naphthalene acetic (NAA) acid on the adventitious root formation on stem cuttings of "pau-brasil". Cuttings with around 12cm length, with two pars of leaves, received a basal treatment of 0; 6,25; 12,50; 25 and 50mM IBA and NAA as solution form or 0, 1,250, 2,500, 5,000, 10,000mg Kg-1 as powder form. All cuttings were planted in cell trays containing sand and placed under greenhouse mist (90-95 percent relative humidity). After 120 days, cuttings were assessed for survival, foliar retention, callus formation and roots formation. There were high survival rate (up to 70 percent) of the cuttings. Callus formation was not correlated to auxin concentration. The utilization of liquid 25mM of IBA and NAA promoted the highest percentage of root formation, around 16 percent. The high survival rate associate with low percentage of root formation suggests that the cuttings may need longer time in greenhouse in order to stimulate root formation.