Use of Physiological Parameters in Screening Drought Tolerance in Sugarcane Genotypes

The physiological response of four commercial sugarcane genotypes to water stress was evaluated by measuring the photochemical efficiency of the photosystem II (chlorophyll a fluorescence ratio, F v/F m), estimated chlorophyll content (SPAD unit), leaf temperature (LT) and leaf relative water content (RWC). A field trial was established in the subtropical area with well-watered and water-stressed genotypes, in completely randomized blocks with four replicates in a 4 × 2 × 3 factorial design (genotype × irrigation × evaluation date). Physiological measurements were done during a 90 day-period of formative stage of plants. The analysis of variance showed that the interaction of genotype × irrigation × evaluation date had a significant effect for three physiological markers tested, F v/F m, SPAD unit and RWC. Under non-stressed conditions, all genotypes showed similar responses for the four markers. Under water deficiency stress, two drought-tolerant genotypes, HOCP01-523 and TCP89-3505 displayed higher values for F v/F m, SPAD unit and RWC, and lower values for LT, and could be classified as tolerant. It is therefore possible to use these physiological water stress associated traits as scorable marker traits for selecting drought-tolerant sugarcane genotypes in future breeding programs. © 2011 Society for Sugar Research & Promotion.

Fluorescência da clorofila-a e variação da simetria como ferramentas de investigação de plantas sob estresse

Environmental disturbances in various systems and individuals can result in a tendency for fluctuating asymmetry, which consists of a non-directional deviation from symmetry of a bilateral structure in a normally distributed population. Individuals unable to exhibit plastic responses to developmental disorders that occur at random, either genetic or environmental, may exhibit slight deviations from symmetry in organs with bilateral structure such as leaves. Thus analyzing plants by the morphological pattern of symmetry of the leaves has become an effective tool to describe the developmental of plants under stress conditions. This study aimed to analyze if the pattern of symmetry can be used as a tool to investigate the stress level to which a plant is subjected, using ultraviolet-C radiation (UV-C) as source of stress. We determined the leaf symmetry deviations (sd), the average length (AL) and the maximum width of the lamina (MWL) and the fluorescence parameters of chlorophyll-a in leaves of young plants of G. max subjected to 0, 30, 60, 120 or 240 minutes per week of UV-C during four weeks, submitting the values to ANOVA and Tukey test (p <0.05). The results showed significant reductions in AL and MWL, significant increase in sd in leaves irradiated and a drop in potential quantum yield of photosystem II (PSII) and in the photosynthesis performance index (IP). The analysis of leaf symmetry showed high correlation with the stress level to which plants were submitted, being an important analysis to ascertain the fitness of the plant because it is a noninvasive method and easy to perform.

Respostas fisiológicas de cultivares de cana-de-açúcar a herbicidas seletivos

The use of selective herbicides to control weeds has caused different responses in cultivars of sugar cane, and some products affect physiological characteristics and reduce the photosynthetic activity. This study aimed to evaluate the physiological traits in cultivars of sugar cane under the effect of applying post-emergence herbicides. The test was developed in Jau, SP. The experimental design was randomized blocks in factorial scheme 5 x 4 (cultivar x herbicide) with four replications. SP81-3250, RB855156, RB855453, RB867515, IACSP95-5000 were grown in this studied. Herbicides clomazone (1200 g i.a.ha-1); commercial mixture of clomazone + ametryn (1000 + 1500 g i.a.ha-1) and ametryn (3000 g i.a.ha-1) and a control were applied at 30 days after planting. Cultivars IACSP95-5000 and RB867515 were less affected physiologically and can be considered selective to these herbicides. The application of clomazone and ametryn affected negatively the traits maximum photochemical efficiency of photosystem II (Fv/Fm), SPAD index and photosynthetic pigments, but the mixture of these herbicides caused higher reductions, indicating to be the more aggressive to the cultivars.

Tolerância à deficiência hídrica em cultivares de cana-de-açúcar avaliada por meio de variáveis morfofisiológicas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tolerância de Digitaria ciliaris, Digitaria horizontalis e Digitaria nuda à herbicidas usados em cana-de-açúcar

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da absorção do amicarbazone e intoxicação em cana-de-açúcar e plantas daninhas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Respostas de curto período das características fotossintéticas da alga vermelha Batrachospermum delicatulum a temperatura e irradiância

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação de parâmetros fisiológicos em cultivares de cana-de-açúcar submetidas ao déficit hídrico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento de clones de eucalipto em resposta a disponibilidade hídrica e adubação potássica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Divergência genética entre clones de eucalipto por caracteres biométricos e fisiológicos sob deficiência hídrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ocorrência de espécies do gênero Digitaria em canaviais do centro oeste paulista e susceptibilidade de alguns acessos à herbicidas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produtividade e qualidade da cana-de-açúcar sob doses de nitrogênio via fertirrigação subsuperficial por gotejamento

Pós-graduação em Agronomia (Agricultura) - FCA

Híbridos de eucalipto sob diferentes regimes hídricos em vasos e crescimento no campo

Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

Caracterização molecular de acessos de capim-colchão (Digitaria nuda) e resposta à ametrina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desempenho e divergência genética entre clones de Eucalyptus spp. em diferentes regimes de irrigação em casa de vegetação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)