Aspectos fisiológicos e bioquímicos da mandioca cultivada sob deficiência hídrica em diferentes fases de desenvolvimento
Data
2017-05-26
Autores
Pereira, Laís Fernanda Melo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Essa pesquisa teve como objetivo avaliar as características fisiológicas, bioquímicas e os componentes da produção da mandioca de mesa IAC 576-70 sob deficiência hídrica em diferentes fases fenológicas da cultura. O experimento foi conduzido em cultivo protegido, em delineamento inteiramente casualizado e esquema fatorial 3x3, constituído por três fases fenológicas (de 90 a 180; de 180 a 270 e de 270 a 360 dias após o plantio, DAP) e três tensões de água no solo (-10, -40 e -70 kPa), com cinco repetições. As manivas-sementes foram plantadas em caixas com 0,30 m3 de solo e a umidade do solo foi monitorada por tensiômetros, mantendo-se o solo na capacidade de campo até o início dos tratamentos. As características fisiológicas e bioquímicas foram descritas apenas na fase de 90 a 180 DAP, pois a perda natural de folhas no período do inverno na região comprometeu as avaliações nas demais fases. Aos 135 DAP a deficiência hídrica aumentou 42,9% o teor de clorofila total nas plantas sob tensão de -70 kPa. O potencial da água, o teor relativo de água e o extravasamento de eletrólitos nas folhas não foram alterados pelas tensões de água no solo. Houve acréscimo de 16,0% na densidade estomática foliar nas tensões de -40 e -70 kPa, enquanto que a eficiência quântica efetiva do fotossintema II e a taxa de transporte de elétrons foram reduzidas. As plantas sob as menores tensões de água no solo aumentaram 15,4% os teores de açúcares solúveis nas folhas. As atividades das enzimas antioxidantes foram mais acentuadas aos 180 DAP, de modo que os teores de peróxido de hidrogênio não diferiram entre os tratamentos. A tensão de -70 kPa ocasionou aumento de 22,6% nos teores de ácido malondialdeído nas folhas aos 135 DAP. A deficiência hídrica entre 90 e 180 DAP reduziu 60% as massas de matéria seca da parte aérea e da raiz, ocasionando perdas de até 75,6% na produção total de raiz. A limitação hídrica entre 180 a 270 DAP não alterou a massa de matéria seca da planta, o número de raiz não comercial, o índice de colheita, o teor de amido e a produção de raiz. As plantas sob deficiência hídrica entre 270 a 360 DAP reduzem em 32,5% a produção total de raiz tuberosa. A deficiência hídrica efeta o desenvolvimento das plantas de mandioca na fase de desenvolvimento dos ramos e folhas.
This research aimed to evaluate the physiological and biochemical characteristics and yield components of sweet cassava plants IAC 576-70 under water deficit in different phenological phases of the crop. The experiment was carried out in a completely randomized design and factorial scheme 3 x 3, consisting of three phenological stages (90 to 180, 180 to 270 and 270 to 360 days after planting DAP), and three soil water tension (-10, -40 and -70 kPa), with five replicates. The stem cuttings were planted in boxes with 0.30 m3 of soil and the soil moisture was monitored by tensiometers, keeping the soil in the field capacity until the beginning of the treatments. The physiological and biochemical characteristics were described only in the phenological phase 90 to 180 DAP, because the natural loss of leaves in the winter period in the region compromised the evaluations in the other phases. At 135 DAP the water deficit increased by 42.9% the total chlorophyll content in plants under tension of -70 kPa. The water potential, relative water content and electrolyte leakage in the leaf were not altered by soil water tension. There was an increase of 16.0% in leaf stomatal density under tensions of -40 and -70 kPa, while the effective quantum efficiency of photosystem II and the rate of electron transport were reduced. The plants under the tensions of -40 and -70 kPa increased the soluble sugar content of the leaves by 15.4%. The activities of antioxidant enzymes were more accentuated at 180 DAP, so that the levels of hydrogen peroxide did not differ between treatments. The tension of -70 kPa caused an increase of 22.6% in malondialdehyde acid content in the leaves at 135 DAP. The water deficit between 90 and 180 DAP reduced the dry matter masses of the aerial part and the tuberous root by 60%, causing losses of up to 75.6% in total root yield. The water limitation between 180 and 270 DAP did not change the dry matter mass of the plant, number of non-commercial root, harvest index, starch content and root yield. Plants under water deficit between 270 and 360 DAP reduce total tuberous root production by 32.5%. The water deficit effects the development of cassava plants in the development stage of the branches and leaves.
This research aimed to evaluate the physiological and biochemical characteristics and yield components of sweet cassava plants IAC 576-70 under water deficit in different phenological phases of the crop. The experiment was carried out in a completely randomized design and factorial scheme 3 x 3, consisting of three phenological stages (90 to 180, 180 to 270 and 270 to 360 days after planting DAP), and three soil water tension (-10, -40 and -70 kPa), with five replicates. The stem cuttings were planted in boxes with 0.30 m3 of soil and the soil moisture was monitored by tensiometers, keeping the soil in the field capacity until the beginning of the treatments. The physiological and biochemical characteristics were described only in the phenological phase 90 to 180 DAP, because the natural loss of leaves in the winter period in the region compromised the evaluations in the other phases. At 135 DAP the water deficit increased by 42.9% the total chlorophyll content in plants under tension of -70 kPa. The water potential, relative water content and electrolyte leakage in the leaf were not altered by soil water tension. There was an increase of 16.0% in leaf stomatal density under tensions of -40 and -70 kPa, while the effective quantum efficiency of photosystem II and the rate of electron transport were reduced. The plants under the tensions of -40 and -70 kPa increased the soluble sugar content of the leaves by 15.4%. The activities of antioxidant enzymes were more accentuated at 180 DAP, so that the levels of hydrogen peroxide did not differ between treatments. The tension of -70 kPa caused an increase of 22.6% in malondialdehyde acid content in the leaves at 135 DAP. The water deficit between 90 and 180 DAP reduced the dry matter masses of the aerial part and the tuberous root by 60%, causing losses of up to 75.6% in total root yield. The water limitation between 180 and 270 DAP did not change the dry matter mass of the plant, number of non-commercial root, harvest index, starch content and root yield. Plants under water deficit between 270 and 360 DAP reduce total tuberous root production by 32.5%. The water deficit effects the development of cassava plants in the development stage of the branches and leaves.
Descrição
Palavras-chave
Manihot esculenta Crantz, Seca, Fluorescência da clorofila, Ajuste osmótico, Enzimas antioxidantes, Produção, Drought, Chlorophyll fluorescence, Osmotic adjustment, Antioxidant enzymes, Yield