Liana Hilda Golin Mengarda

Morphological and physiological adjustments of Brazilwood (Caesalpinia echinata Lam.) to direct solar radiation

This study aimed to characterize the alarm and resistance phases of stress of Caesalpinia echinata under intense irradiance in order to better define its position on forest succession. The alarm phase was identified by rapid reduction in the maximum quantum yield of PSII primary photochemical reactions (ΦP0 = FV/FM) and Performance Index (PIABS) followed by total leaf abscission in the first week of exposure to direct sunlight. The new leaves grown showed recovery of chlorophyll a parameters, increase in blade thickness, elongation of the palisade and spongy parenchymas, higher water content, and reduction of specific leaf area. These changes were associated with the osmoprotector of sucrose and antioxidative of raffinose effects, which indicate an efficient adjustment system to intense irradiance in the resistance phase of stress. However, the continuous decrease in photosynthetic pigments in the resistance phase combined with the photodamage in the fluorescence of Chl a and total abscission of leaves in the alarm phase are strong indications that C. echinata is a shade and late or climax species in forest succession.

Emergência e vigor de mudas de genótipos de mamoeiro em função da irradiância

Luminosity influences seed emergence in the initial development of papaya plants, being necessary the identification of the ideal irradiance level for plantule establishment and formation of vigorous seedlings. This study aimed to evaluate the seed emergence and seedlings vigor of four papaya genotypes, under different irradiance levels. Carica papaya L. seeds, from the Caliman 01 hybrid, Golden THB , triple hybrid and JS12 x Waimanalo hybrid genotypes , were evaluated under four irradiance levels (60 m mol m -2 s -1 , 130 m mol m -2 s -1 , 580 m mol m -2 s -1 and 1,200 m mol m -2 s -1 ). A completely randomized design, in a 4x4 split-plot scheme , with four replications, was used . The emergence percentage and speed index were evaluated . The seedlings were measured at 45 and 120 days after sowing (DAS), concerning root and shoot length and dry matter , being calculated the root/shoot ratio and absolute growth rate at 120 DAS . The full sun affected emergence , while the low irradiance affected seedling growth. The intermediate irradiance (130 m mol m -2 s -1 and 580 m mol m -2 s -1 ) was more suitable to the development of papaya seedlings up to 120 DAS. The Golden THB genotype was more sensitive to high irradiance, while the Caliman 01 and JS12 x Waimanalo hybrids tolerated the full sun condition .

Efeito de liberadores de óxido nítrico na qualidade fisiológica de sementes de repolho sob salinidade

Studies with Brassica sp. demonstrate that salt stress affects the seed physiological quality and vigor. Thus the search for substances that minimize the effects caused by salt stress during germination are of great importance. The aim of this study was to verify the action of nitric oxide-releasing substances during germination of cabbage grown under salt stress. The seeds were pre-soaked in solutions of potassium nitrate (KNO3) and sodium nitroprussiato (SNP) at concentrations of zero, 0.01, 0.10, 1.00 and 10.00 mmol L-1 for 30 minutes. Then the seeds were germinated in Petri dishes lined with moistened paper germitest with NaCl solution at potentials of 0.0, -0.6 and -1.2 MPa, evaluated the germination and seedling development. There was no germination in osmotic potential of -1.2 MPa. The potential of -0.6 MPa reduced germination and seedling growth of cabbage. The results suggest that there was positive action of KNO3 and SNP at 0.01 mmol L-1, reversing the stress caused by salinity (-0.6 MPa of NaCl).

QUALIDADE FISIOLÓGICA DE SEMENTES DE REPOLHO DE ALTO E BAIXO VIGOR SOB ESTRESSE SALINO

Objetivou-se, com este trabalho, avaliar a qualidade fisiologica de lotes de sementes de repolho de alto e baixo vigor sob salinidade. A viabilidade dos lotes foi avaliada pelo teste de tetrazolio, sendo caracterizados como lote 1 – alto vigor, e lote 2 – baixo vigor. As sementes foram submetidas a dois sais, NaCl e KCl, em diferentes potenciais osmoticos: 0,0 (controle); -0,2; -0,4; -0,6; -0,8 e -1,0 MPa. A semeadura foi feita em placas de Petri forradas com papel germitest, mantidas em câmara de germinacao tipo BOD regulada a temperatura de 25 °C. As caracteristicas avaliadas foram: germinacao, indice de velocidade de germinacao, massa fresca, massa seca, comprimento da parte aerea e da raiz das plântulas. Reducao no potencial osmotico reduz a germinacao e afeta negativamente o vigor das sementes de repolho de ambos os lotes; o KCl e mais agressivo, afetando a germinacao e o desenvolvimento das plântulas em concentracoes menores que o NaCl. As sementes de repolho com alto vigor apresentam menor sensibilidade ao estresse salino.

EFEITO DO AIB E DO ÁCIDO BÓRICO NA FORMAÇÃO E ENRAIZAMENTO DE BROTOS LATERAIS EM ESTACAS DE ORQUÍDEAS

Objetivou-se avaliar o efeito do AIB e do acido borico na formacao e no enraizamento de brotos em estacas das orquideas Arundina bambusifolia, Dendrobium nobile, e Oncidium sp. Apos sofrerem assepsia em hipoclorito de sodio 1% por 1 minuto, e enxague em agua destilada, as estacas foram imersas por 1 min em diferentes concentracoes de AIB (0, 400, 800, 1200 mg mL-1), associado ou nao ao tratamento previo com acido borico (100 ug mL-1). As estacas foram dispostas em tubetes contendo substrato comercial, mantidos em casa de vegetacao com nebulizacao. A avaliacao da porcentagem de brotacao, enraizamento, sobrevivencia, numero e comprimento dos brotos e raizes foi realizada aos 90 dias. O pre-tratamento com de acido borico induziu a maior porcentagem de mortalidade e menor enraizamento, nao sendo indicado na propagacao por estaquia das orquideas em estudo. Sem tratamento com acido borico, para A. bambusifolia, a concetracao de 400 mg L-1 de AIB promoveu maior porcentagem de brotacao e maior comprimento dos brotos. Para D. nobile as melhores respostas quanto as brotacoes foram obtidas sem nenhum tratamento, enquanto a concentracao de 1200 mg L-1 de AIB promoveu maior enraizamento. Oncidium sp. nao respondeu adequadamente a propagacao por estaquia.

Qualidade de sementes e desenvolvimento inicial de plântulas de pimenta malagueta e sua relação com a posição de coleta de frutos

The objective of this study was to evaluate the relationship between the collection position of fruits from the malagueta pepper plant and seed quality and initial seedling development. The seeds were obtained from fruits collected at different positions in the canopy (C) and branches (R): 1 - apical, 2 - median, and 3 - basal. The following evaluations were made: water content, seed weight (PMS), number of seeds per kilogram, seed size (1ength , width and thickness), germination and vigor, according to the germination speed index (IVG), the average time of germination (TMG), root and seedling length, and the fresh and dry weights of seedlings 28 days after sowing. Seeds from fruits collected from the basal and median positions of the canopy, and base of branches (C2R3 and C3R3) had a higher PMS, associated with a greater seed length and width. These treatments also showed a higher germination percentage, germination speed index and lower mean germination time. Besides the higher vigor, seeds from fruits collected in the basal region (C3R3) show greater plant development for root length and fresh and dry weight of the seedlings.

EMBEBIÇÃO, OSMOCONDICIONAMENTO E VIABILIDADE DE SEMENTES DE Apuleia leiocarpa (VOGEL.) J. F. MACBR.

The aim of this work was to characterize the imbibition and to evaluate the physiological quality of Apuleia leiocarpa seeds after priming. It was done the immersion of intact and scarified seeds in distilled water for 96 hours. In the study of priming, the scarified seeds were separate on three lots (L1, L2, L3), the first has been conditioned in distilled water only (control), the second and the third were osmoconditioned in PEG 6000, at potentials of -0.4 and -0.8 MPa, respectively, for 10 hours. Then, the seeds were placed in plastic bags and kept under controlled temperature of 3°C ± 1. Sowing was performed after 0, 30, 60, 90 and 120 days of priming. Seed quality was evaluated by: germination percentage, germination speed index, relative frequency of germination, root length, shoot length, and seedling dry weight. The seed imbibition of Apuleia leiocarpa follows the three-phase model of water absorption, starting after three hours and culminates with the primary root protrusion after 72 hours. The primed seeds in -0.8 MPa of PEG maintained the physiological quality of seeds, while seeds primed in water and -0.4 MPa of PEG linearly reduced the percentage and speed of germination, the length and the dry weight of seedlings.

PERFORMANCE OF GENERATIONS OF UENF/CALIMAN 01 PAPAYA AND CORRELATIONS BETWEEN GERMINATION, VEGETATIVE AND REPRODUCTIVE DEVELOPMENT

The aim of this study was to characterize the seeds quality and the plant development of F1 and F2 generations of hybrid UENF/Caliman 01 papaya, and the relations between the physic-chemical and physiological quality of seeds, vegetative and reproductive development of plants in the field for 360 days, and fruit quality. The relative contribution (Cr %) to the genetic divergence for each characteristic was estimated. For those with higher importance for each group (Cr = 25%), the Pearson correlation and the canonical correlation analysis were applied. The F1 seeds showed higher physic-chemical and physiological quality, with greater length (0.55 cm), sugar and lipid levels (5.13 and 11.58 mg g-1, respectively), germination and normal seedlings percentages (94 and 98.31%, respectively). The F2 plants showed higher stem diameter (81.08 mm), fruits insertion height (184.8 cm) and fruits number (11.73). It was observed that higher levels of lipid in the seeds were associated with lower fruits number. Lower levels of sugar and lipid of the seeds and lower speed germination index were associated with lower survival. Thus, seed quality is associated with survival of hybrid UENF/Caliman 01 papaya plants in the field, but it does not have relation with the vegetative and reproductive development of plants.

TESTES DE DETERIORAÇÃO CONTROLADA E DE ENVELHECIMENTO ACELERADO NA AVALIAÇÃO DA QUALIDADE FISIOLÓGICA DE SEMENTES DE REPOLHO

O objetivo do trabalho foi verificar a eficiencia dos testes de deterioracao controlada e envelhecimento acelerado na diferenciacao da qualidade fisiologica de sementes de repolho, cvs. “quatro estacoes” e “sessenta dias”. As sementes foram submetidas aos testes de deterioracao controlada com teores de agua de 16, 18, 20 e 22%, a 45 oC durante 24 h, e ao teste de envelhecimento acelerado (45 oC por 48 h). Em seguida, as sementes foram dispostas em placas de Petri, acondicionadas em BOD com temperatura constante de 30 oC, sendo avaliadas quanto a germinacao e ao vigor. Os testes de envelhecimento acelerado e deterioracao controlada sao eficientes para identificar diferentes niveis de vigor das sementes dos cultivares de repolho “quatro estacoes” e “sessenta dias”, principalmente por meio da analise do indice de velocidade de geminacao.