Nilton Rocha Leal

Brassinosteroid analogue affects the senescence in two papaya genotypes submitted to drought stress

Brassinosteroids (BS) application is associated with the increase of tolerance to some kinds of stresses, such as those induced by the infection of pathogens, temperature, salt and water deficiency. In this work, the influence of a spirostanic analogue of brassinosteroid (SAB) in the leaves of papaya Golden and UENF/CALIMAN 01 (UC 01) was tested to evaluate alterations in the content of chlorophyll in plants submitted to drought stress (DS). When plants were 70 d old, SAB was applied (0,1 mg L-1) for five consecutive days in half of the plants meant for the experiment. The treatments were: control irrigated (I), I with SAB (IB), DS and DS with SAB (DSB). The evaluated leaves were marked in accordance to the age: LEAF 1 (youngest expanded leaf), LEAF 2 (insertion immediately below LEAF 1) and LEAF 3 (insertion immediately below LEAF 2). The same leaves were used throughtout the experimental period. After the thirteenth day, the chlorophyll contents of DSB (Golden and UC 01) were always lesser than the treatment DS in LEAF 2. The irrigation was restarted in stressed plants on the fifteenth day, followed by new application of SAB (IB and DSB treatments). In Golden plants, DSB showed the lowest values of chlorophyll contents after re-watering, while in UC 01, differences in chlorophyll contents between treatments DS and DSB had not occurred. Alterations in Fv/Fm relation did not occur among the treatments during stress. In genotype UC 01, the irrigated plants showed minor values of Fv/Fm at the end of the experiment, whereas the plants submitted to DS presented increments in this relation in this same time. These results indicate that SAB might have contributed to accelerate the rate of leaf senescence of the oldest leaves of stressed plants, redistributing photoassimilates and other compounds for the youngest leaves.

Emissão de etileno e de CO2 em mamão 'Sunrise Solo' e 'Golden'

Papaya fruits of Sunrise Solo and Golden cultivars were stored at 10oC and 25oC. They were daily evaluated on C2H4 and CO2 production rates, by observing the peel color index increasing. The non increasing of the peel color index, during the 20 days of stored, was influenced by the appropriate refrigeration temperature whose inhibit papayas metabolism. It was noticed in the fourth and between the eighth and ninth day an increasing on respiration and ethylene rates, in the fruits stored at 25oC. The refrigeration decreased the respiration rate and papayas ethylene production, showing a metabolism reduction allowing fruits to present unripe appearance, even after 20 days of storage.

Padrão de ocorrência de doenças em mamão armazenado sob atmosfera controlada

ABSTRACT - The goal of this study was to evaluate the evolution of postharvest diseases on papaya storaged under controlled atmosphere, with3,0% of O 2 and 3,0 % or 6,0% of CO 2 , in relation to environment atmosphere (21,0% of O 2 e 0,00365% of CO 2 ), in simulation of refrigerated (10 o C)maritime transport and commercialization in European market, of ‘Sunrise Solo’ and ‘Golden’ papayas. The controlled atmosphere containg 3% of O 2 and 6% of CO 2 , promoted more fruit losses due the increase of postharvest diseases: anthracnosis, chocolat spot, stem-end-rot and, mainly, blackspot, on both cultivars. Probably, the increase of of CO 2 concentration, promoted injury in superficial cells, infection and tissue colonization . Index terms: Carica papaya L., Collethotrichum gloeosporioides Penz., controlled atmosphere, postharvest preservation, Asperisporium caricae (Speg.) Maubl. COMUNICACAO CIENTIFICA Com a adocao de sistemas de producao que minimizem aocorrencia de doencas em pos-colheita, e viavel exportar mamao, viamaritima, sob refrigeracao, uso de cera e atmosfera ambiente, para osfrutos produzidos na epoca mais seca e de temperaturas mais amenas doano, na regiao de Linhares-ES. O problema reside em se transferir omesmo pacote tecnologico para a exportacao de mamao produzido nosmeses mais quentes e umidos do ano. O uso de atmosfera controlada euma tecnologia disponivel para a resolucao do problema de contencaodo amadurecimento e reducao da ocorrencia de doencas pos-colheitaem mamao. Segundo Liberato & Tatagiba (2001), as principais doencaspos-colheita do mamao, Antracnose (

USO DE ATMOSFERA CONTROLADA PARA CONSERVAÇÃO PÓS-COLHEITA DO MAMÃO 'GOLDEN' 1

RESUMO - Frutos de mamoeiro ‘Golden’ colhidos no estadio 3 de maturacao foram armazenados sob controle de atmosfera (3%O 2 e 3%CO 2 , 3%O 2 e 6%CO 2 ou 8%CO 2 , 5%O 2 e 8%CO 2 ) e sob atmosfera ambiente (70% ou 90% U.R.), por 20 ou 25 dias, seguidos de mais 5 dias em atmosfera ambiente, a 10 o C. Apos 4 dias a 22 o C nao se verificaram muitas diferencas entre tratamentos, porem o maior teor de solidos soluveis em frutos armazenados sob 3%O 2 /3%CO 2 , e os maiores indices de maturidade nos frutos armazenados sob 3%O 2 /6%CO 2, por 20 dias, sugerem que novos estudos possam ser realizados adotando-se tais concentracoes. Termos para indexacao: Carica papaya L., atmosfera controlada, pos-colheita, exportacao. THE USE OF CONTROLLED ATMOSPHERE FOR POSTHARVEST CONSERVATION OF ‘GOLDEN’ PAPAYA