Physiological and productive performance of papaya plants irrigated in a semiarid environment

Papaya tree has great economic importance and potential of cultivation in semiarid environment. However, water scarcity in this region may inhibits photosynthetic activity and limit the production of this crop, being necessary to use strategies of irrigation management that rationalize water and allow the production of the plants without affecting photosynthetic activity. In this sense, this study aimed to evaluate the physiological and productive performance of papaya “Calimosa” under different water replacement rates in semiarid environment. Papaya plants were irrigated with four water replacement rates (50, 75, 100 and 125% ETo) from 30 days after transplant of seedlings to the experimental area.  At 10 months after transplant were realized evaluations of gas exchange and chlorophyll fluorescence, and at 12 months after transplant, it was started harvesting fruits to determine the yield. Water replacement rates significantly influenced the parameters of gas exchange of papaya with better results on rates of 125% ETo. However, application of water replacement rates of 100% ETo provide conditions adequate for the activity of gas exchange and better quantum efficiency of photosystem II, that contribute to fruit production in papaya. With rates less than 75% ETo occur drastic reductions in gas exchange, quantum efficiency of photosystem II, and fruit production of papaya, which impairs its cultivation in semiarid environments

Resistance to Fusarium sacchari associated with pokkah boeng in sugarcane genotypes in a semiarid environment in Brazil / Resistência à Fusarium sacchari associada à podridão do topo em genótipos de cana-de-açúcar em um ambiente semiárido do Brasil

A Pokkah boeng é uma doença causada por Fusarium sacchari que, embora ainda emergente, tem despertado atenção devido a sintomatologia observada em diversas regiões canavieiras do Brasil. Este estudo teve como objetivo avaliar a resistência de genótipos de cana-de-açúcar à F. sacchari nas condições ambientais de temperatura e umidade relativa preponderantes na região canavieira do estado do Piauí, Brasil. Inicialmente foi conduzido um ensaio no período chuvoso da região usando 16 clones de cana-de-açúcar que foram inoculados com F. sacchari via suspensão de esporos. Os níveis de resistência foram estabelecidos por scores (de 0-5) de uma escala diagramática e posterior classificação mediante o índice de severidade da doença (ISD). Posteriormente, quatro clones de cana-de-açúcar com os menores e quatro com os maiores ISD selecionados previamente no primeiro ensaio foram submetidos a um novo ensaio durante o período seco da região, utilizando-se a mesma metodologia do primeiro ensaio. Ficou demonstrado que a agressividade do fungo se torna mais expressiva em alguns genótipos, em geral, quando as médias de temperaturas estão em torno de 34 0C e umidade relativa do ar em torno de 75%. Assim, no período seco do ano, correspondente ao período de junho a novembro, a incidência desta doença é praticamente nula mesmo para os genótipos mais suscetíveis. Assim, nossos resultados demonstram que, apesar de haver inóculo do patógeno presente na região, o desenvolvimento de F. Sacchari não causa danos significativos à cana-de-açúcar em virtude das condições ambientais que limitam à doença

Physiology and yield of piel de sapo melon (Cucumis melo L.) under water deficit in semi-arid region, Brazil

Melon (Cucumis melo L.) is a crop of great socioeconomic importance in regions with semiarid climate, as found in Northeast Brazil. In this region water deficit is a usual condition as well as the main reduction factor of plant productivity. Due to this phenomenon, irrigation techniques are used to make available the amount of water needed for plant production. Therefore, this research evaluated the physiology and fruit production changes of ‘Juazeiro’ Piel de sapo melon plants under different water replacement rates. ‘Juazeiro’ melon was grown under four reference evapotranspiration replacement rates (40, 60, 80 and 100% of ETo) distributed randomly in blocks with 5 replicates. The plants were cultivated in the field, in an experimental area located in the Brazilian Northeast region, under hot and dry semiarid climatic conditions, and during the growing cycle the ‘Juazeiro’ hybrid melon plants were evaluated for leaf area, biomass accumulation, gas exchange, photochemical efficiency of photosystem PSII and production of fruits per plant. Application of water replacement rates of 100% ETo leads to highest growth, net photosynthesis, and fruit yield of 'Juazeiro' melon. Water replacement at 80% ETo can be used for ‘Juazeiro” melon under semiarid climatic conditions, but with small losses in fruit yield. Water replacement below 80% ETo leads to drastic reductions in growth, gas exchanges, quantum efficiency of photosystem II and fruit yield, which impairs melon production in semi-arid climate environments

Aspectos agronômicos do tomateiro “Caline Ipa 6” cultivado sob regimes hídricos em área do semiárido.

NNa Região Nordeste do Brasil, a instabilidade climática e a ocorrência de veranicos impossibilitam o cultivo adequado do tomate em todas as épocas do ano. Assim, faz-se necessário o uso da irrigação para suprir a demanda hídrica da cultura, porém tanto o excesso como o déficit de água no solo podem afetar a produção e a qualidade dos frutos. Nesse contexto, objetivou-se avaliar, com este trabalho, aspectos agronômicos do tomateiro “Caline IPA 6” cultivado sob diferentes taxas de reposição hídrica em área do semiárido paraibano. O experimento foi conduzido na área experimental do Setor de Fruticultura e Ecofisiologia Vegetal da Universidade Estadual da Paraíba (UEPB), campus de Catolé do Rocha (PB), onde 5 níveis de reposição hídrica foram estudados (50, 75, 100, 125 e 150% da evapotranspiração de referência - ETo) no delineamento em blocos ao acaso com 4 repetições e 9 plantas úteis por parcela. A ETo foi estimada com base no modelo de Penman-Monteith. Avaliaram-se variáveis agronômicas e produtivas das plantas de tomate. As lâminas de irrigação influenciaram significativamente as características analisadas, sendo constatado que os aspectos agronômicos do tomateiro “Caline IPA 6” são afetados positivamente com lâminas de irrigação acima de 100% da necessidade da cultura. Já a variação na reposição hídrica no consumo do tomateiro afeta os componentes de produção com maior intensidade no número de frutos e na produção por planta

Respostas da aplicação foliar de glicina betaína em cana-de-açúcar submetida a estresse hídrico e reidratação

The growth of sugarcane plants is greatly reduced due to the occurrence of drought stress, which ultimately affects production. Therefore, different strategies have been used to attenuate stress conditions, such as the exogenous application of glycine betaine. The objective of this work was to evaluate the growth rate and dry mass of sugarcane that received a glycine betaine application and was submitted to drought stress and rehydration. The experiment was carried out in a greenhouse with six treatments: G0I - plants without glycine betaine with adequate irrigation, G0E - plants without glycine betaine and drought stress, G1I - plants with an application of glycine betaine and adequate irrigation, G1E - plants with an application of glycine betaine and drought stress, G2I - plants with two applications of glycine betaine and adequate irrigation, G2E - plants with two applications of glycine betaine and drought stress. Six days after the stress, the plants were rehydrated. The relative growth rates of sugarcane plants decreased with the drought stress. However, these reductions were partially minimized with the foliar application of glycine betaine, mainly with the rehydration, with the relative growth rate decreasing by only 19% and 18.4%, respectively, in G1 and G2, while the reduction was 37.2% in G0. Glycine betaine also minimized reductions in total dry mass production under drought stress, with decreases of 5.8% and 5.9% in G1 and G2, respectively, while it was 15.1% in G0. The leaf application of glycine betaine improves the relative growth rate of sugarcane plants under drought stress, especially after rehydration, which decreases the negative effects of stress on dry mass production.O crescimento das plantas de cana-de-açúcar é bastante reduzido devido à ocorrência de déficit hídrico, o que acaba afetando a produção. Diante disso, vem sendo utilizadas diferentes estratégias para atenuar condições de estresse, como a aplicação exógena de glicina betaína. Com este trabalho, objetivou-se avaliar a taxa de crescimento e a massa seca de cana-de-açúcar aplicada glicina betaína, e submetida a déficit hídrico e reidratação. O experimento foi realizado em casa de vegetação com seis tratamentos: G0I - plantas sem glicina betaína com irrigação adequada, G0E - plantas sem glicina betaína e estresse hídrico, G1I - plantas com uma aplicação de glicina betaína e irrigação adequada, G1E - plantas com uma aplicação de glicina betaína e estresse hídrico, G2I - plantas com duas aplicações de glicina betaína e irrigação adequada, G2E - plantas com duas aplicações de glicina betaína e estresse hídrico. Aos seis dias após o estresse as plantas foram reidratadas. As taxas relativas de crescimento das plantas de cana-de-açúcar reduziram com o estresse hídrico. No entanto, estas reduções foram minimizadas com a aplicação foliar de glicina betaína, principalmente, com a reidratação em que a taxa relativa de crescimento reduziu apenas 19 e 18,4%, respectivamente, em G1 e G2, enquanto em G0 a redução foi de 37,2%. A glicina betaína também minimizou as reduções na produção de massa seca total sob estresse hídrico, com reduções de 5,8 e 5,9% em G1 e G2, respectivamente, enquanto em G0 foi de 15,1%. A aplicação foliar de glicina betaína melhora a taxa relativa de crescimento de plantas de cana-de-açúcar sob estresse hídrico, sobretudo após a reidratação o que diminui os efeitos negativos do estresse sobre a produção de massa seca

Agricultural economic efficiency of the consortium castor and peanut in semiarid area of Paraiba

A mamoneira é de grande importância à agricultura do semiárido brasileiro por ser de fácil cultivo, tolerante à seca e possuir características benéficas para cultivo associado a outras culturas. Assim, o objetivo deste estudo foi avaliar os aspectos agroeconômicos da consorciação mamona e amendoim sob irrigação em condições de Semiárido. O estudo foi realizado na área experimental do Setor de Fruticultura e Ecofisiologia Vegetal, Campus IV, da Universidade Estadual da Paraíba, localizado no município de Catolé do Rocha, PB. O período de estudo foi de junho a dezembro de 2011, envolvendo as culturas de mamona BRS Energia e amendoim BR-1 , em sistemas consorciados e isolados. O delineamento utilizado foi em blocos ao acaso com quatro repetições e oito tratamentos, sendo: T1 Mamona solteira no espaçamento de 2,0 m x 0,5 m; T2 Amendoim solteiro no espaçamento de 2,0 m x 0,2 m; T3 Amendoim solteiro no espaçamento de 1,0 m x 0,2 m; T4 Consórcio mamona e amendoim semeados no mesmo dia; T5 Consórcio mamona e amendoim semeado 10 dias após (M + A10); T6 Consórcio mamona e amendoim, este semeado 15 dias após a mamona (M + A15); T7 Consórcio mamona e amendoim semeado 20 dias após (M + A20); e T8 Consórcio mamona e amendoim semeado 25 dias após (M + A25). As melhores taxas de crescimento e área foliar da mamoneira BRS Energia são obtidas ao semear o amendoim BR-1 em intervalo de 20 a 25 dias após a mamona. Há maior produção de vagens de amendoim quando a semeadura é feita entre 10 e 15 dias após a da mamona. As épocas mais tardias de semeadura do amendoim permite alcançar melhores rendimentos de grãos de mamona em sistema consorciado. Em consórcio, o amendoim é mais eficiente biologicamente e maiores rendimentos são obtidos quando semeado 20 dias após a mamona.The castor bean has great importance to the brazilian semiarid region and it can be easy to grow, tolerant to drought and has beneficial features to production associated with other cultures. Thus, the objective of this study was to evaluate agricultural economic aspects intercropping castor and peanut under irrigated conditions in semiarid. The experiment was accomplished at the experimental Sector Fruit and Plant Ecophysiology, IV Campus, State University of Paraiba (UEPB), located in the municipality of Catolé do Rocha, PB. The study period was from June to December 2011, using the cultivation of castor bean BRS Energy and peanuts 'BR-1', in intercropping systems and isolated. The experimental design was in randomized blocks with four replications and eight treatments: T1- Single castor bean spaced in 2,0 m x 0,5 m, T2- Single peanut in spacing of 2,0 m x 0,2 m, T3- Single peanut spaced in 1,0 m x 0,2 m, T4- Consortium castor bean and peanuts sown on the same day, T5- Consortium castor bean and peanuts sown 10 days after the castor bean (M + A10), T6- Consortium castor bean and peanut, sown 15 days after castor bean (M + A15), T7- Consortium castor bean and peanut sown 20 days after the castor bean (M + A20), T8- Consortium castor bean and peanut sown 25 days after the castor bean (M + A25). The best growth rates and leaf area of the castor bean BRS Energy are obtained when the peanuts BR-1 was sown from 20 to 25 days after the castor bean. The production of peanut pods increased when was sown between 10 and 15 days after the castor bean. The later periods of sowing of peanuts will provide better yields of castor bean in intercropping system. In the consortium, the peanut is biologically more efficient and higher yields are obtained when sown 20 days after the castor bean

Photosynthetic efficiency and production of cowpea cultivars under deficit irrigation

Cowpea is a crop with great economic, social and food importance in semi-arid regions, but its production is drastically reduced by the water deficit in these regions, requiring better management strategies that allow the crop’s production. This study therefore aimed to evaluate the photosynthetic efficiency and production of cowpea cultivars under deficit irrigation replacement levels. The experiment tested three cowpea genotypes (G1 = ‘BRS Aracé’, G2 = ‘BR 17 Gurguéia’ and G3 = ‘BRS Marataoã’) and four irrigation depths (40, 60, 80 and 100% of ETc), resulting in a 3 x 4 factorial scheme, arranged in randomized complete blocks design with four replicates. During the experiment, the gas exchanges, chlorophyll a fluorescence and production of the cowpea genotypes under deficit irrigation were evaluated. Carbon fixation in the photosynthetic metabolism of cowpea plants was reduced by accentuated water deficit, regardless of the genotype. The low stress severity was indicated by the lack of effects on chlorophyll fluorescence, indicating that the reduction in the rate of carbon assimilation was due to the stomatal effects. The irrigation with 80% of ETc can be used in the cultivation of the respective cultivars, but with small losses in the production. Among the genotypes, ‘BRS Marataoã’ stands out with respect to yield, with higher values for weight of pods and green beans

Viabilidade agroeconômica do consórcio mamona e amendoim em área do semiárido brasileiro

Abstract Castor bean (Ricinus communis L.) is important an important plant due to its easily cultivation, drought tolerance and beneficial adaptation combined to other food crops, like peanuts (Arachis hypogaea L.). Castor is an interesting option to increase producer income and improve land use efficiency in intercropping. This research was carried out to evaluate advantages, yield, cost of production and profitability in the intercropping castor/peanut as a function of sowing time. The castor genotype (BRS Energia) and peanut (BR-1) were grown in monocropping and intercropping systems. A randomized block design was used with four replications and eight treatments, being five treatments in intercropping (castor + peanut) varying the interval sowing of peanut regarding to the sowing of castor (0, 10, 15, 20 and 25 days), and three treatments with castor and peanut cultivated in monocropping. The yield of both crops as well the profitability of the cropping systems, cost of production and competitive rates were evaluated. The grain yield of both intercropped crops was affected when the sowing time was expanded. There was better castor yield in longer sowing time compared to peanut. In this case, intercropping was more advantageous to castorbean when peanut was sown between 15 and 20 days late with better competitive ability of castor. The larger total operational cost of US$ 1452.11 ha -1 observed in peanut monocropping spaced 1.0 m × 0.2 m mainly due to higher material expenses and inputs, compared to intercropped system. The intercropping castor/peanut in the spaces 2.0 × 0.5 (castor) and 2.0 × 0.2 (peanut) under Brazilian semiarid region can be suitable and profitable when peanut is sown 20 days after castor