VARIÁVEIS FISIOLÓGICAS DE ANTÚRIO CULTIVADO SOB DIFERENTES MALHAS DE SOMBREAMENTO

Change in the spectral quality radiation can have significant effect on the growth and development of a crop plant. The objective of the present research was to evaluate the growth and yield of Anthurium andraeanum cv. Apalai under different shading screens. For developing such research, micropopageted seedlings were planted in beds under four screens (blue, red, black and thermo-reflective) with 70% of shading. The experimental design was in complete block randomized, with four treatments and four repetitions. The evaluations were carried out when the inflorescences presented standard for marketing. Higher values of leaf area were observed in plants grown under screen black, followed by plants grown under thermo-reflective screen, red screen, and finally, blue. Differences in specific leaf area and in the ratio of chlorophyll a/chlorophyll b were no significant between treatments. Chlorophylls content, maximum fluorescence (Fm) and the ratio of variable to maximum fluorescence (Fv/Fm) were low under blue and red screen, while the initial fluorescence (Fo) was high. The chlorophyll content correlated positively with Fv/Fm (r 0,96; R2 0,95; P < 0,0001). The black screen provided the best condition for growth.Alteração na qualidade espectral da radiação pode ter efeito significativo no crescimento e desenvolvimento de uma cultura vegetal. O objetivo do presente trabalho foi avaliar o crescimento de Anthurium andraeanum cv. Apalai sob diferentes malhas de sombreamento. Para tal, mudas micropropagadas foram plantadas em canteiros sob quatro malhas (azul, vermelha, preta e termo-refletora) com 70% de sombreamento. O delineamento experimental foi em blocos casualizados, com quatro tratamentos e quatro repetições de quatro plantas. As avaliações foram conduzidas quando as inflorescências apresentaram padrão para comercialização. Valores mais altos de área foliar foram observados em plantas cultivadas sob malha preta, seguida de plantas cultivadas sob malha termo-refletora, vermelha e por último, azul. As diferenças na área foliar específica e na razão clorofila a/b entre os tratamentos não foram significativas. O teor de clorofilas, a fluorescência máxima (Fm) e a razão entre a fluorescência variável e máxima (Fv/Fm) foram baixos sob malha azul e vermelha, enquanto a fluorescência inicial (Fo) foi elevada. O teor de clorofilas correlacionou-se positivamente com a razão Fv/Fm (r 0,96; R2 0,95; P < 0,0001). A malha preta proporcionou a melhor condição para o crescimento

Estimation of beam at normal incidence using artificial neural network and comparing with statistical models

A irradiação direta na incidência normal (Hb) foi estimada utilizando Redes Neurais Artificiais (ANN2) para uma base de dados medida do período de 1996 a 2008 em Botucatu- Brasil, região com influência de queimadas agrícolas. A rede utilizada foi a Multilayer Perceptron (MLP), com o algoritmo de aprendizado backpropagation e termo momentum. A ANN2 foi comparada com um modelo estatístico de ajuste local (ME4) e dois modelos selecionados na literatura (ME5 e ME6). A variável de entrada foi o kt (transmissividade atmosférica da irradiação global). Os modelos foram avaliados por meio dos indicativos estatísticos: Mean Bias Error (MBE,MJm⁻²), Relative Mean Bias Error (rMBE,%), Root Mean Square Error (RMSE,MJm⁻²), Relative Root Mean Square Error (rRMSE,%) e d de Willmott. O desempenho de ANN2 é melhor que dos modelos estatísticos. A estimativa com ANN2 resultou: rRMSE=16,519% e d=0,980. O ME4 estimou com rRMSE=20,130% e d=0,971. Os ME5 e ME6 tiveram desempenho inferior ao ME4. O modelo ANN2 é recomendado como a primeira escolha para estimativa de Hb, seguido do modelo ME4.The direct irradiation at normal incidence (Hb) was estimated using Artificial Neural Networks (ANN2) to a database from 1996 to 2008 in Botucatu-Brazil, region with influence of agricultural burning. The network used was the Multilayer Perceptron (MLP), with the backpropagation algorithm and momentum term. The ANN2 was compared with a statistical model of local adjustment (ME4) and two models selected in the literature (ME5 and ME6). The input variable was the kt (atmospheric transmissivity of global radiation). The models were evaluated by means of statistical indicatives: Mean Bias Error (MBE,MJm⁻²), Relative Mean Bias Error (rMBE,%), Root Mean Square Error (RMSE,MJm⁻²), Relative Root Mean Square Error (rRMSE,%) and d Willmott. The ANN2 performance is better than statistical models. The estimate with ANN2 resulted: rRMSE=16.519% and d=0.980. The ME4 estimated with rRMSE=20.130% and d=0.971. The ME5 and ME6 had underperformed ME4. The ANN2 model is recommended as the first choice to estimate Hb, followed by ME4 model.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Sucker pruning management to change the harvest date in banana

In banana crop, sometimes it is necessary to manage seasonal production variations. The aim of the present study was to evaluate the effect of the selection of late successor sucker on the productive unit, compared to the selection of early successor sucker on the growth, harvest date and bunch mass of 'Prata' and 'Nanica' banana. The experimental design was completely randomized, with two treatments and ten replicates, considering two experiments, one for each cultivar. Treatments were conventional pruning (selection of early successor sucker) and modified pruning (selection of late successor sucker), which were established in September, with the destruction of the apical meristem of the successor sucker in modified pruning. The growth of the first and second suckers was quantified at intervals of about 60 days until the reproductive stage and bunch mass was determined. For both cultivars, pruning reduced the height and perimeter of the first successor sucker pseudostem and delayed the harvest date for at least 30 days, without reducing bunch mass. Regardless of sucker pruning management, production averages were 26.68 and 50.64 ton ha-1, respectively, for 'Prata' and 'Nanica' cultivars. For the second sucker, there was residual effect of pruning on the height of 'Nanica' cultivar, but not on production. Establishing the modified pruning is feasible for change harvest date of two cultivars, without&nbsp;increasing&nbsp;costs

Amostragem de plantas em cafeeiro para avaliação do estado nutricional

The foliar fertilization assists programs in order to obtain higher yields, however, it is essential to know the ideal number of plants to be sampled. The study aimed to determine in commercial coffee plantations, subjected to two water regimes, the number of plants to be sampled and estimate the sample error for the diagnosis of nutritional status of that culture. The work consisted of two studies where samples of leaves were collected in rainfed and irrigated farming. For both studies the completely randomized design, with four treatments and five repetitions that consisted of leaf collection in 5, 10, 20 and 40 coffee plants per sampling unit was used. So to keep the sampling error below 10 % for the macronutrient, leaf sampling five composite samples at 10 and 20 plants per sampling unit under irrigated and rainfed conditions, respectively, is sufficient. As for the content of micronutrients collecting 20 plants in systems except Cu and Mn requiring higher sampling five composite samples of 40 plants in rainfed systems are needed.A análise foliar auxilia os programas de adubação com o intuito de obter maiores produtividades, no entanto, é imprescindível conhecer o número adequado da amostra. Objetivou-se, no trabalho, determinar em lavouras comerciais de café, submetidas a dois regimes hídricos, o número de plantas a serem amostradas e estimar o erro amostral para a diagnose do estado nutricional dessa cultura. O trabalho foi composto por dois estudos, onde foram realizadas amostragens de folhas, em lavoura de sequeiro e irrigado. Para ambos os estudos foi utilizado o delineamento experimental inteiramente casualizado, com quatro tratamentos e cinco repetições, que constaram da coleta de folhas em 5, 10, 20 e 40 plantas de cafeeiro por unidade amostral. Assim, para manter o erro amostral menor que 10% para os teores de macronutrientes, a amostragem de folhas de cinco amostras, compostas em 10 e 20 plantas por unidade amostral nos sistemas irrigado e sequeiro, respectivamente, é suficiente. Já para o teor de micronutrientes é necessária coleta de 20 plantas nos sistemas, exceto o Cu e Mn que necessitam de amostragem superior a cinco amostras, compostas de 40 plantas, no sistema de sequeiro.