RESUMO A combinação de imagens aéreas multiespectrais e processamento computacional vem surgindo como uma das soluções utilizadas na agricultura de precisão para verificar o estado nutricional das plantas. Desse modo, o objetivo da pesquisa consiste em relacionar teor de nitrogênio e massa seca da parte aérea de plantas de milho (MS) com índices de vegetação obtidos por imagens aéreas multiespectrais (NDVIA e NDREA), e com o índice SPAD e o Greenseeker NDVI, no estádio vegetativo V6. Para tal, utilizou delineamento em blocos casualizados em esquema fatorial, sendo 6x4 (seis doses de nitrogênio na base e quatro diferentes alturas de voo), com três repetições. Os dados coletados foram submetidos à ANOVA pelo teste F (p ≤ 0,05) com posterior análise de regressão. O estudo revelou que é possível estimar massa seca da parte aérea das plantas de milho e teor de nitrogênio das folhas por meio do processamento de imagens aéreas multiespectrais, com utilização dos índices espectrais de vegetação NDVI e NDRE. Também, o clorofilômetro portátil SPAD (modelo SPAD-502) apresentou resultados promissores na estimativa do teor de nitrogênio, enquanto o sensor Greenseeker NDVI estimou com precisão o teor de nitrogênio e massa seca.

ABSTRACT The combination of multispectral aerial images and computational processing is emerging as one of the solutions used in precision agriculture to observe the nutritional status of plants. The objective of this study is therefore to associate the nitrogen content and dry weight of the aerial part of maize plants (DW) with the vegetation indices obtained by multispectral aerial images (NDVIA and NDREA), and with the SPAD index and the Greenseeker NDVI, in the vegetative stage V6. To this end, randomized blocks in a factorial scheme of 6x4 (six nitrogen doses at the base and four different flight altitudes) were used, with three replications. The collected data was submitted to ANOVA with the F test (p = 0,05) and subsequent regression analysis. The study showed that it is possible to estimate the dry weight of the aerial part of maize plants and the nitrogen content in the leaves through the processing of multispectral aerial images, using the NDVI and NDRE spectral vegetation indices. The portable chlorophyll meter SPAD (model SPAD-502) also had promissing results in the estimation of nitrogen content, while the Greenseeker NDVI sensor accurately estimated nitrogen content and dry weight.

Este trabalho teve como objetivo avaliar os atributos anatômicos e químicos da grama-missioneira-gigante à aplicação de 0, 62, 124, 186, 248 and 310m³ ha-1. Decorridos 83 dias do último corte e da aplicação do dejeto, as lâminas foliares foram coletadas, fixadas em FAA 70%, seccionadas, coradas, fotografadas e digitalizadas. Secções transversais das lâminas foliares foram avaliadas quanto à proporção das áreas de epiderme, tecido vascular lignificado + esclerênquima, tecido vascular não lignificado e parênquima, na região entre a quilha e o segundo maior feixe vascular, com sistema de processamento de imagem calibrado para 1mm pixel-1. Amostras de folhas foram coletadas e analisadas quanto ao teor de proteína bruta, fibra insolúvel em detergente ácido e fibra insolúvel em detergente neutro, pelo método de espectrometria de reflectância no infravermelho proximal. A aplicação de até 310m³ ha-1 do dejeto líquido de suíno aumentou os percentuais de proteína bruta, hemicelulose, parênquima e tecido vascular não lignificado, reduzindo os percentuais de fibra insolúvel em detergente ácido e tecido vascular lignificado + esclerênquima. A correlação de Pearson foi positiva entre o percentual de proteína bruta e tecido vascular não lignificado, e entre o percentual de fibra insolúvel em detergente ácido e tecido vascular lignificado + esclerênquima. O percentual de hemicelulose mostrou correlação positiva com epiderme, parênquima e tecido vascular não lignificado. Houve correlação negativa entre o percentual de fibra insolúvel em detergente ácido e epiderme, parênquima e tecido vascular não lignificado. O dejeto líquido de suínos, utilizado como fonte de nitrogênio, promove melhoria em atributos químicos e anatômicos, que afetam o valor nutritivo da grama-missioneira-gigante.

This study aimed to evaluate the chemical and anatomical attributes of leaves of giant missionary grass to application of 0, 62, 124, 186, 248 and 310m³ ha-1 of pig slurry. At 83 days after the last application of fertilizer, the leaf blades were collected, fixed in FAA 70%, sectioned, stained, photographed and digitalized. The transversal section of leaf blades were evaluated for proportion of epidermis, lignified vascular tissue + sclerenchyma, non-lignified vascular tissue and parenchyma with an image-processing system calibrated to 1mm pixel-1. Leaf samples were analyzed for crude protein, acid detergent fiber, neutral detergent fiber and hemicellulose content by near infrared reflectance spectroscopy. The pig slurry application up to 310m³ ha-1 significantly increased the percentage of crude protein, parenchyma, epidermis, non-lignified vascular tissue and hemicellulose, while decreasing the percentage of acid detergent fiber and lignified vascular tissue + sclerenchyma. The Pearson's correlation was positive between crude protein and non-lignified vascular tissue, and between acid detergent fiber and lignified vascular tissue + sclerenchyma. The percentage of hemicellulose was positively correlated with epidermis, parenchyma and non-lignified vascular tissue. A negative correlation between acid detergent fiber and epidermis, parenchyma and non-lignified vascular tissue was observed.

This study assessed the effect of successive applications of pig slurry on the dry matter (DM) production and the nitrogen use efficiency of giant missionary grass along two years. A total of 55, 110, 165, 220 and 275 m³ of pig slurry/ha/year were applied in order to supply 100, 200, 300, 400 and 500 kg of total N/ha/year, respectively. These treatments were compared with the ammonium nitrate (200 kg of N/ha/year) source of N and with a control (no nitrogen application). Annually, nitrogen was applied in four divided doses, after the cutting of forage grasses, which takes place five times a year. The total DM yield did not differ between years and increased linearly as a function of pig slurry application, ranging from 2,698 kg of DM/ha/year (control) to 11,371 kg of DM/ha/year (275 m³ of pig slurry/ha/year). There was an increment of 32.3 kg of DM/m³ of pig slurry/ha or 17.7 kg of DM/kg of N/ha. The highest average daily DM accumulation rate (66.8 kg of DM/ha/day) was achieved with the highest pig slurry rate, from February/2007 to April/2008. Nitrogen use efficiency did not differ across pig slurry rates (19.0 kg of DM/kg of N), but it was lower than that obtained with ammonium nitrate (30.3 kg of DM/kg of N). The efficiency index of pig slurry ranged from 0.52 to 0.72.

In this study, the phenotypic diversity of five accessions of giant missionary grass (Axonopus jesuiticus × A. scoparius) was evaluated by using morphophysiological traits. Accessions V 14337, V 14403, V 14404, V 14405 and V 14406 are hybrids derived from spontaneous crossing that occurred in Vale do Itajaí, Santa Catarina, Brazil. Plants were cultivated in greenhouse and evaluated at 60, 90, 120, 150, 180, 210 and 240 days of growth. Variation was observed for dry matter production, phenology and morphological traits, showing the possibility of selection. Flowering started at 210 days of growth and only in accessions V 14337 and V 14404. The Mahalanobis distance among accessions ranged from 35.64 (V 14403 and V 14405) to 183.38 (V 14337 and V 14405), and three groups were formed, based on 17 vegetative morphophysiological traits evaluated in plants with 180 days of growth: G1 (V 14403, V 14405), G2 (V 14406) and G3 (V 14337, V 14404). Group I presented the greatest dry matter production of stolon and aboveground, which were the traits with the largest relative contribution to genetic divergence, 38.67% and 38.31%, respectively. Accessions V 14403 and V 14405 are the most promising for agronomic evaluations that address their records as forage cultivars.

A produção de figos para consumo in natura, no sul do Brasil, é limitada pelas chuvas, que causam elevadas perdas por podridão. O uso da poda drástica, por sua vez, retarda o início da colheita e as baixas temperaturas impedem o crescimento e a maturação dos frutos a partir do início do outono. O cultivo da figueira está sendo estudado em ambiente protegido como tecnologia para ampliar o período de colheita, elevar a produtividade e minimizar perdas de frutos. Figueiras cv. Roxo de Valinhos foram cultivadas em ambiente protegido dotado de sistema de irrigação por gotejamento e submetidas a três épocas de podas, no segundo e terceiro ciclos vegetativos (15 de maio, 10 de agosto e 5 de outubro). As plantas foram conduzidas, no segundo ciclo, com 4 e 8 ramos por planta, espaçadas de 0,75 m x 1,90 m e de 1,50 m x 1,90 m, respectivamente, e, no terceiro ciclo, com 6 e 12 ramos por planta, nos respectivos espaçamentos. O delineamento experimental foi com quatro blocos casualizados, os tratamentos dispostos em faixa e duas plantas úteis por parcela. O cultivo do figo em ambiente protegido e com fertirrigação é tecnicamente viável na região de Passo Fundo - RS. A produção obtida é equivalente a 41 t.ha-1 e 43 t.ha-1 no segundo e terceiro ciclos de cultivo, respectivamente. A poda realizada no início de agosto e as plantas conduzidas com 8 a 12 ramos, no espaçamento de 1,50 m x 1,90 m, favoreceram a taxa de frutificação, a produção por planta e por área, além de maior período de colheita. O sistema de cultivo de figo em ambiente protegido foi eficiente em prevenir perdas por rachaduras e podridões de frutos.

Production of fresh fig (Carica ficus L.) fruits, in the south of Brazil, is limited by drastic rains that cause high losses of mature figs. Drastic pruning delays the beginning of the harvest and low temperatures hinder growth and maturation of fruits in the beginning of autumn. Fig-growing is being studied under protecting environment as technology to extend harvest period, raise productivity and to minimize fruit losses. Fig plants of variety Roxo de Valinhos were grown indoors under dripping irrigation system and three pruning periods (May 15th, August10th and October 5 th) at the second and the third vegetative cycles. Plants were lead with 4 and 8 branches per plant in the second cycle and spaced 0.75 m x 1.90 m and 1.50 m x 1.90 m apart, respectively, and with 6 and 12 branches per plant in the third vegetative cycle with the corresponding plant spacing. A randomized strip-plot design with four blocks was used with two plants per plot. Fig production under protecting environment with fertirrigation is technically viable in the Passo Fundo region in the state of Rio Grande do Sul. Fig productions were 43 and 41 t ha-1 in the second and the third years, respectively. The pruning carried through in the beginning of August and the plants led with 8 to 12 branches and spaced 1.50 m x 1.90 m apart favored the fruition rate, production per plant and per area and extended the harvest period. Fig growing under protecting environment was an efficient way of preventing losses from fruit splitting and decay.