Scielo RSS <![CDATA[Bragantia]]> vol. 75 num. 2 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[Ecophysiological leaf traits of native and exotic palm tree species under semi-arid conditions]]> ABSTRACT The main goal of this study was to evaluate the performance of two palm species under semi-arid conditions during the rainy and dry periods: the semi-arid native Syagrus coronata and a native to tropical America, Acrocomia aculeata. The leaf water potential, gas exchange, leaf soluble sugars, starch, free amino acids, total soluble protein content and morphological traits were measured. The highest leaf water potential and CO2 assimilation values in both species were achieved during the rainy period. In response to the low soil moisture content during the dry period, gas exchange decreased 72 and 92% in S. coronata and A. aculeata, respectively, when compared with values from rainy period. As evergreen plants, both species maintained intact leaf photosynthetic pigment contents during the rainy and dry periods. Other important traits for drought tolerance are larger adaxial surface hypoderm and cuticle found in both species with higher stomatal density on the abaxial leaf surface. When comparing the species, S. coronata exhibited lower sensitivity to low water availability, showing higher CO2assimilation and water use efficiency. <![CDATA[Comparação de testadores na seleção de famílias S<sub>3</sub> obtidas da variedade UENF-14 de milho-pipoca]]> ABSTRACT The use of topcross has proven to be an interesting option for the maize crop; however, for the popcorn, there is little information about the choice of the appropriate tester. In this context, this study aimed to analyze four testers including two open pollinated varieties(BRS Angela and UENF-14), one topcross hybrid (IAC125) and a line (P2), to evaluate the combining ability of 50 S3 families of popcorn, obtained from the UENF-14 variety. Popcorn families were evaluated for grain yield (GY) and popping expansion (PE). The estimates of general and specific combining abilities were obtained and the discrimination of each tester through differentiation index was carried out. The testers BRS Angela (for GY) and IAC 125 (for PE) were the most adequate, when combined with the best S3 families derived from UENF-14, for the production of popcorn hybrids for the Northern and Northwestern Fluminense Regions.<hr/>RESUMO O uso de topcross vem se mostrando uma opção interessante para a cultura do milho; entretanto, para o milho-pipoca, há pouca informação sobre a escolha do testador adequado. Nesse contexto, este estudo teve como objetivo analisar quatro testadores, sendo duas variedades de polinização aberta (BRS Angela e UENF-14), um híbrido topcross (IAC 125) e uma linhagem (P2), visando avaliar a capacidade combinatória de 50 famílias S3 de milho-pipoca, obtidas a partir da variedade UENF-14. Avaliou-se o rendimento de grãos (RG) e capacidade de expansão (CE). Obtiveram-se as estimativas das capacidades geral e específica de combinação, bem como efetuou-se a discriminação de cada testador por meio de índice de diferenciação. Os testadores BRS Angela (para RG) e IAC 125 (para CE) foram os que se destacaram, quando combinados com as melhores famílias S3derivadas da variedade UENF-14, para produção de híbridos de milho-pipoca para as Regiões Norte e Noroeste Fluminense. <![CDATA[Viability of pollen grains of tetraploid banana]]> ABSTRACT Obtaining banana tetraploid cultivars from triploid strains results in total or partial reestablishment of fertility, allowing the occurrence of some fruits with seeds, a feature that is undesirable from a marketing perspective. The objective of this study was to assess the viability of pollen of 12 banana tetraploid hybrids (AAAB) by means of in vitro germination and two histochemical tests (acetocarmine and 2,3,5-triphenyltetrazolium chloride). The pollen tube growth was evaluated by germinating grains in three culture media — M1: 0.03% Ca(NO3)∙4H2O, 0.02% Mg(SO4)∙7H2O, 0.01% KNO3, 0.01% H3BO3 and 15% sucrose; M2: 0.03% Ca(NO3)∙4H2O, 0.01% KNO3, 0.01% H3BO3 and 10% sucrose; and M3: 0.015% H3BO3, 0.045% Ca3(PO4)2 and 25% sucrose. The acetocarmine staining indicated high viability (above 80%), except for the genotypes YB42-17 and Caprichosa, which were 76 and 70%, respectively. However, the in vitro germination rate was lower than 50% for all the genotypes, except for the hybrids YB42-17 (M1) and YB42-47 (M1). The medium M1 provided the greatest germination percentage and pollen tube growth. Among the genotypes assessed, YB42-47 presented the highest germination rate (61.5%) and tube length (5.0 mm). On the other hand, the Vitória cultivar had the lowest germination percentage (8.2%) in medium M1. Studies of meiosis can shed more light on the differences observed in the evaluated tetraploids, since meiotic irregularities can affect pollen viability. <![CDATA[Avaliação de genótipos de feijoeiro quanto à eficiência do uso do fósforo em Latossolo Vermelho Eutrófico]]> ABSTRACT Common bean is one of the most important legumes in Latin America, mostly grown in soils with low phosphorus (P) availability. Thus, this study aimed to evaluate the responses of 20 bean genotypes to P deficiency. The experiment was a completely randomized design in a 2 × 20 factorial arrangement; the first factor consisted of P levels and the second factor, of 20 bean genotypes, with six replications. The substrate was a Red Eutrophic Oxisol with low P content. For application of the P treatments, it was applied simple superphosphate, consisting of two levels: restrictive and control, with the application of 45 and 90 kg∙ha–1 of P2O5, respectively. At 28 days, we observed the first symptoms of nutrient deficiency, with the decrease in the relative chlorophyll index in the restrictive level treatment. In addition, the treatments were effective in differentiating effects of both factors levels of P and genotypes for most traits evaluated relative to shoot, root and grain yield. It was possible to classify the genotypes in relation to use efficiency and responsiveness to P application, according to their average yield performances. Seven genotypes presented better performances for both P levels, being classified as Efficient and Responsive: G 2333, IAC Carioca Tybatã, IAPAR 81, IAC Imperador, IAC Formoso, BRS Esplendor and IPR Tangará; the first four genotypes were also classified as Efficient and Responsive under hydroponic conditions.<hr/>RESUMO O feijoeiro comum é uma das leguminosas mais importantes na América Latina, sendo, na maioria das vezes, cultivado em solos com pouca disponibilidade de fósforo (P). Desta forma, este trabalho teve como objetivo avaliar as respostas de 20 genótipos de feijoeiro frente à deficiência de P. O delineamento experimental utilizado foi inteiramente casualizado em esquema fatorial 2 × 20, sendo o primeiro fator constituído pelas doses de P e o segundo fator, por 20 genótipos de feijão, com seis repetições. Como substrato, utilizou-se um Latossolo Vermelho Eutrófico, com baixo teor de P. Para aplicação dos tratamentos com doses de P, utilizou-se superfostato simples, constando de duas doses: restritiva e controle, com a aplicação, respectivamente, de 45 e 90 kg∙ha–1 de P2O5. Aos 28 dias, foi possível observar os primeiros sintomas de deficiência do nutriente, com a diminuição do índice relativo de clorofila no tratamento com a dose restritiva. Além disso, foi possível verificar que os tratamentos foram efetivos para diferenciar tanto os efeitos de doses quanto os efeitos de genótipos para a maioria das variáveis avaliadas quanto à parte aérea, ao sistema radicular e aos componentes de produção. Foi possível classificar os genótipos quanto à eficiência de uso e responsividade à aplicação do P de acordo com seus desempenhos produtivos médios. Sete genótipos destacaram-se apresentando desempenhos superiores à média em ambas as doses de P, sendo estes classificados como Eficientes e Responsivos: G 2333, IAC Carioca Tybatã, IAPAR 81, IAC Imperador, IAC Formoso, BRS Esplendor e IPR Tangará, sendo que os quatro primeiros genótipos também foram classificados como Eficientes e Responsivos em condições de hidroponia. <![CDATA[Effect of two wild rootstocks of genus <em>Passiflora</em> L. on the content of antioxidants and fruit quality of yellow passion fruit]]> ABSTRACT The nutritional importance of the fruit of passionfruit has prompted studies to assess its composition and antioxidant content and to evaluate it as a functional food in fresh fruit and concentrated juice markets. Currently, the use of wild species as rootstock has been recommended mainly for their positive effects such as tolerance to disease attack and maintenance of fruit quality of grafted cultivars. The aim of this study was to determine the effect of wild species of Passiflora gibertii N.E. Br. and Passiflora mucronata Lam as rootstock on the content of antioxidants and fruit quality of Passiflora edulis f. flavicarpa. The experimental design was completely randomized with four treatments and 25 replications, with a total of 100 experimental units. As a control treatment, plants of P. edulis from seed and grafted on the same species were used. Significant correlations were observed among the contents of β-carotene, ascorbic acid, luminosity values, chroma and hue angle. For the combination P. edulis/P. gibertti, the contents of β-carotene and ascorbic acid were highly correlated with luminosity, chroma and hue angle of fruit juice. A similar behavior was observed for the combination P. edulis/P. mucronata Lam. The content of β-carotene in the fruit showed no statistical differences (p &lt; 0.05), indicating no significant rootstock effect on the variables evaluated. The results indicate a potential wild rootstock use for its positive effects on grafted plants while maintaining the commercial quality of the fruits of passionfruit crops. <![CDATA[Elevada densidade de semeadura aumenta a produtividade da soja? Respostas da radiação fotossinteticamente ativa]]> Resumo Estudos recentes têm abordado o uso da prática da elevada densidade de semeadura na cultura da soja. Entretanto, os resultados práticos dessa técnica são divergentes. Assim, pesquisas nesse campo são importantes para elucidar os efeitos diretos dessa prática de manejo, como, por exemplo, a interferência no uso da radiação fotossinteticamente ativa (RFA). Portanto, objetivou-se com este estudo avaliar a dinâmica da RFA em diferentes densidades de cultivo na cultura da soja. Para tanto, conduziu-se um experimento a campo com delineamento em blocos casualizados com os tratamentos distribuídos em arranjo fatorial 3 × 5: três cultivares de soja RR® (P98Y12, TMG 132 e M-Soy 9056) e cinco densidades de semeadura (20, 30, 40, 50 e 60 plantas∙m–2) com quatro repetições. Foram avaliados massa seca da parte aérea, radiação fotossinteticamente ativa no dossel inferior (RFA-I) e superior (RFA-S), intercepção da RFA, taxa de crescimento da cultura (TCC), taxa de crescimento relativo (TCR), taxa de assimilação líquida (TAL), eficiência de uso da radiação (EUR), coeficiente de extinção luminosa (k), índice de colheita de grãos (ICG), peso de 1.000 grãos e produtividade. Independentemente do cultivar, as densidades de 20 e 30 plantas∙m–2 proporcionaram os maiores valores de TAL, TCR, k, ICG e produtividade. Apenas o uso dos parâmetros EUR, TCC e RFA interceptada não fornece informações sólidas para predizer a eficiência do cultivo adensado na cultura da soja. As densidades de cultivo tradicionalmente utilizadas se sobrepõem às demais quanto à qualidade da RFA no dossel e produtividade da soja.<hr/>Abstract Recent studies have addressed the use of the high sowing density of soybean. However, the field results of this practice are still unclear. Thus, research on this area is important in order to explain the direct effects of this management practice, for example, interference in the use of photosynthetically active radiation (PAR). Therefore, this study aimed to evaluate the dynamics of PAR in different seeding densities in soybean. A field experiment was conducted in randomized blocks with treatments distributed in a 3 × 5 factorial arrangement: three varieties of RR® soybeans (P98Y12, TMG 132 and M-Soy 9056) and five seeding densities (20, 30, 40, 50 and 60 plants∙m–2) with four replications. The dry matter, photosynthetically active radiation in the lower canopy (PAR-L) and in the higher one (PAR-H), interception of PAR, crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), radiation use efficiency (RUE), light extinction coefficient (k), grain harvest index (GHI), 1,000 grains weight and productivity were evaluated. Regardless of the variety, the densities of 20 and 30 plants∙m–2 provided the highest values of NAR, RGR, k, GHI and productivity. The use of RUE, CGR and intercepted PAR does not provide accurate information to predict the efficiency of soybean density cultivation. Cultivation densities traditionally used overlap the others regarding the quality of PAR in the canopy and soybean productivity. <![CDATA[Damage caused by fungi and insects to stored peanut seeds before processing]]> Abstract The aim of this study was to gather data on the incidence of fungi associated with peanut seeds stored in their pods, before being processed by the State of São Paulo seed-producing companies, and the relation of the fungi to the seed damage caused by insects and to the quality of the stored seeds. Samples were taken from seed lots of cultivars IAC 886 and IAC 503 stored by these companies at the beginning and end of a six-month storage period. The peanut seeds were shelled and half of each sample was treated with fludioxonil + metalaxyl. Untreated and treated seeds were analyzed for moisture content, germination, vigor and health. The following insects were found to damage the peanut seeds: Cyrtomenus mirabilis (Perty) (Hemiptera: Cydnidae) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). Both species reduced seed quality. When present, fungi of the genera Aspergillus, Fusarium, Penicillium and Rhizopus infected seeds and seedlings during the germination process and were considered the main limiting factor for obtaining normal seedlings. Nevertheless, despite their presence, peanut seeds maintained their germination capacity and vigor after six months of storage in their pods. <![CDATA[Reação de progênies de café arábica derivadas do Icatu a <em>Meloidogyne paranaensis</em>]]> ABSTRACT The aim of this study was to evaluate the reaction of Arabica coffee progenies derived from Icatu to Meloidogyne paranaensis. The experiment was conducted under screenhouse conditions at Instituto Agronômico do Paraná (IAPAR) in Londrina, Paraná State, Brazil. Seedlings with three to four pairs of leaves were inoculated with 5,000 M. paranaensis eggs and second-stage juveniles (J2). Four F4 progenies of HN 87609 derived from Icatu H4782-7-925 were evaluated. C. arabica cv. Catuaí Vermelho IAC 81 and C. arabica cv. IPR 100 were susceptible and resistant checks, respectively. The experiment was conducted in a randomized blocks design with 14 replications of one plant per plot. Assessments were performed 120 days after inoculation. The number of eggs and second-stage juveniles (J2) per gram of roots (Nematodes∙g–1) and reproduction factor (RF) were evaluated. Host susceptibility index (HSI) was used to classify the resistance levels of coffees. In relation to Nematodes∙g–1, IAPAR 12232 and IAPAR 12231 progenies were not significantly different from the resistant check IPR 100. All F4 progenies of HN 87609 were classified as highly resistant by HSI and presented 100% of plants classified as highly resistant or resistant. Therefore, these progenies are homozygously resistant to Meloidogyne paranaensis.<hr/>RESUMO O objetivo do trabalho foi avaliar a reação ao nematoide Meloidogyne paranaensis em progênies de café arábica derivadas do Icatu. O experimento foi conduzido em telado, no Instituto Agronômico do Paraná (IAPAR), em Londrina, Paraná, Brasil. Mudas com três a quatro pares de folhas foram inoculadas com 5.000 ovos e juvenis de segundo estádio (J2) de Meloidogyne paranaensis. Foram avaliadas quatro progênies F4 de HN 87609 derivadas de ‘Icatu H4782-7-925’. Como padrões de suscetibilidade e resistência, foram utilizados, respectivamente, Coffea arabica cv. Catuaí Vermelho IAC 81 e C. arabica cv. IPR 100. O experimento foi instalado em blocos casualizados com 14 repetições e uma planta por parcela. As avaliações foram efetuadas 120 dias após a inoculação. Foram avaliados o número de ovos e J2 por gramas de raiz (Nematoides∙g–1) e o fator de reprodução (FR). Para classificar os níveis de resistência das progênies, foi utilizado o índice de suscetibilidade do hospedeiro (ISH). De acordo com Nematoides∙g–1, as progênies IAPAR 12232 e IAPAR 12231 não diferiram estatisticamente do padrão resistente ‘IPR 100’. Todas as progênies F4 de HN 87609 foram altamente resistentes pelo ISH e apresentaram 100% das plantas classificadas como altamente resistentes ou resistentes. Portanto, a resistência a M. paranaensis está condição homozigótica. <![CDATA[Alkaloids and phenolics biosynthesis increases mango resistance to infection by <em>Ceratocystis fimbriata</em>]]> ABSTRACT Mango wilt, caused by Ceratocystis fimbriata, is one of the most important diseases affecting mango yields in Brazil. Information regarding the biochemical mechanisms involved in mango resistance against C. fimbriata is absent in the literature. Thus, the present study determined and quantified alkaloids and phenolics in the stem tissue of mango plants from Palmer (susceptible) and Ubá (resistant) cultivars. Furthermore, it was examined the effect of these secondary metabolites against C. fimbriata growth in vitro. The high-performance liquid chromatography revealed that the concentration of two alkaloids (theobromine and 7-methylxanthine) and six phenolic compounds (caffeic acid, p-coumaric acid, gallic acid, protocatechuic acid, catechin and epicatechin) in the inoculated plants from cv. Ubá was higher in comparison with inoculated plants from cv. Palmer. The concentration of the secondary metabolites was higher in the non-inoculated plants from cv. Palmer than in the inoculated ones, while the opposite was observed for plants of cv. Ubá. Peaks in the concentrations of secondary metabolites in the inoculated plants from both cultivars occurred at 7 and 14 days after inoculation. The different concentrations (10 to 30 mg∙mL−1) of secondary metabolites added to the Petri dishes greatly inhibited C. fimbriata growth over time. These results suggest that secondary metabolites played an important role in the resistance of mango plants against C. fimbriata infection. <![CDATA[Silicon, acibenzolar-S-methyl and potassium phosphite in the control of brown spot in rice]]> ABSTRACT This study investigated the effects of silicon (Si), acibenzolar-S-methyl (ASM), and potassium phosphite (Phi) on the potentiation of rice resistance to infection by Bipolaris oryzae. The treatments included the soil amended with Si (1.25 g of calcium silicate per kg of soil), spraying of plants with ASM (500 mg∙L–1), Phi (5 mL∙L–1), and distilled water (control) 24 h before inoculation with B. oryzae. The treatments Si supply and the spraying of ASM and Phi were effective in reducing the area under brown spot progress curve and the number of lesions per cm2 of leaf. Polyphenoloxidases activity was higher for plants supplied with Si. On plants sprayed with ASM, the activities of polyphenoloxidases, phenylalanine ammonia-lyases, chitinases, and β-1,3-glucanases increased. The spraying of plants with Phi did not increase the activities of the studied defense enzymes. Taken together, the results of this study indicated that brown spot symptoms can be greatly reduced with the use of Si, ASM, and Phi. <![CDATA[Substratos de fibra de coco granulada e casca de arroz para a produção do morangueiro ‘Oso Grande’]]> RESUMO O morangueiro, cultivado em solo, torna-se suscetível a fungos nele presentes. Rotações de áreas de plantio são fundamentais para o manejo fitossanitário, realidade impraticável para alguns produtores brasileiros com áreas reduzidas para o cultivo. Essa problemática incentivou o uso de substratos, padrão técnico já bem estabelecido na Europa. O objetivo foi avaliar a resposta do morangueiro (‘Oso Grande’) em três tipos de substratos (fibra de coco granulada, casca de arroz pura e a mistura dos dois em iguais proporções), volumes (1,0; 1,5 e 2,0 L) e frequências de irrigação (duas, três e quatro vezes por dia). O experimento foi realizado em casa de vegetação, em Jundiaí (SP), no período de 2 de julho a 4 de outubro de 2010. Os dados foram submetidos à análise conjunta de experimentos, em esquema fatorial triplo (frequências de irrigação, tipos de substratos e volumes de substrato). O melhor resultado foi para a mistura de substratos, irrigada três vezes por dia, em 1,0 L do material, com produtividade média de 223 g por planta. A casca de arroz é ineficiente para o cultivo em vaso. Entretanto, na forma de misturas, esse substrato torna-se adequado ao cultivo, possibilitando melhores resultados quando comparado à fibra de coco granulada.<hr/>ABSTRACT The strawberry, when grown in soil, becomes susceptible to fungi present on it. Rotations of planted areas are essential to control disease, reality unworkable for some Brazilian farmers who have small areas for cultivation. This problem encouraged the use of substrates, a technical pattern already well-established in Europe. The objective was to assess the response of strawberry growth (‘Oso Grande’) on three substrates (granulated coconut fiber, pure rice husk and a mixture of both in equal proportions), volumes (1.0; 1.5 and 2.0 L) and irrigation frequencies (twice, three and four times a day). The experiment was carried out in a greenhouse in Jundiaí (SP), from July 2 to October 4, 2010. The data were submitted to the joint analysis of experiments, in a triple factorial scheme (irrigation frequencies, substrate types and substrate volumes). The best result obtained occurred for substrate mixture, with the irrigation frequency of three times a day, in 1.0 L of the material, with an average yield of 223 g per plant. Rice husk is ineffective for cultivation in pots. Nevertheless, in the form of mixtures, this substrate is suited for cultivation, allowing better results when compared to granulated coconut fiber. <![CDATA[Controlled atmosphere maintains native and cultivated yerba mate quality during shelf life after long-term storage]]> ABSTRACT Yerba mate shows social and economic importance for the Southern Latin American countries due to its easy production and large market range. However, there is a problem to harvest the yerba mate at the correct period and to store it until processing and marketing. Thus, the aim of this paper was to evaluate the interaction among the storage in controlled atmosphere, effect of cultivation form and shelf life period on yerba mate quality after long-term controlled atmosphere storage. The experiment was conducted in a factorial arrangement (3 controlled atmosphere conditions × 2 cultivation forms × 4 weeks of shelf life). Native yerba mate, stored under controlled atmosphere, showed higher chlorophyll concentration as compared to the cultivated one. Carotenoid concentration increased up to the third week of shelf life and thereafter remained constant, if the yerba mate was stored under ambient conditions. Oxygen partial pressure lowering allows long-term yerba mate storage, keeping its quality during four shelf life weeks at 20 °C. Controlled atmosphere is an efficient technique for yerba mate quality keeping during long-term storage and shelf life, allowing the harvest of the raw material at the correct period and the maintenance of its quality until processing and marketing. The cultivation form has a significant effect on the storage and shelf life potential of yerba mate stored under controlled atmosphere. <![CDATA[Storability of ‘Tupy’ and ‘Guarani’ blackberries in controlled atmosphere]]> ABSTRACT The aim of this work was to compare the storage potential of ‘Guarani’ and ‘Tupy’ blackberries in controlled atmosphere (CA) and thereafter to determinate the best CA storage conditions for ‘Tupy’ blackberries. Two experiments were carried out. In the first one, ‘Guarani’ and ‘Tupy’ blackberries were stored in CA condition (10 kPa O2 + 15 kPa CO2). We found that ‘Tupy’ blackberry has the best storage potential. Therefore, in the second experiment, several CA conditions were evaluated for ‘Tupy’ blackberries storage, as follows: [1] cold storage (CS): 20.9 kPa O2 + 0.04 kPa CO2; [2] CA with 10 kPa O2 + 15 kPa CO2; [3] CA with 5 kPa O2 + 15 kPa CO2; [4] CA with 10 kPa O2 + 10 kPa CO2. All treatments were stored at 1 °C and 98% (± 1) of relative humidity. The ‘Tupy’ blackberry, despite showing a significant decrease in ascorbic acid content, presented a higher storage potential than ‘Guarani’ blackberry, if stored at recommended CA condition for other cultivars. ‘Tupy’ blackberry stored at 5 kPa O2 + 15 kPa CO2 showed higher ascorbic acid content, soluble solids and titratable acidity as compared to the other storage conditions. In CA with 10 kPa O2 + 15 kPa CO2, the juice was lighter (high L), but differed significantly only from those fruit of CS. The best CA condition for ‘Tupy’ blackberries storage is 5 kPa O2 with 15 kPa CO2. <![CDATA[Modelo agrometeorológico-espectral para estimativa da produtividade de grãos de arroz irrigado no Rio Grande do Sul]]> RESUMO O objetivo deste trabalho foi elaborar e testar um modelo agrometeorológico-espectral para a estimativa da produtividade de grãos de arroz irrigado para o Estado do Rio Grande do Sul. Para as seis regiões orizícolas do Estado, foram utilizados dados de área cultivada e rendimento de grãos de arroz irrigado, dados meteorológicos e imagens do Índice de Vegetação por Diferença Normalizada (NDVI) do sensor Moderate Resolution Imaging Spectroradiometer (MODIS), de agosto a abril, para as safras de 2000/2001 até 2009/2010. A temperatura mínima do ar e o NDVI estão associados ao rendimento de grãos de arroz irrigado em diversos períodos do desenvolvimento da cultura. O modelo agrometeorológico-espectral para estimativa de produtividade de grãos, ajustado através da abordagem orientada pelas relações clima-planta, é adequado às estimativas em nível regional, podendo fornecer estas com cerca de um mês de antecedência ao final da colheita.<hr/>ABSTRACT The objective of this study was to estimate the irrigated rice grain yield through the adjustment of the agrometeorological-spectral model in the State of Rio Grande do Sul, Brazil. For the six rice-growing regions of the State, the data on irrigated rice grain yield and crop area, meteorological data and the Normalized Difference of Vegetation Index (NDVI) images of moderate resolution imaging spectroradiometer (MODIS) sensor were used from August to April, for the 2000/2001 to 2009/2010 crop seasons. The minimum air temperature and NDVI are associated to the irrigated rice grain yield in several crop development periods. The agrometeorological-spectral model to estimate irrigated rice grain yield, adjusted through the oriented approach by the climate-plant relationship, is adequate for the estimates at regional levels. This could predict the estimates one month before the end of the harvest.