Hyperspectral crop reflectance data are useful for several remote sensing applications in agriculture, but there is still a need for studies to define optimal wavebands to estimate crop biophysical parameters. The objective of this work is to analyze the use of narrow and broad band vegetation indices (VI) derived from hyperspectral field reflectance measurements to estimate wheat (Triticum aestivum L.) grain yield and plant height. A field study was conducted during the winter growing season of 2003 in Campinas, São Paulo State, Brazil. Field canopy reflectance measurements were acquired at six wheat growth stages over 80 plots with four wheat cultivars (IAC-362, IAC-364, IAC-370, and IAC-373), five levels of nitrogen fertilizer (0, 30, 60, 90, and 120 kg of N ha-1) and four replicates. The following VI were analyzed: a) hyperspectral or narrow-band VI (1. optimum multiple narrow-band reflectance, OMNBR; 2. narrow-band normalized difference vegetation index, NB_NDVI; 3. first- and second-order derivative of reflectance; and 4. four derivative green vegetation index); and b) broad band VI (simple ratio, SR; normalized difference vegetation index, NDVI; and soil-adjusted vegetation index, SAVI). Hyperspectral indices provided an overall better estimate of biophysical variables when compared to broad band VI. The OMNBR with four bands presented the highest R² values to estimate both grain yield (R² = 0.74; Booting and Heading stages) and plant height (R² = 0.68; Heading stage). Best results to estimate biophysical variables were observed for spectral measurements acquired between Tillering II and Heading stages.
RESUMOFoi avaliada a resposta de três cultivares de arroz irrigado por inundação a diferentes doses de nitrogênio, mediante experimentos realizados em Mococa, SP, em 2000 e em 2001/2002. Nas parcelas foram aplicadas quatro doses de N (0, 90, 180 e 270 kg ha -1 ) e nas subparcelas foram transplantadas mudas das cultivares de arroz IAC 101, IAC 103 e EPAGRI 109. O nitrogênio, tendo como fonte a uréia, foi aplicado, no transplantio das mudas, aos 20 e 40 dias após. Os componentes de produção não responderam à aplicação do nitrogênio, porém as cultivares diferiram significativamente entre si, tendo se observado na 'IAC 103' maior valor para o índice de fertilidade da panícula e o número de panículas por unidade de área. O número de panículas por unidade de área foi o componente de produção que melhor se correlacionou com a produção de grãos. Verificaram-se nas cultivares respostas quadráticas à aplicação de nitrogênio para o rendimento de grãos em casca e inteiros. A 'IAC 103' respondeu a doses maiores de N e maximizou o retorno econômico (218 kg ha -1 de N, com rendimento de 6790 kg ha -1 de grãos em casca). As doses para maior retorno das demais cultivares foram 161 (EPAGRI 109) e 179 kg ha -1 de N (IAC 101).Palavras-chave: Oryza sativa L., produção de grãos, rendimento do benefício, nitrogênio. ABSTRACT RESPONSE OF RICE CULTIVARS UNDER WATER LOGGED CONDITIONS TO NITROGEN RATESThe objective of this study was to evaluate the response of three rice cultivars to N fertilizers under irrigated conditions. Two field experiments were carried out in Mococa, SP, in 2000/01 and 2001/02. Rates of N (0, 90, 180, and 270 kg ha -1 ) were applied in the main plots and seedlings of three rice cultivars (IAC 101, IAC 103, and EPAGRI 109) were transplanted into the subplots. Nitrogen, as urea, was split in three applications: at transplantation, 20 and 40 days later. Except for the number of spiklets per panicle, yield components did not respond to N rates, although they varied for the different plant genotypes. IAC 103 presented the higher value for panicle fertility index and number of panicles per area, and the lower plant height, compared to IAC 101 and EPAGRI 109. Number of plants per area was the yield component most closely related with grain yield. Responses to N varied with the genotype. The highest rate of N to maximize economic return (218 kg/ha N and 6790 kg/ha grain yield) was observed for IAC 103. The corresponding rates for the other genotypes were 161 (EPAGRI 109) and 179 kg/ha N (IAC 101). These rates are higher than those currently recommended for waterlogged rice in Brazil.
Palavras-chave:Triticum aestivum L., linhagens diaplóides, características agronômicas, resistência às doenças, tolerância ao alumínio. ABSTRACT PERFORMANCE OF WHEAT DIHAPLOID LINES AT TWO LOCATIONS OF THE STATE OF SÃO PAULO, BRAZILTwenty wheat genotypes (18 dihaploid lines and the IAC-24 and IAC-289 cultivars) were evaluated in experiments carried out under dryland and acid soil conditions in Capão Bonito , and under sprinkler irrigation and acid soil conditions with lime application in Tatuí (1997Tatuí ( -2000. Grain yield, yieldBragantia, Campinas, v.62, n.2, p.217-226, 2003 218 components, agronomic characteristics and disease resistance were analyzed. In addition, the genotypes were evaluated for their tolerance to Al toxicity, in nutrient solutions, at laboratory conditions. The dihaploid lines 10 and 11 and the cultivar IAC-24, in Capão Bonito, and the cultivar IAC-24 and the dihaploid line 19, in Tatuí, were superior for grain yield. The dihaploid line 5 presented lodging resistance, the line 20 showed short stature and early plants to mature, and the cultivar IAC-289 exhibited higher number of spikelets per spike and heavier grains. All evaluated genotypes were susceptible to leaf spot. In relation to leaf rust, all lines were resistant, except the line 20 which was moderately resistant. The cultivar IAC-24 and all evaluated dihaploid lines were tolerant to aluminum toxicity. The higher grain yield genotypes, under dryland and acid soil conditions, were associated to tall plants, with long spikes, with high number of grains per spike and per spikelet and with tolerance to aluminum. Under sprinkler irrigation and acid soil conditions with lime application the most productive genotypes were associated to tall plants (semidwarf type) with heavy grains, and presenting no correlation with tolerance to aluminum.
Primary root growth is very important for wheat (Triticum aestivum L.) crop in upland conditions in the State of São Paulo. Fourteen wheat genotypes (mutant lines and cultivars) were evaluated for primary root growth during 7 and 15 days of development in complete and aerated nutrient solutions, in the laboratory. In the first experiment, solutions with three pH values (4.0, 5.0 and 6.0) at constant temperature (24 ± 1°C), and in the second experiment, solutions with the same pH (4.0) but with three temperatures (18°C ± 1°C, 24°C ± 1°C and 30°C ± 1°C) were used. High genetic variability was observed among the evaluated genotypes in relation to primary root growth in the first stages of development in nutrient solutions independent of pH, temperature and growth period. Genotypes 6 (BH-1146) and 13 (IAC-17), tolerant to Al 3+ showed genetic potential for root growth in the first stages of development (7 and 15 days), regardless of nutrient solution temperature and pH. Genotypes 14 (IAC-24 M), 15 (IAC-24), 17 (MON"S" / ALD "S") × IAC-24 M 2 , 18 (MON"S" / ALD "S") × IAC-24 M 3 and 24 (KAUZ"S" / IAC-24 M 3 ), tolerant to Al 3+ , showed reduced root growth under the same conditions.
The aim of this study was to evaluate the effect of water stress on the germination of Coffea arabica seeds and the growth and development of plants from these seeds. Seeds of the cultivars Bourbon Vermelho, Mundo Novo, and BA-10 were placed to germinate in the dark at 30 ºC in the presence and absence of 100 g/L of polyethylene glycol 6000. The water stress applied delayed the beginning of seed germination by seven days in relation to seeds of the control, which had achieved responses of up to 50%, but there were no differences between the treatments at the end of the experiment. Furthermore, the length of the primary root in seeds germinated under water stress was less than in the control treatment, especially for the cultivar Mundo Novo. Plants of the cultivars Bourbon Vermelho and Mundo Novo developed from seeds previously germinated under water stress exhibited reduced height and fewer leaf pairs than those from the control, whereas ‘BA-10’ responded in a similar way in both treatments. Thus, the cultivars Bourbon Vermelho and Mundo Novo were more sensitive to the water stress applied in the germination phase than ‘BA-10’.
O emprego da técnica de indução de mutação associada à hibridação tem contribuído para a obtenção de novos genótipos de trigo com características agronômicas desejáveis. Avaliaram-se 18 linhagens de trigo, sendo dez oriundas de seleção de plantas do híbrido Kauz "S"x IAC-24 que tiveram as sementes, em geração F2, irradiadas (I) com raios gama e oito não irradiadas (NI), além das cultivares IAC-24 e IAC-289, em seis experimentos instalados no período 1997-99. Foram analisadas a produção de grãos, a resistência a doenças e outras características agronômicas. Em condições de laboratório, estudou-se a tolerância ao alumínio em soluções nutritivas, utilizando-se as cultivares BH-1146 (tolerante) e Anahuac (sensível), como controles. A linhagem L18-I destacou-se quanto à produção de grãos em condição de irrigação por aspersão e solo corrigido, nos três anos considerados. Em solo ácido e condição de sequeiro, L20-I, tolerante à toxicidade de Al3+, em soluções nutritivas, destacou-se quanto à produção de grãos, diferindo somente da IAC-289, a mais sensível à toxicidade de Al3+. IAC-289 e L9-NI destacaram-se na condição de sequeiro e solo corrigido, diferindo somente das linhagens L3-NI e L11-I. Na linhagem L11-I, observou-se porte mais baixo em todos os experimentos associado à resistência ao acamamento e à tolerância à toxicidade de Al3+. Todos os genótipos foram suscetíveis ao agente causal da mancha-da-folha. L9-NI tem potencial como fonte de genes em programas de melhoramento genético dada sua resistência à ferrugem-da-folha. Com exceção de Anahuac, IAC-289 e da L3-NI, todos os genótipos foram tolerantes à presença de 10 mg L-1 de Al3+ em soluções nutritivas.
de Al 3+ , quando avaliados em soluções nutritivas. Os resultados reforçam a possibilidade de selecionar os genótipos tolerantes ao alumínio, em condição de laboratório, antes que sejam avaliados em campo, em solo ácido, tornando o processo de obtenção de linhagens tolerantes mais eficiente.Palavras-chave: trigo, tolerância ao alumínio, produção de grãos, altura das plantas, linhagens diaplóides.
Foram avaliados dezesseis genótipos de arroz quanto ao seu nível de resistência parcial à brusone (Pyricularia grisea). A reação dos genótipos à doença foi avaliada durante dois anos, em condições de cultivo de terras altas, no município de Capão Bonito, SP. A severidade da doença nas folhas e panículas foi determinada periodicamente, e os dados foram utilizados para traçar a curva de progresso da doença e cálculo da área sob a curva de progresso da doença para cada genótipo (ASCPD). Os resultados evidenciaram que, considerando os dois anos de avaliação, menores valores de ASCPD foram apresentados nas folhas pelas linhagens IAC 1711, IAC 1774 e IAC 1781 e pelas cultivares BRS Bonança e BRS Liderança; nas panículas, pelas linhagens IAC 1738, IAC 1774 e IAC 1781 e pelas cultivares BRS Bonança, BRS Liderança e Carisma.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.