FOTOSSÍNTESE EM DIFERENTES GENÓTIPOS DE FEIJOEIRO

The objective of this study was to evaluate the photosynthesis rates (PR), stomatal conductance (EC), root and plant dry weight , leaf area, chlorophyll a and b, total chlorophyll, using different genotypes of common beans. A field experiment (FE) was conducted in Cristalina, GO, Brazil, and a green house experiment (GH) was conducted at University of Brasilia, Brazil between August and November of 2002. A portable gas analyzer using infrared method was used in the evaluation of PR and EC. Chlorophyll concentration was determined by 80% acetone extraction method and a spectrophotometer. Plant biomass was estimated by measure the plant dry weight . Leaf area was estimated using a foliar area measurer. Most of the evaluated paramenters indicated different values according to the the genotypes in field and green house. The chlorophyll concentration had no correlation with other parameters. The photosynthetic  rate had positive correlation (r = 0,627) with grain production at R7 plant stage. There were no correlations among other parameters. Plant stage R7 was the best date to evaluate the effect of photosynthesis in grain production. KEYWORDS: Chlorophyll, Dry weight, Leaf area, Photosynthetic rate, Stomata conductance, Yield.El objetivo del presente trabajo fue evaluar el efecto de tasa de fotosíntesis (TF), conductividad estomática (CE), materia seca total de raíz y parte aérea, área foliar y clorofila a, clorofila be clorofila total, sobre la productividad en genotipos de frijol. Se realizaron dos experimentos, uno en campo (CP), en el municipio de Cristalina - GO, y otro en casa de vegetación (CV), en la Estación Experimental de la Universidad de Brasília - DF, entre agosto y noviembre de 2002 ... de la TF y CE, se utilizó el analizador portátil de gas por infrarrojo. El contenido de clorofila fue determinado por el método de extracción acetona 80% y lectura en espectrofotómetro. La biomasa vegetal se determinó mediante el método de secado y pesaje. El área foliar se determinó utilizando el medidor de área foliar. Los genotipos presentaron valores diferenciados para la mayoría de los parámetros evaluados, tanto en campo como en casa de vegetación. No hubo correlación en la mayoría de las combinaciones que involucraron épocas de evaluación, lugar de experimento (campo y casa de vegetación) y genotipos evaluados. El contenido de clorofila no se correlacionó con ninguno de los parámetros analizados. La tasa de fotosíntesis en la fase R7 presentó correlación positiva (r = 0,627) con la producción de grano. Los demás factores no se correlacionaron. La fase R7 fue la mejor época para evaluar el efecto de la fotosíntesis en la producción de granos.PALABRAS CLAVE: Área foliar, Clorofila, Conductividad estomática, Materia seca, Productividad, Tasa de fotosíntesis. O objetivo do presente trabalho foi avaliar o efeito de taxa de fotossíntese (TF), condutância estomática (CE), matéria seca total de raiz e parte aérea, área foliar e clorofila a, clorofila b e clorofila total, sobre a produtividade em genótipos de feijoeiro. Foram realizados dois experimentos, um em campo (CP), no município de Cristalina – GO, e outro em casa de vegetação (CV), na Estação Experimental da Universidade de Brasília - DF, entre Agosto e Novembro de 2002... Na avaliação da TF e CE, utilizou-se o analisador portátil de gás por infravermelho. O teor de clorofila foi determinado pelo método de extração acetona 80% e leitura em espectrofotômetro. A biomassa vegetal foi determinada pelo método da secagem e pesagem. A área foliar foi determinada utilizando-se o medidor de área foliar. Os genótipos apresentaram valores diferenciados para a maioria dos parâmetros avaliados, tanto em campo como em casa de vegetação. Não houve correlação na maioria das combinações que envolveram épocas de avaliação, local de experimento (campo e casa de vegetação) e genótipos avaliados. O teor de clorofila não se correlacionou com qualquer dos parâmetros analisados. A taxa de fotossíntese na fase R7 apresentou correlação positiva (r = 0,627) com a produção de grão. Os demais fatores não se correlacionaram. A fase R7 foi a melhor época para avaliar o efeito da fotossíntese na produção de grãos. PALAVRAS-CHAVE: Área foliar, Clorofila, Condutância estomática, Matéria seca, Produtividade, Taxa de fotossíntese

Adaptability and stability of irrigated wheat genotypes in the Cerrado of Central Brazil

O objetivo deste trabalho foi estimar a adaptabilidade e estabilidade de genótipos de trigo irrigado, nas condições do Cerrado do Brasil Central. O rendimento de grãos de cinco cultivares e nove linhagens de trigo irrigado foram aferidos no ensaio de valor de cultivo e uso. Os ensaios foram conduzidos nos anos de 2005 e 2006, em seis locais em Minas Gerais, três em Goiás e um no Distrito Federal. Os dados de rendimento de grãos foram submetidos à análise de variância individual e à análise de variância conjunta, para a estimativa dos parâmetros de adaptabilidade e estabilidade. Verificaram-se diferenças significativas, entre os genótipos, em 14 dos 16 ambientes avaliados. Nenhum dos genótipos avaliados apresentou o comportamento ideal preconizado pelo método de Cruz e colaboradores. Destacaram-se a cultivar BRS 264 e a linhagem CPAC 02167, pela superioridade em todas as condições do Cerrado do Brasil Central (adaptabilidade geral). Entre os demais genótipos avaliados, destacaram-se as cultivares BRS 207 e EMBRAPA 22, responsivas à melhoria das condições ambientais, e as cultivares BRS 254 e EMBRAPA 42, pela adaptabilidade específica a ambientes desfavoráveis ao cultivo de trigo irrigado.The aim of this work was to estimate the adaptability and stability of irrigated wheat genotypes under conditions of Central Brazil savannah area. Grain yield of five cultivars and nine lines of irrigated wheat was measured in assays of cultivation value and use. The assays were conducted during the years 2005 and 2006, in six locations in Minas Gerais State, three in Goiás State and one in Federal District. The data of grain yield were submitted to individual and joint ANOVA, in order to estimate the adaptability and stability parameters. Significant differences were detected between genotypes in 14 of the 16 locations evaluated. None of the evaluated genotypes have presented the behavior predicted by the method of Cruz and collaborators. Cultivar BRS 264 and the CPAC 02167 lineage were superior in all the tested conditions in the Central Brazil savannah (general adaptability). Among the other evaluated genotypes, it can be highlighted the responsiveness of the cultivars BRS 207 and EMBRAPA 22 to the improvement of environmental conditions, and the specific fitness of BRS 254 and EMBRAPA 42 cultivars to environments unfavorable to irrigated wheat

Nutrient accumulation in cover crops under contrasting water regimes in the Brazilian cerrado

Brazilian Cerrado has a dry period, and the inclusion of new species for diversification in the production system needs to be drought-tolerant. This work aimed to evaluate biomass and nutrient accumulation in species with potential as cover crops and grain crops under different water levels. Irrigation treatments were obtained through an irrigation bar with sprinklers with increasing water flows to create a continuous gradient. The experimental design randomized complete blocks in split plots with four replications. The main plots were composed of four water regimes (167 mm, 268 mm, 381 mm and 432 mm), and the subplots were formed by the following cover crops: Amaranthus cruenthus, Chenopodium quinoa and Pennisetum glaucum, the latter already used for this purpose. Amaranthus cruenthus and P. glaucum recorded the highest dry biomass (10.16 and 9.75 Mg ha−1, respectively). Dry biomass production and the cellulose contents decreased with the reduction of water availability for all species. A. cruenthus was the species that most accumulated P (37.42 kg ha−1), K (416.92 kg ha−1), Mg (30.88 kg ha−1), S (43.53 kg ha−1), Fe (2.22 kg ha−1), B (0.124 kg ha−1) and Zn (0.240 kg ha−1 ). Amaranthus cruenthus produced the highest yield. Under high and low water availability conditions, A. cruenthus presents potential as a cover crop and grain cash crop, in addition to accumulating more nutrients; P. glaucum has potential as a cover crop and C. quinoa only for grain production

Alterações fisiológicas de soja cultivada com remineralizador de solo no Cerrado sob regimes hídricos variáveis

The objective of this work was to evaluate the influence of the soil remineralizer fine-graded mica schist (FMS) on soybean (Glycine max) physiology, yield, and grain quality under different water regimes (WRs) in the Brazilian Cerrado. The experiment was conducted under field conditions for two years, using four WRs and three treatments: mica schist, conventional fertilization, and control. In 2017 and 2018, the following WRs were evaluated: WR1, WR2, WR3, and WR4, corresponding to a mean value of 100, 65, 44, and 28% of crop evapotranspiration replacement, respectively. Photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, effective quantum yield of photosystem II (PSII) (Fv’/Fm’), quantum yield (PSII) (ᶲFSII), and electron transport rate reduced as a function of the advanced phenological stage of soybean and the reduction in WR. Grain quality was only affected by the WR. The mica schist was statistically similar to conventional fertilization and the control in 2017 and 2018. Yield decreased due to the anticipation of soybean phenological age and WR, but there were no differences between the three treatments in 2017 and 2018. The reduction in soybean yield is attributed to stomatal closure, loss of photoprotective capacity, and damage to the photosynthetic machinery caused by drought.O objetivo deste trabalho foi avaliar a influência do remineralizador de solo finos de mica xisto (FMS) na fisiologia, na produtividade e na qualidade de grãos de soja (Glycine max) em diferentes regimes hídricos (RHs), no Cerrado brasileiro. O experimento foi conduzido em condições de campo durante dois anos, tendo-se utilizado quatro RHs e três tratamentos: mica xisto, adubação convencional e controle. Em 2017 e 2018, foram avaliados os seguintes RHs: RH1, RH2, RH3 e RH4, que correspondiam ao valor médio de 100, 65, 44 e 28% da reposição da evapotranspiração da cultura, respectivamente. A fotossíntese, a condutância estomática, a transpiração, a concentração interna de CO2, o rendimento quântico efetivo do fotossistema II (FSII) (Fv’/Fm’), o rendimento quântico (FSII) (ᶲFSII) e a taxa de transporte de elétrons reduziram em função do avanço da fase fenológica da soja e da redução do RH. A qualidade dos grãos foi afetada apenas pelo RH. O mica xisto foi estatisticamente semelhante à adubação convencional e ao controle em 2017 e 2018. A produtividade reduziu devido à antecipação da idade fenológica da soja e do RH, mas não houve diferenças entre os três tratamentos em 2017 e 2018. A redução da produtividade da soja é atribuída ao fechamento estomático, à perda da capacidade fotoprotetora e aos danos ao maquinário fotossintético causados pela seca

Physiological changes of Arabica coffee under different intensities and durations of water stress in the Brazilian cerrado

Coffee farmers have faced problems due to drought periods, with irrigation being necessary. In this sense, this study aimed to evaluate the responses to different levels and durations of water deficit in arabica coffee genotypes in the Cerrado region. The experiment consisted of three Coffea arabica genotypes and five water regimes: full irrigation (FI 100 and FI 50—full irrigation with 100% and 50% replacement of evapotranspiration, respectively), water deficit (WD 100 and WD 50—water deficit from June to September, with 100% and 50% replacement of evapotranspiration, respectively) and rainfed (without irrigation). The variables evaluated were gas exchange, relative water content (RWC) and productivity. The results showed that during stress, plants under the FI water regime showed higher gas exchange and RWC, differently from what occurred in the WD and rainfed treatments; however, after irrigation, coffee plants under WDs regained their photosynthetic potential. Rainfed and WD 50 plants had more than 50% reduction in RWC compared to FIs. The Iapar 59 cultivar was the most productive genotype and the E237 the lowest. Most importantly, under rainfed conditions, the plants showed lower physiological and productive potential, indicating the importance of irrigation in Coffea arabica in the Brazilian Cerrado

Host specificity among Bradyrhizobium japonicum strains and soybean cultivars with late maturation cycle

Foi desenvolvido um experimento em casa de vegetação, utilizando-se um LVE sob vegetação de cerrado, com o objetivo de estudar a especificidade hospedeira entre estir-pes de Bradyrhizobium japonicum e cultivares de soja recomendadas para o estado de Goiás. As cultivares utilizadas foram: Doko, Cristalina, EMGOPA-301, EMGOPA-303 e IAC-8. Os tratamentos de inoculação foram: sem inoculação, CB 1809,R54a, 965,29W, SEMIA 587 e mistura das estirpes. Em coleta feita no enchimento de grãos, observou-se que não houve efeito das cultivares e sim das estirpes inoculadas nos vários parâmetros, com exceção da per-centagem de N na parte aérea. As estirpes CB 1809 e B54a foram as mais eficientes. A culti-var Cristalina sobressaiu-se em relação à Doko, IAC-8 e EMGOPA-301. Não se observaram problemas de especificidade hospedeira entre as estirpes e as cultivares testadas.In a greenhouse experiment, the host specificity among strains of Bradyrhizobium japonicum and the soybean cultivars Doko, Cristalina, EMGOPA-301, EMGOPA-303 and IAC-8, recommended for the state of Goiás, Brazil, was studied. The inoculation treatments were: no inoculation, CB 1809, R54a, 965, 29W, SEMIA 587, and the mixture of those strains. A dark-red latosol under cerrado vegetation was used. Plants were collected at the filling pods stage and, except for N contents in the shoots, there were no differences among cultivars in the various parameters. Effects were observed from inoculated strains, with great nodulation generally being associated with lower shoot N content. The most effective strains were CB1809 and R54a. As related to N shoot content, Cristalina performed best. There was no host specificity among B. japonicum strains and soybean cultivars

Biometric responses of third ratoon sugarcane varieties under variable water regime

Water deficit is one of the main factors to limit sugar cane production. This paper’s goal is to characterize biometrically varieties of sugarcane under different water regimes. The experiment was performed using randomized design with three repetitions in parcels subdivided in time, in which three varieties: RB855156, RB835486 e RB867515 (plots), with absence and presence of irrigation (irrigated and rainfed - subplots) to which the plants were subjected, and data collection in six observations in time (50, 100, 150, 200, 250 and 300 days after cutting - DAC), were the subsubplots. The following biometrics were assessed: mean stem diameter (MSD), mean tiller height (MTH), number of green and completely open leaves (NoFOGL), length and width of +3 leaf (C+3 and L+3, respectively), leaf area index (LAI), leaf area (LA) and productivity. The data were subjected to variance analysis and regression at p<0.05. The variety RB867515 was the one that displayed higher MSD, MTH, C+3 and L+3 biometric values, both in irrigated cultivation and rainfed; it was observed that there was a decrease in NoFOGL values per tiller when the varieties were grown in rainfed conditions; the RB867515 variety had higher productivity, not differentiating to the RB855156, and proved better suited to water stress during the beginning of cultivation cycle