Predicting developmental growth stages in soft red winter wheat (Triticum aestivum L.) (SRWW) could improve agronomic management in Kentucky. However, predicting SRWW development is complex due to vernalization requirement and photoperiod sensitivity differences of cultivars. The objectives of this study are to (1) determine ability of Kompetitive Allele Specific PCR (KASP) genotyping to predict phenotype; (2) determine the relative vernalization requirement (RVR) of 50 SRWW cultivars in a greenhouse (GH) assay; and (3) measure growing degree-days (GDD) required by cultivars to reach eight growth stages in a field assay. Fifty SRWW cultivars were characterized with 14 KASP markers for Vrn and Ppd loci. Additionally, cultivars were grown in a GH, vernalized outdoors for three, six, or nine weeks, and moved back into the GH where days to full flower were measured. Cultivars were also seeded into hill plots monthly from October to March at Princeton (2016; 2017) and Lexington, KY (2017) in three field trials. Cumulative GDD to emergence, green-up, pseudo-stem erection, jointing, flag leaf, beginning flower, full flower, and harvest maturity were measured. Field trials and supporting historical wheat development data suggest that prediction of SRWW growth and development is possible using a cumulative GDD scale in Kentucky.

Grain sorghum [Sorghum bicolor (L.) Moench] varieties fail to reach maturity in North Dakota’s short and cool growing season. The study objective was to evaluate seeding date and white grain sorghum genotypes. A randomized complete block design study was conducted at Carrington, Oakes, and Prosper, ND, in 2018 and 2019. Genotypes included two commercial hybrids and four open-pollinated genotypes. Reaching heading and anthesis, hybrids required more heat units (GDDs), compared with the open-pollinated genotypes. Highest grain yield was obtained from the first and second seeding dates. Earlier-maturing open-pollinated genotypes maintained yield across seeding dates, whereas yield was reduced at later dates for the longer maturity hybrids. Hybrids produced the highest number of kernels per panicle at the first seeding date with fewer seeds at each successive seeding date. Although the open-pollinated genotypes out-yielded the hybrids at later seeding dates, the risk of lodging is too great to recommend their commercialization.

Nineteen bermudagrass (Cynodon dactylon (L.) Pers.) cultivars were evaluated for field emergence, establishment rate, traffic tolerance, post-harvest seed coating, germination velocity, and total germination under varying temperature regimes. Two cultivars were evaluated for thermal modeling, day/night temperature fluctuations, day lengths, and effects of fluridone on speed and percentage of total germination. The effect of cultivar was highly significant for visible field germination, time to 100% cover, and traffic tolerance in both 2010 and 2011. Riviera was the slowest or equivalent to the slowest for visible germination. Casino Royale was the fastest or equivalent to the fastest for visible germination. Yukon was the slowest to reach 100% cover in both years, while Sovereign was the quickest for 2010. Riviera and Sovereign were equivalent for the quickest to cover in 2011. Riviera and Yukon ranked highest and lowest, respectfully, in tolerance to simulated athletic traffic. There were no significant effects (p>0.05) of post-harvest seed coatings. There were highly significant differences among cultivars in germination velocity and total germination when grown under 20-year average day/night temperatures representing data from Lexington, KY on 15 May to 1 August in 15 day intervals. Evaluations for day/night temperature regimes, day length regimes, and effects of fluridone on the germination speed and percentage were also completed on Riviera and Casino Royale. Day/night regimes of 35/20, 35/25, and 40/25 degrees Celsius were evaluated. Significant differences (p<0.05) were observed, 35/20oC producing the fastest and highest percentage of germination across both cultivars. Day length was evaluated for 8, 12, 14, and 16 hours with no significant differences (p<0.05) observed. Fluridone significantly (p<0.05) decreased the germination time and increased the percentage of total germination of Riviera while only significant differences (p<0.05) in germination time observed with Casino Royale.

No description available.

O presente trabalho tem por objetivo propor um modelo para estimação da produtividade de grãos de milho para o Estado de São Paulo com base nos valores mensais de temperatura, radiação solar e chuva, no intuito de disponibilizar ferramenta para o planejamento regional (identificação das épocas do ano e dos locais mais indicados para o cultivo de milho). O uso de modelos de crescimento e desenvolvimento vegetal possibilita uma economia de tempo, trabalho e quantidade de recursos para tomada de decisões referentes ao manejo no setor agrícola por possibilitar uma previsão do processo de interesse e/ou um melhor entendimento do sistema em estudo. O conhecimento da quantidade de energia solar disponível às plantas, bem como da capacidade de conversão da mesma em energia química metabólica, possibilita prever produtividade de grãos, no caso do milho, quanto à eficiência de conversão em biomassa, através de um modelo geral mecanístico, levando em consideração aspectos agrometeorológicos, fisiológicos, genéticos e edáficos. A assimilação de CO2 pode ser convertida em massa de carboidrato, produzida durante o processo de fotossíntese, em função do índice de área foliar, temperatura e radiação solar absorvida. Estimando-se os valores de radiação solar absorvida, fotoperíodo, índice de área foliar e duração do ciclo, considerando as correções quanto à respiração de manutenção e crescimento, bem como a variação temporal da área foliar, pode-se transformar esse valor em massa líquida de carboidrato total final produzida durante o ciclo. O balanço hídrico foi utilizado com a finalidade de estimar a deficiência hídrica durante o ciclo da cultura de milho, sendo adotado o método de Thornthwaite & Mather (1955), sendo a evapotranspiração de referência estimada pelo método de Thornthwaite (1948). A produtividade deplecionada de grãos de milho foi estimada a partir dos dados de produtividade potencial predita pelo modelo, considerando-se a depleção em função da evapotranspiração relativa (relação entre evapotranspiração real e evapotranspiração da cultura). A partir de dados climáticos obtidos de estações e postos meteorológicos localizados em diversas partes do estado de São Paulo, foram elaborados mapas de superfície no programa TNTmips, com a identificação, por município, das localidades com potencial para o desenvolvimento da cultura de milho. Através destes mapas, é possível identificar restrições quanto à deficiência hídrica, temperatura, radiação solar, produtividade potencial e produtividade de grãos de milho no estado de São Paulo. / The present work has the objective to suggest a model to estimate potential yield and corn yield for São Paulo state based on monthly values of temperature, solar radiation and rainfall, in order to dispose a tool for regional planning (identification of sites and timing during the year more indicated for maize cropping). The use of growing and development models allows savings in time, work and resources needed for making decisions regarding agricultural management, by enabling a preview of the process of interest and/or a better understanding of the system being studied. The knowledge of the available amount of solar energy to plants and the capability of those to convert it into metabolic chemical energy, allows to preview grain yield, in the case of corn, regarding to biomass converting efficiency, through a general mechanistic model, considering agro-meteorological, physiological, genetical and edaphological aspects. The carbon dioxide (CO2) assimilation can be converted into mass of carbohydrates produced during photosynthesis process, as a function of leaf area index, air temperature and absorbed solar radiation. By estimating the values of solar radiation, the photoperiod, the leaf area index, and the cycle length, and considering the corrections related to growing and maintenance respiration, as well as the temporal variation of leaf area, it is possible to transform those value into final net mass of total carbohydrate produced during the cycle. The hydric balance, as proposed by Thornthwaite & Mather (1955), was used with the objective to estimate the hydric deficit during maize cycle, being the reference evapotranspiration being estimated by Thornthwaite (1948). Corn yield was estimated up from potential yield predicted by the model, considering the depletion from the relative evapotranspiration (relation between real evapotranspiration and crop evapotranspiration). Starting from climatic data obtained from several meteorological station located at different sites in São Paulo State, Brazil, surface maps were elaborated using TNTmips software, with the identification, by county, of those sites with maize development potential. Through those maps it is possible to identify restriction regarding hydric deficit, temperature, solar radiation, potential yield, and corn yield in São Paulo State.

O presente trabalho tem por objetivo propor um modelo para estimação da produtividade de grãos de milho para o Estado de São Paulo com base nos valores mensais de temperatura, radiação solar e chuva, no intuito de disponibilizar ferramenta para o planejamento regional (identificação das épocas do ano e dos locais mais indicados para o cultivo de milho). O uso de modelos de crescimento e desenvolvimento vegetal possibilita uma economia de tempo, trabalho e quantidade de recursos para tomada de decisões referentes ao manejo no setor agrícola por possibilitar uma previsão do processo de interesse e/ou um melhor entendimento do sistema em estudo. O conhecimento da quantidade de energia solar disponível às plantas, bem como da capacidade de conversão da mesma em energia química metabólica, possibilita prever produtividade de grãos, no caso do milho, quanto à eficiência de conversão em biomassa, através de um modelo geral mecanístico, levando em consideração aspectos agrometeorológicos, fisiológicos, genéticos e edáficos. A assimilação de CO2 pode ser convertida em massa de carboidrato, produzida durante o processo de fotossíntese, em função do índice de área foliar, temperatura e radiação solar absorvida. Estimando-se os valores de radiação solar absorvida, fotoperíodo, índice de área foliar e duração do ciclo, considerando as correções quanto à respiração de manutenção e crescimento, bem como a variação temporal da área foliar, pode-se transformar esse valor em massa líquida de carboidrato total final produzida durante o ciclo. O balanço hídrico foi utilizado com a finalidade de estimar a deficiência hídrica durante o ciclo da cultura de milho, sendo adotado o método de Thornthwaite & Mather (1955), sendo a evapotranspiração de referência estimada pelo método de Thornthwaite (1948). A produtividade deplecionada de grãos de milho foi estimada a partir dos dados de produtividade potencial predita pelo modelo, considerando-se a depleção em função da evapotranspiração relativa (relação entre evapotranspiração real e evapotranspiração da cultura). A partir de dados climáticos obtidos de estações e postos meteorológicos localizados em diversas partes do estado de São Paulo, foram elaborados mapas de superfície no programa TNTmips, com a identificação, por município, das localidades com potencial para o desenvolvimento da cultura de milho. Através destes mapas, é possível identificar restrições quanto à deficiência hídrica, temperatura, radiação solar, produtividade potencial e produtividade de grãos de milho no estado de São Paulo. / The present work has the objective to suggest a model to estimate potential yield and corn yield for São Paulo state based on monthly values of temperature, solar radiation and rainfall, in order to dispose a tool for regional planning (identification of sites and timing during the year more indicated for maize cropping). The use of growing and development models allows savings in time, work and resources needed for making decisions regarding agricultural management, by enabling a preview of the process of interest and/or a better understanding of the system being studied. The knowledge of the available amount of solar energy to plants and the capability of those to convert it into metabolic chemical energy, allows to preview grain yield, in the case of corn, regarding to biomass converting efficiency, through a general mechanistic model, considering agro-meteorological, physiological, genetical and edaphological aspects. The carbon dioxide (CO2) assimilation can be converted into mass of carbohydrates produced during photosynthesis process, as a function of leaf area index, air temperature and absorbed solar radiation. By estimating the values of solar radiation, the photoperiod, the leaf area index, and the cycle length, and considering the corrections related to growing and maintenance respiration, as well as the temporal variation of leaf area, it is possible to transform those value into final net mass of total carbohydrate produced during the cycle. The hydric balance, as proposed by Thornthwaite & Mather (1955), was used with the objective to estimate the hydric deficit during maize cycle, being the reference evapotranspiration being estimated by Thornthwaite (1948). Corn yield was estimated up from potential yield predicted by the model, considering the depletion from the relative evapotranspiration (relation between real evapotranspiration and crop evapotranspiration). Starting from climatic data obtained from several meteorological station located at different sites in São Paulo State, Brazil, surface maps were elaborated using TNTmips software, with the identification, by county, of those sites with maize development potential. Through those maps it is possible to identify restriction regarding hydric deficit, temperature, solar radiation, potential yield, and corn yield in São Paulo State.