Efeitos de dose de nitrogênio, fósforo e potássio sobre os componentes da produção e a qualidade de bananas 'Prata Anã' no distrito agroindustrial de Jaíba

Com o objetivo de verificar os efeitos da adubação nitrogenada, fosfatada e potássica sobre os componentes da produção e a qualidade de bananas 'Prata Anã', no Distrito Agroindustrial de Jaíba, em Matias Cardoso-MG, foi conduzido um experimento com dez tratamentos constituídos pela combinação de doses (g/touceira) de N, P e K de acordo com uma matriz baconiana, sendo 1: 250-45-700, 2: 250-25-700, 3: 250-70-700, 4: 250-100-700, 5: 250-45-300, 6: 250-45-500, 7: 250-45-1000, 8: 150-45-700, 9: 400-45-700, 10: 600-45-700. O tratamento um é o de referência, correspondendo às doses adotadas pelos bananicultores da região. O delineamento foi de blocos ao acaso com quatro repetições. Avaliou-se a produção do primeiro ciclo. Os cachos foram colhidos, despencados e avaliados quanto ao número de pencas, número de frutos e massa do cacho, massa média das pencas e massa média, diâmetro e comprimentos total e comercial do fruto. Os resultados indicaram que as doses de nitrogênio ou fósforo utilizadas pelos produtores de banana do Distrito Agroindustrial de Jaíba podem ser reduzidas para 150 ou 25 g/touceira, respectivamente, sem prejuízo para a produção e qualidade dos frutos. Por outro lado, as doses de potássio até 1000 g/touceira, parceladas semanalmente, proporcionaram aumentos significativos na massa, comprimento total e comercial do fruto.

Use of a pre-sidedress soil nitrate test (PSNT) to determine nitrogen fertilizer requirements for irrigated corn

In the present study, a 2-year N rate response experiment was conducted in different fields to monitor NO3-N soil profiles, N accumulation by the crop and final crop performance, in order to assess if soil NO3-N at pre-sidedressing (Pre-Sidedress Soil Nitrate Test, PSNT) is a reliable indicator for soil N availability for corn in the irrigated area served by canal d’Urgell (Lleida, Spain), and if the test can be used to separate responsive fields from non-responsive fields to sidedress N fertilizer applications. Preliminary soil N availability (N sidedress fertilizer rate + PSNT) critical levels to identify fields that need supplementary N fertilizer applications were established at ca. 300 and 210 kg NO3-N·ha–1, for PSNTrooting–zone and PSNT0–30 cm, respectively (for a yield goal of 14 t grain·ha–1).

Effect of temperature and carpel size during pre-anthesis on potential grain weight in wheat

The effect of environmental conditions immediately before anthesis on potential grain weight was investigated in wheat at the experimental field of the Faculty of Agronomy (University of Buenos Aires, Argentina) during 1995 and 1996. Plants of two cultivars of wheat were grown in two environments (two contrasting sowing dates) to provide different background temperature conditions. In these environments, transparent boxes were installed covering the spikes in order to increase spike temperature for a short period (c. 6 days) immediately before anthesis, i.e. between ear emergence and anthesis. In both environments, transparent boxes increased mean temperatures by at least 3n8 mC. These increases were almost entirely due to the changes in maximum temperatures because minimum temperatures were little affected. Final grain weight was significantly reduced by higher temperature during the ear emergence–anthesis period. It is possible that this reduction could be mediated by the effect of the heat treatment on carpel weight at anthesis because a curvilinear association between final grain weight and carpel weight at anthesis was found. This curvilinear association may also indicate a threshold carpel weight for maximizing grain weight.

Almanach du Père Peinard pour... : farci de galbeuses histoires et de prédictions épatouflantes / réd. Émile Pouget

1894.