Cultivar de trigo IAC-24: rendimento de grãos e caracteres agronômicos em três faixas de umidade do solo Wheat cultivar IAC-24: grain yield and agronomic characters under three moisture levels

Num experimento conduzido em casa de vegetação, no Instituto Agronômico de Campinas, SP, em 1985, para estudar o comportamento do cultivar de trigo IAC-24 em três faixas de umidade (0,01-0,03; 0,03-0,50 e 0,50-1,50 MPa), empregaram-se vasos contendo latossolo roxo eutrófico e determinaram-se os seguintes caracteres agronômicos: comprimento da espiga, número de espigas por vaso e por planta, número total de espiguetas e espiguetas desenvolvidas por espiga, número de grãos por espigueta e por espiga e rendimento de grãos. Com o aumento da água disponível no solo, houve acréscimo significativo em todos os caracteres estudados, exceto para grãos por espigueta. Para as condições deste experimento e para os caracteres agronômicos estudados, a faixa de umidade crítica foi de 0,03-0,50 MPa. Desse modo, à medida que a água disponível desceu abaixo dessa faixa, ocorreu um decréscimo acentuado no rendimento de grãos e nos componentes de produção. Na comparação de uso das faixas de umidade do solo de 0,03-0,50 e 0,01-0,03 MPa, houve acréscimos de 39% no rendimento de grãos. Assim, a escolha da faixa de umidade a ser utilizada é de grande importância na produção de grãos e na economicidade da cultura.<br>An experiment with the objective to study the behaviour of the wheat cultivar IAC-24 under three moisture levels (0.01-0.03; 0.03-0.50 and 0.50-1.50 MPa), using pots with soil (Latossolo Roxo eutrófico) was carried out under green-house conditions at Instituto Agronômico, Campinas, State of São Paulo, Brazil, during 1985. It was measured spike lenght, number of spikes per pot and per plant, total number of spikelets per spike, number of grains per spikelet and per spike and grain yield as affected by the three soil moisture levels. All characters increased significantly as the water availability in the soil increased from 0.50-1.50 to 0.01-0.03 MPa. In the experiment the critical moisture level was 0.50 to 0.03 MPa; so as the water potential decreased below this level there was a decrease in grain yield and in the agronomic characteristics. Changing the moisture level of the soil from 0.03-0.50 to 0.01-0.03 MPa, there was a significant increase in the grain yield. The moisture level showed to be very important in studies where grain yield and economic value of the crop are involved

The productivity and response to inorganic fertilizers of species- rich wetland hay meadows on the Somerset Moors: nitrogen response under hay cutting and aftermath grazing

The productivity and response to fertilizer nitrogen (N) was measured in herb-rich wetland hay meadows within a Site of Special Scientific Interest (SSSI) in Somerset, UK. Output from hay cut after 1 July each year and from beef production at aftermath grazing was measured over a total of 4 years. Total utilized metabolizable energy (UME) output averaged from 40.6 GJ ha-1 year-1 without fertilizers to 61.7 GJ ha-1 at 200 kg N ha-1 (N-200), the highest rate used, with about two-thirds of this output from hay. N response was markedly curvilinear above about 50 kg N ha-1, but data from a concurrent experiment suggested that the comparatively low replacement rates of P and K applied were limiting at higher N rates. When hay cutting was delayed until early August in a wet year, yield response to N was lost because fertilized swards had passed a peak in yield several weeks before harvest. Compared with other published data, the results suggest that output and response to N is not constrained by the diversity of the flora or the damp conditions. The data will help to estimate the financial implications for farmers of restricted or zero fertilizer use within SSSIs and the wider Environmentally Sensitive Areas

Psoriatic arthritis screening tools: study design and methodologic challenges - reply from authors

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