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O cultivo de plantas oleaginosas tem aumentando extraordinariamente um pouco por todo o mundo. O presente trabalho teve por objetivo avaliar o efeito de diferentes aspetos culturais no comportamento da colza, girassol e soja em ensaios de campo. Os ensaios decorreram de setembro de 2015 a outubro de 2016 em Bragança (Portugal).
No ensaio da colza avaliou-se a resposta da cultura em três datas de sementeiras (25/09/2015, 16/10/2015 e 14/11/2015) e quatro modalidades de fertilização azotadas (fundo+cobertura: 25+125 kg N ha-1; 25+75 kg N ha-1; 25+25 kg N ha-1 e testemunha, sem aplicação de azoto). O ensaio foi conduzido em regime de sequeiro. No ensaio de girassol avaliaram-se alguns parâmetros morfológicos e a produtividade de seis variedades híbridas, cinco das quais recomendadas para o território português (Kiara, P63HH79, Oleko, Fortini e Mooelli) e uma para o território angolano (Chitra), quando cultivadas em duas densidades 40 000 (D4) e 60 000 (D6) plantas/ha também em regime de sequeiro. No ensaio da soja avaliou-se a produção de biomassa de uma variedade recomendada para o território angolano (Tabarana), quando cultivada em quatro densidades (133333, 200000, 250000 e 333333 plantas/ha) em regime de regadio.
Na colza, as diferentes datas de sementeiras revelaram diferenças significativas na produção de biomassa e no azoto exportado avaliados em três colheitas na fase vegetativa. A adubação azotada efetuada em fundo (antes da sementeira) não originou diferenças significativas na produção de biomassa e azoto exportado na primeira e na segunda colheita efetuadas na fase vegetativa antes da adubação de cobertura. Na terceira colheita efetuada após a adubação de cobertura, já foram registadas diferenças significativas entre os tratamentos fertilizantes. Na colheita, as diferentes datas de sementeiras revelaram diferenças significativas na produção de biomassa (na palha e no grão) e no azoto exportado. Quanto mais precoce a sementeira maior foi a produção e o azoto exportado. A adubação azotada também originou diferenças significativas entre tratamentos, tendo a produção aumentado até à dose de 100 kg N ha-1. A produção de grão atingiu 6000 kg ha-1 na modalidade mais produtiva. Os resultados mostraram de forma inequívoca grandes vantagens na sementeira precoce, devendo, se possível, ser efetuada ainda em setembro nesta região. A planta respondeu também a doses moderadas de azoto.
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No girassol, os diferentes híbridos revelaram características morfológicas distintas relativamente à altura, diâmetro do caule e diâmetro do capítulo. Estes parâmetros variaram também de forma significativa em função da densidade de plantação. As plantas cultivadas na densidade D4 apresentaram-se mais vigorosas, sendo significativamente mais altas, com maior diâmetro do caule e do capítulo e maior produção de grão por planta. Na densidade D4 a produção por unidade de área tendeu a ser superior relativamente a D6. Foi estabelecida uma relação linear significativa nos diferentes parâmetros de vigor entre si e entre estes e a produção de grão por planta. De notar que entre o diâmetro do caule e a produção de grão por planta foi estabelecida uma relação linear significativa com R2=0,79. A variedade mais produtiva foi a Kiara, com 2886 kg/ha.
Na soja as diferentes densidades de sementeiras não originaram diferenças significativas na produção de biomassa, concentração de azoto na planta e azoto exportado, embora estes parâmetros tenham aumentado de forma consistente com a densidade de sementeira, sugerindo o resultado que será possível obter melhores produções com a densidade mais elevadas (33,3 plantas m-2). Contudo, as plantas não terminaram o ciclo, não sendo possível registar a produção de grão. Nesta região o cultivo de soja terá de estar baseado em variedades de ciclo mais curto.
The cultivation of oil crops has increased extraordinarily across the world. The present work reports results of field trials conducted with three important oilseed crops, namely rapeseed, sunflower and soybean. The field trials were carried out from September 2015 to October 2016 in Bragança (Portugal). In the rapeseed trial it was assessed the crop response to three sowing dates (09/25/2015, 10/16/2015 and 11/14/2015) and four nitrogen fertilizer rates (preplant + top-dress: 25 + 125 kg ha-1; 25 + 75 kg ha-1; 25 + 25 kg ha-1 and control, without nitrogen application). The experiment was conducted under rainfed conditions. In the sunflower trial, there were evaluated several morphological parameters and the productivity of six hybrid varieties, five of which recommended for the Portuguese territory (Kiara, P63HH79, Oleko, Fortini and Mooelli) and one for the Angolan territory (Chitra), when cultivated in two seeding densities 40 000 (D4) and 60 000 (D6) plants ha-1. The trial was also established in a rainfed regime. In the soybean trial, the biomass production of a variety recommended for the Angolan territory (Tabarana) was evaluated when cultivated in four seeding densities (133333, 200000, 250000 and 333333 plants ha-1) under irrigation. In rapeseed, the different sowing dates gave significant differences in dry matter yield and nitrogen recovery when evaluated in three sampling dates during the vegetative phase. Nitrogen applied as top-dress (before sowing) did not produce significant differences in dry matter yield and nitrogen recovery in the first and second harvests carried out in the vegetative phase before top-dress N fertilization. In the third harvest after top-dress fertilization, significant differences between fertilizer treatments were already registered. At harvest, different sowing dates revealed significant differences in dry matter yield (straw and grain) and in nitrogen recovery. The earlier the sowing the higher the dry matter yield and nitrogen recovery. Nitrogen fertilization also resulted in significant differences between treatments, with grain yield increasing up to the rate of 100 kg N ha-1. Grain yield reached 6000 kg ha-1 in the most productive plots. The results unequivocally showed great advantages in early sowing. In the region, if possible, sowing should be performed in September. The plant also responded to moderate nitrogen rates. 4 In the sunflower, the different hybrids showed distinct morphological traits regarding the height, stem diameter and diameter of the flower head (capitulum). These parameters also varied significantly as a function of planting density. The plants grown at D4 density were more vigorous, being significantly higher, with greater diameter of the stem and the flower head, and producing more grain per plant. At density D4 the grain yield per unit area tended to be higher than at D6. A significant linear relationship was established between the different parameters of vigor and between these and the grain yield per plant. It should be noted that between the stem diameter and the grain yield per plant, a significant linear relationship was also established with a high coefficient of determination (R2 = 0.79). The most productive variety was Kiara, reaching 2886 kg grain ha-1. In soybean the different seeding densities did not produce significant differences in above-ground biomass production, nitrogen concentration in plant tissues and nitrogen recovery, although the average of these parameters increased consistently with seeding density. This result suggests that it will be possible to obtain better yields with a high seeding density (33.3 plants m-2). However, in the conditions of this experiment the plants did not complete the growing cycle and it was not possible to record the production of grain. In this region growing soybean must be based on early season varieties.
The cultivation of oil crops has increased extraordinarily across the world. The present work reports results of field trials conducted with three important oilseed crops, namely rapeseed, sunflower and soybean. The field trials were carried out from September 2015 to October 2016 in Bragança (Portugal). In the rapeseed trial it was assessed the crop response to three sowing dates (09/25/2015, 10/16/2015 and 11/14/2015) and four nitrogen fertilizer rates (preplant + top-dress: 25 + 125 kg ha-1; 25 + 75 kg ha-1; 25 + 25 kg ha-1 and control, without nitrogen application). The experiment was conducted under rainfed conditions. In the sunflower trial, there were evaluated several morphological parameters and the productivity of six hybrid varieties, five of which recommended for the Portuguese territory (Kiara, P63HH79, Oleko, Fortini and Mooelli) and one for the Angolan territory (Chitra), when cultivated in two seeding densities 40 000 (D4) and 60 000 (D6) plants ha-1. The trial was also established in a rainfed regime. In the soybean trial, the biomass production of a variety recommended for the Angolan territory (Tabarana) was evaluated when cultivated in four seeding densities (133333, 200000, 250000 and 333333 plants ha-1) under irrigation. In rapeseed, the different sowing dates gave significant differences in dry matter yield and nitrogen recovery when evaluated in three sampling dates during the vegetative phase. Nitrogen applied as top-dress (before sowing) did not produce significant differences in dry matter yield and nitrogen recovery in the first and second harvests carried out in the vegetative phase before top-dress N fertilization. In the third harvest after top-dress fertilization, significant differences between fertilizer treatments were already registered. At harvest, different sowing dates revealed significant differences in dry matter yield (straw and grain) and in nitrogen recovery. The earlier the sowing the higher the dry matter yield and nitrogen recovery. Nitrogen fertilization also resulted in significant differences between treatments, with grain yield increasing up to the rate of 100 kg N ha-1. Grain yield reached 6000 kg ha-1 in the most productive plots. The results unequivocally showed great advantages in early sowing. In the region, if possible, sowing should be performed in September. The plant also responded to moderate nitrogen rates. 4 In the sunflower, the different hybrids showed distinct morphological traits regarding the height, stem diameter and diameter of the flower head (capitulum). These parameters also varied significantly as a function of planting density. The plants grown at D4 density were more vigorous, being significantly higher, with greater diameter of the stem and the flower head, and producing more grain per plant. At density D4 the grain yield per unit area tended to be higher than at D6. A significant linear relationship was established between the different parameters of vigor and between these and the grain yield per plant. It should be noted that between the stem diameter and the grain yield per plant, a significant linear relationship was also established with a high coefficient of determination (R2 = 0.79). The most productive variety was Kiara, reaching 2886 kg grain ha-1. In soybean the different seeding densities did not produce significant differences in above-ground biomass production, nitrogen concentration in plant tissues and nitrogen recovery, although the average of these parameters increased consistently with seeding density. This result suggests that it will be possible to obtain better yields with a high seeding density (33.3 plants m-2). However, in the conditions of this experiment the plants did not complete the growing cycle and it was not possible to record the production of grain. In this region growing soybean must be based on early season varieties.
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Brassica napus Helianthus annuus Glycine max índice de colheita