Comportamento vegetativo e produtividade de girassol em função do arranjo espacial das plantas

Abstract

5RESUMO -A cultura do girassol expressiva nos cenários nacional e internacional devido, principalmente, a possibilidade da utilização do óleo na fabricação de biodiesel. O presente trabalho objetivou avaliar os efeitos de arranjos espaciais das plantas sobre as características vegetativas e a produtividade ABSTRACT -Cultivation of the sunflower is becoming increasingly more significant both in the domestic and international markets, mainly due to the possibility of using the oil for the production of biodiesel. The objective of the present work was to evaluate the effects of spatial arrangements of the plants on the vegetative characteristics and productivity of achenes in the Embrapa 122 variety of sunflower at two cultivation sites. The experiments were carried out in the Experimental Area of the Department of Plant Science on the Pici Campus in Fortaleza, Ceará, Brazil, and the on the Vale do Curu Experimental Farm at Pentecost, Ceará, Brazil. Sixteen treatments were evaluated made up of combinations of four row spacings (0.30, 0.50, 0.70 and 0. m) and four planting densities (30,000, 45,000, 60,000 and 75,000 plants ha -1 ) and divided into four randomised blocks. For the vegetative characteristics, the stalk diameter, stem length, leaf number, leaf area and leaf area index were all determined. At the end of the crop cycle the production of achenes was also evaluated. The experiments were analysed jointly in relation to the cultivation site, the data undergoing variance analysis, and the quantitative factors tested by regression using the F-test (p <0.05) to check the fit of the models. The factors studied do not interact on vegetative behaviour and productivity at the same time, the cultivation site being predominant. Intraspecific competition affects the vegetative behaviour of the sunflower. For spatial management of the crop, line spacing may affect productivity of sunflower achenes, depending on the cultivation site.

Agronomic characteristics and oil content of Brazilian sunflower hybrdids under different sowing densities

“…This possibly occurs due to the increase in plant density, in which they compete with each other for essential elements such as luminosity, affecting the height increase and reduction of stem diameter. The results of this variable can be based on studies conducted by Bezerra et al (2014), which verified significant reductions in SD as a function of the increase of the seeding density of the sunflower in Fortaleza, which was lower than results found in the experiment. In cultivar M734, the mean values of stem diameter (SD) was adjusted in a quadratic model, where the SD at the density 45,000 plants ha -1 provided better behavior (28.35 mm), decreasing with increasing density of 50 and 60 thousand plants ha -1 .…”

“…Santana et al (2013), reported the production of achenes and sunflower oil in the semi-arid region (averaged 3,167 kg ha -1 ) for cultivation of BRS324 and 1,504 kg ha -1 for M734, wich is higher than the results obtained by the experiment in Toledo. In related work on plant arrangement, Bezerra et al (2014) reported lower productivity than the average production (702.64 kg ha -1 ). They attributed such a low productivity as a function of environmental factors.…”

Densidade de plantio na produção de ervilha-de-vagem

“…Em princípio, o melhor arranjo é aquele que propicia melhor utilização de água, luz e nutrientes, através de uma distribuição uniforme de plantas na área (Bezerra et al, 2014). A redução da área fotossinté-tica pode comprometer a produtividade no estádio reprodutivo (Sá et al, 2004).…”

Análise de crescimento do girassol em função do suprimento de fósforo e boro

“…Contudo, em relação à omissão de P, o fornecimento deste elemento na dose de 40 kg ha -1 promoveu um incremento de 110,5 % na área foliar. Em área experimental cujo solo era um Argissolo Vermelho-Amarelo com 5 mg dm -3 de teor de P e adubação com 50 kg ha -1 de P, Bezerra et al (2014) estudando o comportamento vegetativo e produtividade do girassol Embrapa 122 em função do arranjo espacial das plantas, obtiveram aos 42 dias após semeadura AF de 3 110,3 cm 2 e 2 502,8 cm 2 para densidades de 30 000 e 45 000, respectivamente. Estes valores foram inferiores possivelmente devido ao menor suprimento de P, o que demonstra a importância deste nutriente para que a cultura expresse melhor seu potencial produtivo.…”