Growth and biomass of sunflower under different nitrogen levels and available water in the soil of a semi-arid region

Abstract

The adequate water supply and nitrogen in the soil is essential for the growth and development of plants. Sunflower is the target of several studies of such factors due to the economic importance and the needs to expand in the semi-arid regions of Brazil. This work aimed to evaluate the growth variables, measured at 80 days after sowing (DAS), and the biomass obtained at 100 DAS of the Helio 253 sunflower hybrid under the effect of nitrogen and water levels. The experiment was conducted in a greenhouse in the city of Campina Grande- PB, in split-plot of a completely randomized design with four moisture levels in the soil (50, 75, 100 and 125% of available water) and four nitrogen rates (30, 60, 90 and 120 kg ha-1). Among all levels of available water in the soil, the stem diameter (SD) ranged from 13.6 to 19.6 mm and the plant height (PH) from 93 to 107 cm. Plants with 100% AW showed a leaf area (LA) 45% greater than the treatment with higher water stress. The heads had an average diameter between 83 and 98 mm, the dry biomass of the heads (DBC) and total dry biomass (TDB) ranged from 45 to 55 g and of 65 to 101 g, respectively. The weight of a thousand seeds per head (W1000) obtained minimum and maximum of 49 and 66 g. The stem diameter ranged between 14.4 to 18.3 mm and the minimum and maximum plant height values were 93 and 110 cm, using applied N levels. The leaf area varied from 22 to 36 dm2 and the heads had average diameter of 86 to 99 mm. With respect to the dry biomass of the heads, there was a variation of 38 to 68 g and TDB of 68 to 107 g and W1000 valued between 52 and 65 g under doses of N. There is considerable variation in all variables mainly due to increased water level in the soil and nitrogen fertilization.