Produção e composição física da planta de milho para silagem, cultivado em dois níveis de adubação associado a dois espaçamentos entre linhas e duas densidades de plantio

Abstract

The objective was to evaluate the biomass production, the physical composition of the corn plant and its substance content in the dry phase of it and the structural components of the hybrid corn SG-6418 for silage, that was cultivated in two levels of fertilization (low level: 250 kg.ha?¹ of fertilizer + 150 kg.ha?¹ of urea and the high level: 500 kg.ha?¹ of fertilizer + 300 kg.ha?¹ of urea), associated in two row spacing (0.4 and 0.8 m) and two planting densities (50 and 70 thousand plants.ha?¹). The corn plants were weekly evaluated from the flowering until the physiological maturity, on five different dates to evaluate the dry substance content of the plant and its structural components. For the variable height of the ear of corn, the higher values (P<0,05) was observed for the corn grown with low fertilizer facing high fertilization (1,27 contra 1,15 m), while the plant height and the number of dry leaves did not suffer interference (P <0.05), showing average values of 2,05 e 3,89 leaves per plant. The corn, regardless of the level of fertilization, cultivated with row spacing of 0.4m and 70,000 plants.ha?¹ had greater (P <0.05) production of green matter (54310 kg.ha?¹), of dry one (20305 kg.ha?¹) and the grains (10572 kg.ha?¹), compared to the other associations of cultivation, which did not manifest differences between them (P> 0.05). The corn cultivated at a low level of fertilization in spacing of 0,8 m and the lower density of plants shows a lower participation of culm on a dry basis (22,6%) and leaves (16,5%), but with greater participation of bracts and cob.When was increased the plants density, it results an increase participation of culm and leaves and the reduction participation of bracts and cob. The same occurred in the participation of grains in a dry basis by increasing the plant density was a reduction of 42,0 to 27,6%. The cultivation system with a high level of fertilization and spacing of 0.8 m improved the results of the silage quality, by reducing the content of "FND" and "FDA" compare to other fertilization levels of combinations, spacing between rows and planting density. The high level of fertilization changed the characteristics of the corn ear obtained with the increase number of grains in the row, besides the ear length, the perimeter of the ear and corn ear weight in relation to the low level. Based on the results obtained, concludes that the increases in fertilization of corn for silage resulted in higher yields and better quality forage.