Produção de fitomassa e composição bromatológica de milho hidropônico cultivado sob diferentes substratos

Abstract

The objective of this study was to evaluate the effect of the different substrates on the production of hydroponic maize green forage (Zea mays L.) cultivated in the semi-arid region of Pernambuco. The experiment was carried out in a randomized block design. The treatments consisted of sugarcane bagasse (SB) (100%), sugarcane bagasse + sugarcane straw (SBS) (50% + 50%), sugarcane straw (SS) (100%), Calotropis procera SW (CP) (100%) and sugarcane bagasse + Calotropis procera SW (SCP) (50% + 50%), in which corn seeds were sown, both with five replications. The blocks consisted of five flowerbeds measuring 0.5 m wide by 2.5 m length, subdivided into five sub-plots of 0.5 m x 0.5 m (0.25 m²) made with wooden slats arranged in parallel leaving 0.50 m streets between bed flowers for the maneuvers, totaling five treatments and five repetitions. The flowerbeds were lined with black polythene tarps of 15 microns. The density used was 2.5 kg of seeds / m². The corn seeds were previously hydrated by immersion in water for 24 hours before sowing for pregermination. An approximately 3 cm layer of the substrates was placed, followed by irrigation with water to moisten the substrate. The seeds were then manually distributed homogeneously, according to the treatments, and covered with another 2 cm layer of the respective substrates. For fertilization, a commercial solution for hydroponic corn was used. Harvesting was performed on the 15th day after sowing. The production per m² of green phytomass, aerial part green mass, green mass of the substrate with root, dry matter (DM) of the total forage, aerial part DM and root DM of the substrate were determined; analysis of percentage of DM, mineral material (MM) and neutral detergent fiber (NDF) of the complete forage, substrate with root and aerial part. The data were submitted to analysis of variance and Tukey test at 5% of probability. The treatment that CP was used as the only substrate did not present productive responses. There was no significant difference (P> 0.05) for the production of natural matter between the treatments. For the production of DM per m-2 of the complete forage, there was the influence of the substrate (P <0.05), where the treatment with SB presented higher production in relation to the SS, being found the values of 4.83 and 3.64 kg of DM per m2, respectively. The substrate influenced (P <0.05) the production of green mass of the aerial part, where the treatments SB and SCP obtained productive values of 676.25 and 106.25 g.m², respectively. For production DM of the aerial part the values found were 94.06; 69.08; 92.34 and 20.23 g.m-2 for SB, SBS, SS and SCP, respectively. For the green mass production of the most root substrate, there was no significant difference (P> 0.05) between the treatments. The sugarcane bagasse presented better productive response and better composition. The substrate influenced the content of DM and MM of the complete forage and aerial part.