Hydroponic corn cultivation is an efficient, fast, and feasible alternative for periods of food scarcity; however, there is still little information on the qualitative and quantitative parameters of the produced biomass, especially with regard to substrates. This study aimed to evaluate the productive and qualitative aspects of hydroponic feed corn grown on different substrates with a cultivation period of 15 days. Four substrates were evaluated: 1) fermented whole açaí seeds, 2) crushed açaí seeds, 3) sugarcane bagasse, and 4) ground Tifton hay, with five replications under a randomized block design. Substrate temperature was monitored during the production period. After harvesting on day 15, roots length (RL), shoot length (SL), biomass dry matter content (BDM), dry biomass yield, forage dry mass productivity, crude protein (CP), and ash content were assessed. There was no correlation of growth period and substrate temperature. RL was not affected by substrates, BDM was lower in treatment 3, CP was not influenced, and ash content was higher in treatment 1. In general, the best development was observed in treatment 1 because of the absence of distinction regarding qualitative parameters (CP and ash) and higher granulometry of whole açaí seeds which affects mass density and substrate aeration, thus allowing higher dry biomass yield.

Chamaecrista rotundifolia is a forage legume little used with Brazilian livestock; however, it has been studied for this purpose for over 40 years in Australia. The aim of this study was to characterize the influence of plant densities of approximately 444,400, 111,100 and 27,800 plants/ha (equivalent to spacings of 0.15 × 0.15; 0.30 × 0.30 and 0.60 × 0.60 m) on quantitative and qualitative parameters of C. rotundifolia grown in pure stands as forage under exclusive cropping for hay. While leaf dry matter yields in the first 93 days after planting ranged from 1.48 to 9.32 t DM/ha, declining to 0.71–4.92 t DM/ha in the subsequent 83 days, crude protein concentration of the material was only 7–8%. Since this species tends to lose leaf during periods of stress, larger paddock studies are needed to determine how well leaf material is retained under conventional hay-making conditions. Optimal stubble height following harvesting should be investigated in an endeavor to increase DM yields at second harvest along with improved survival of plants.

RESUMO: A Chamaecrista rotundifolia é uma leguminosa com uso potencial para a região Amazônica, principalmente para a produção animal, embora ainda pouco estudada. Como é comum em plantas tropicais, a época de corte e consequentemente o avanço da maturidade podem influenciar a qualidade da forragem para os animais, assim, o objetivo foi verificar a produtividade e o valor proteico da C. rotundifolia colhida em três estágios de crescimento. O delineamento foi em blocos ao acaso com sete repetições avaliando-se três épocas de corte correlacionadas ao início do florescimento, ao auge da produção de vagens e na fase de dispersão de sementes, que equivaleram cronologicamente a 48, 91 e 133 dias após o transplantio das mudas, respectivamente. A definição da época de corte para essa leguminosa influencia seu valor nutricional e produtividade, sendo a colheita realizada aos 133 dias a mais indicada por conciliar valor produtivo e qualidade forrageira.