Respostas de populações autógamas de Avena fátua à seleção por baixas doses de diclofop-methyl e glyphosate

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Efeito de extratos de adubos verdes sobre Lactuca sativa e Digitaria horizontalis

Objetivou-se avaliar os efeitos de extratos de quatro espécies de adubos verdes (Canavalia ensiformis, Crotalaria spectabilis, Mucuna aterrimae Sorghum bicolor cv. AG 2005) sobre a germinação de sementes e o crescimento inicial de plântulas deLactuca sativa e de Digitaria horizontalis. Foram realizados dois experimentos: no primeiro, avaliou-se a aplicação das soluções diluídas a 1%, 2%, 3%, 4%, 5% e10% de extratos aquosos da parte aérea e das raízes das espécies de adubos verdes sobre a germinação, índice de velocidade de germinação e o comprimento radicular de L. sativa; no segundo, avaliou-se a incorporação ao solo de 0, 10, 20, 30, 40 e 50 g dm-3 da biomassa dos adubos verdes sobre o acúmulo de massa seca (parte aérea e raízes) e o desenvolvimento radicular de plântulas de L. sativa e de D. horizontalis. Concluiu-se que os extratos aquosos das espécies C. ensiformis, C. spectabilis, M. aterrima e S. bicolor cv. AG 2005 promoveram efeitos negativos sobre a germinação e o IVG das sementes de L. sativa. A incorporação ao solo da biomassa dessas espécies de adubos verdes influenciou negativamente no desenvolvimento inicial das plântulas de L. sativa. Entretanto, verificou-se efeito positivo sobre o desenvolvimento inicial de D. horizontalis com a incorporação ao solo da biomassa de C. spectabilis.

Productivity, Leaf Nutrient Content and Soil Carbon Stocked in Agroforestry and Traditional Management of Maize (Zea mays L.)

The aim of the work was to evaluate the productivity, leaf nutrient content and soil nutrient concentration in maize (Zea mays L.) grown in sequence with black oats (Avena strigosa Schreb.) under Leucaena diversifolia alley cropping agroforestry system (AFS) and traditional management system/sole crop (without trees-TS), after two years of cultivation following a randomized block design. The experiment was carried out in the Brazilian Association of Biodynamic Agriculture, in Botucatu—S?o Paulo, Brazil. Treatments were: control (C), chemical fertilizer application (F), biomass of L. diversifolia alley cropping application (B), biomass of L. diversifolia alley cropping + chemical fertilizer application (B + F). In the second year of management it was observed that black oat yield was higher in treatments B + F and F with significant difference in relation to the others treatments in both systems, followed by treatment B. Between systems, only treatment B showed significant difference, with higher yield value corresponding to AFS, reflecting the efficiency of AFS to promote soil fertility. Maize production presented the second year of cultivation an increasing trend in all treatments in both production systems. This result may be due to the cumulative effect of mineralization and maize straw and oats, along the experiment. How productivity was higher in the AFS system, could also be occurring effect of biological nitrogen fixation, water retention and reduction of extreme microclimate through the rows of L. diversifolia. Comparing the AFS and TS, it was observed that the concentration of N in leaf tissue was higher in the AFS treatments, probably due to nitrogen fixation performed through the rows of L. diversifolia, that is a nitrogen fixing tree species. After two years, carbon stocked in soil show higher values in the treatments biomass + fertilizer and biomass application, in both systems, AFS and TS.