Diogo Carneiro de Santana

Lixiviação e degradação de diuron em dois solos de textura contrastante

This research was aimed at studying the leaching of diuron in soil columns, as well as the effect of different methods of reduction of microbial activity on diuron degradation in samples of a sandy loam soil (LVd) and a clay soil (LRd). To measure the downward movement of diuron (0; 1.6 and 3.2 kg ha-1), water layers of 0, 20 40, 60 and 80 mm were applied. For degradation studies, the methods used to restrict were as follow: sterilized in autoclave, methyl bromide application, amoxicillin, captan and amoxicilin+captan; soil samples were kept with or without light incidence. Water depths > 60 mm were enough to promote observable leaching in LVd samples. For clay soil, regardless of the water layer applied, herbicide movement was limited to the superficial soil layer. In degradation studies, biomass accumulation of bioindicator Brachiaria decumbens was higher in LRd samples with no restriction. LVd soil samples treated with any microbial activity restriction methods and exposed to light led to bioindicator biomass reduction, in comparison to others treatments. For both soils, biomass of B. decumbens was increased in soil samples that remained exposed to light.

EXTRATOS AQUOSOS DE Xylopia aromatica E Annona crassiflora SOBRE CAPIM-MARANDU (Brachiaria brizantha) E SOJA

The inhibitory effect of Xylopia aromatica and Annona crassiflora (Annonaceae) aqueous extracts on marandu grass (Brachiaria brizantha) and soybean (Glycine max) was evaluated. For such purpose germination tests (25 oC and photoperiod of 12 h) and radicle and hypocotyl development (25 oC and photoperiod of 24 h), were measured during 10 days. Extracts were obtained through plant infusion in distilled water for 24 h. Treatments were arranged in 3 x 6 factorial scheme in randomized block design using four replications. Extracts of seeds, leaves, and branches of X. aromatica or A. crassiflora were used in the concentrations of 20, 40, 60, 80 and 100 g dm -3 , besides an absolute check in distilled water. With exceptions of the extracts with 20 g dm -3 (branches of X. aromatica and A. crassiflora) and 40 g dm -3 (leaves of X. aromatica), all treatments with aqueous extracts inhibited germination of B. brizantha, showing the allelopathic activity of X. aromatica and A. crassiflora. It was verified that extracts of A. crassiflora interfered on the radicle development of B. brizantha. However, only seeds extracts of A. crassiflora interfered in the soybean germination. Key-words: Allelopathy; development; Glycine max; forage grass.