Andréia Cristina Silva

Produção de palha e supressão de plantas daninhas por plantas de cobertura, no plantio direto do tomateiro

The objective of this work was to evaluate the straw yield, the weed suppression, and the effects of cover crop species on processing tomato (Lycopersicon esculentum) yield, in no tillage system. The treatments evaluated were Crotalaria juncea, Stizolobium aterrimum, Pennisetum glaucum, C. juncea + P. glaucum, C. juncea + S. aterrimum, P. glaucum + S. aterrimum, spontaneous weed cover, and bare soil. The experimental design was randomized complete blocks with four replicates. The tomato yield was not influenced by cover crops. C. juncea was more competitive than P. glaucum, when intercropped, with larger dry mass accumulation (63%). S. aterrimum had slow initial development and low competitivity with the high weed infestations. P. glaucum and C. juncea, grown alone, together, or with S. aterrimum, had dry matter yield above 20 Mg ha-1 and reduced the emergence and dry matter accumulation of weeds in the processing tomato crop.

Caracteres morfológicos de soja e braquiária consorciadas sob subdoses de fluazifop-p-butil

Pasture degradation is one of the most important problems, affecting directly the sustainability of animal production. As one of the alternatives for the recovery of the degraded pasture, the use of annual crops intercropped with forages has been proposed. However, for the viabilization of the intercropping it is necessary the adequate management of the forage to reduce the competition with the crop, searching both development. The objective of this work was to evaluate the effects of fluazifop-p-butil on the morphology of Brachiaria brizantha and soybean grown intercropped. The experiment was conducted at Coimbra-MG to evaluate six doses of fluazifop-p-butil (0, 18, 36, 54, 72 and 90g ha-1) applied at two times (21 and 28 days after soybean emergence - DAE). Additionally, two control treatments were included: soybean and B. brizantha in monocrop kept free of weeds. The time of application did not affect the efficacy of herbicide doses. The treatment without herbicide or at lower doses, affected negatively the leaf area index (LAI), leaves biomass, stem + petioles biomass and pods biomass of the soybean plants. The LAI, leaves biomass (LB), stems number, stem length and stems biomass (SB) of the B. brizantha, were affected by the doses and time of application. The application at 28 DAE caused more injury to the B. brizantha than at 21 DAE. It was verified that at 53 DAE the doses 0, 18 and 36g ha-1, applied at 21 DAE, and the doses 0 and 18g ha-1, applied at 28 DAE were similar to that of control (B. brizantha monocrop) for SB, LB and LAI. The dose of 36g ha-1 of fluazifop-p-butil benefited the B. brizantha compared to soybean. For the other hand the dose of 54g ha-1 of fluazifop-p-butil benefited the soybean compared to B. brizantha. For the conditions of this experiment, the ideal dose of fluazifop-p-butil for the intercropping establishment was 40g ha-1 of fluazifop-p-butil.

Períodos e temperaturas de pré-resfriamento na germinação de sementes de Leonotis nepetaefolia

The objective of this work was to study beneficial conditions during L. nepetaefolia seeds germination an assay was carried out to study pre-cooling temperatures of 5°C and 10°C for periods of 7 and 14 days, during seeds soaking. After these periods, the seeds were submitted to continuous (20°C) or alternate (20°C night - 30°C day) temperatures. Additionally two controls were studied (20°C e 20°C - 30°C) without pre-cooling. The experimental design was completely randomized, with four replications. Seeds submitted to pre-cooling, as well as the controls did not germinate in continuous temperature of 20°C. The seeds submitted to pre-cooling of 10°C for 14 days provided greater uniformity, final germination percentages (45%) and germination speed index compared to that the control.