Abstract Background Populations of yam dry rot nematodes Scutellonema bradys, Pratylenchus coffeae and P. brachyurus can be sustained on weed hosts. Objective Evaluate the reaction of 10 weeds frequently found in Alagoas to P. coffeae under greenhouse conditions. Methods Two experiments were carried out in a completely randomized design, with 11 treatments, constituted of 10 weed species and the control (Dioscorea cayenensis) with eight replications. Plants were inoculated with 2,000 nematode specimens, nematode populations were evaluated in roots and soil 60 days after inoculation and the reproduction factor (RF) defined as RF = final population/initial population was calculated. Results Euphorbia hyssopifolia showed RF=0 and was considered as non-host, whereas Chenopodium album, Amaranthus sp., Panicum maximum, Eleusine indica, Senna occidentalis, Emilia coccinea and Richardia brasiliensis, showed RF<1, being rated as poor hosts. Ricinus communis and Macroptilium lathyroides showed RF>1 only in the second trial and were classified as good hosts. Conclusion Ricinus communis and M. lathyroides are potential sources of nematode inoculum for dry rot disease development.

O milho foi cultivado em três sistemas de manejo: i) cobertura de capim; ii) plástico na entrelinha e iii) cultivo tradicional (solo nu). Com o objetivo de determinar a eficiência do uso da radiação (EUR) mediram-se componentes da radiação solar (incidente e transmitida) em dossel de milho. A irradiação fotossintética (HF) incidente foi considerada equivalente a 44% da irradiação solar global. A HF transmitida (HFT) foi estimada utilizando-se a lei de Beer para radiação aplicada a um dossel vegetal (HFT = HF exp(-k IAF)), com coeficiente de extinção da luz (k) ajustado de uma função exponencial, que relacionou a fração da HFT (HFT/HF) e o índice de área foliar (IAF). A HF interceptada (HFI) foi calculada por diferença (HFI = HF - HFT). Estimou-se a EUR por meio de regressão linear, forçada a passar pela origem, entre o acúmulo de matéria seca (MS) e a HFI. O k foi de 0,628 com coeficiente de determinação de 0,88. A EUR das plantas da parcela coberta com plástico foi de 3,85 g de MS MJ-1 de HFI, que mostrou eficiência superior à dos demais tratamentos (solo nu 3,31 g MJ-1 e capim 3,58 g MJ-1); entretanto, esta conferiu menor IAF e, consequentemente, teve menos HFI acumulada, o que resultou na menor produção de MS.

Maize was cultivated under three management systems: i) mulching (grass cover); ii) plastic cover in the inter rows and iii) traditional cultivation (bare soil). The components of the incident and transmitted solar radiation in a maize canopy were measured in order to determine the radiation use efficiency (RUE). The photosynthetic irradiation (HF) was considered as 44% of the solar global irradiation. The transmitted HF (HFT) was estimated using Beer's law applied to a plant canopy (HFT = HF exp (-k LAI)), with the light extinction coefficient (k) by fitting an exponential function, which related the fraction of HFT (HFT/HF) and leaf area index (LAI). The intercepted HF (HFI) was calculated by the difference (HFI = HF - HFT). The RUE was estimated using a linear regression (forced to pass through the origin) between the dry matter accumulation (DM) and HFI. The k was 0.628 with the determination coefficient of 0.88. The plants RUE in plots covered with plastic was 3.85 g DM MJ-1 of HFI, showing a higher efficiency compared to other treatments (bare soil 3.31 g MJ-1 and grass 3.58 g MJ -1). However, this promoted lower LAI and therefore had less accumulated HFI, resulting in lower production of DM.

O mercado brasileiro de flores tropicais encontra-se em franco crescimento, com uma importante participação da região Nordeste, destacando-se o estado de Alagoas. Dentre as flores tropicais de corte para exportação, a alpínia (Alpiniapurpurata (Vieill) K. Schum) ocupa posição de destaque. Visando retardar a senescência das hastes florais de alpínia, cultivar Pink Ginger, foram conduzidos dois experimentos em laboratório no CCA da Universidade Federal de Alagoas. No primeiro, foram testados três tempos (30; 60 e 120 minutos) de exposição ao tiossulfato de prata 1 mM, seguido ou não de pulsing em sacarose a 20%, por 12 horas. No segundo experimento foram verificados os efeitos nas relações hídricas e longevidade das hastes da adição de sulfato de cálcio a 50 e 100 mM, silicato de sódio a 1,25 e 2,50 mM, além da interação sulfato de cálcio a 50 mM + silicato de sódio a 1,25 mM, em solução de manutenção. Nos dois experimentos, a testemunha consistiu da manutenção das hastes em água destilada. A massa fresca e a qualidade das hastes foram determinadas a cada dois dias. O tiossulfato de prata, aplicado na forma de pulsing por 60 minutos ou mais, promoveu desidratação das hastes. O uso de sulfato de cálcio promoveu aumento da durabilidade comercial e melhoria da hidratação das hastes.

The Brazilian market of tropical flowers has been growing broadly with a strong participation of the Northeast Region, where the State of Alagoas stands out. Among the exporting tropical cut flowers, pink ginger (Alpinia purpurata (Vieill) K. Schum) has been one of the most promising species. Aiming at delaying senescence in floral stems of pink ginger, two laboratory experiments were carried out at the Agricultural Science Center of the Federal University of Alagoas. In the first experiment, three different exposure periods (30; 60, and 120 minutes) to silver thiosulphate 1 mM were tested, followed or not by pulsing in a 20% sucrose solution, for 12 hours. In the second experiment, we evaluated the effect of adding calcium sulphate 50 and 100 mM, sodium silicate 1.25 and 2.5 mM, and the combination of calcium sulphate 50mM + sodium silicate 1.25mM on the hydric status and longevity of floral stems. In both experiments, the control treatment consisted of keeping stems in distilled water. Fresh biomass and quality of floral stems were determined every other day. Silver thiosulphate applied in pulsing for 60 minutes or more led to stem dehydration, whereas calcium sulphate improved both stem hydration and commercial durability.