Renan Cantalice de Souza

Eficiência do uso da radiação em cultivos de milho em Alagoas

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 Beers 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.

Phytotoxic Effects of African Mahogany Seedlings to Herbicides

The chemical control of weed is a common practice in silviculture. However, herbicides can potentially damage the main crop and affect its growth. The lack of information about certain species such as Khaya senegalensis make it necessary to know the phytotoxic effects of herbicides. The purpose of this research was to analyze the phytotoxic effects of five herbicides on African mahogany seedlings. The used herbicides were: saflufenacil, amicarbazone, clomazone, isoxaflutole and sulfentrazone, at doses recommended by the Ministry of Agriculture for forest species. Visual, physiological (maximum ETR, SPAD, Yield protocol and FV/FM) and morphological evaluations were performed up to 60 DAA. The symptoms started after 24 hours from the application; saflufenacil and clomazone were the ones that presented more plants with symptoms such as leaf wrinkling and small necrotic spots, but all of them had low phytotoxicity. The physiological evaluations did not present significant differences and the herbicides did not inhibit the growth or the appearance of new leaves. All tested herbicides caused no phytotoxicity to African mahogany seedlings.

Observed and modelled solar radiation components in sugarcane crop grown under tropical conditions

Abstract The net radiation over vegetated surfaces is one of the major input variables in many models of soil evaporation, evapotranspiration as well as leaf wetness duration. In the literature there are relatively few studies on net radiation over sugarcane crop in tropical climates. The main objective of the present study was to assess the solar radiation components measured and modelled for two crop stages of a sugarcane crop in the region of Rio Largo, Alagoas, North-eastern Brazil. The measurements of the radiation components were made with a net radiometer during the dry and rainy seasons and two models were used to estimate net radiation: the Ortega-Farias model and the Monteith and Unsworth model. The highest values of net radiation were observed at the crop development stage, due mainly to the high indices of incoming solar radiation. The daily average albedos of sugarcane at the crop development and mid-season stages were 0.16 and 0.20, respectively. Both models showed a better fit for the crop development stage than for the mid-season stage. When they were inter-compared, Monteith and Unsworth model was more efficient than Ortega-Farias model, despite the dispersion of their simulated radiation components which was similar.

Post harvest of pink ginger floral stems treated with silver thiosulphate, sucrose, and calcium.

O mercado brasileiro de flores tropicais encontra-se em franco crescimento, com uma importante participacao da regiao Nordeste, destacando-se o estado de Alagoas. Dentre as flores tropicais de corte para exportacao, a alpinia (Alpiniapurpurata (Vieill) K. Schum) ocupa posicao de destaque. Visando retardar a senescencia das hastes florais de alpinia, cultivar Pink Ginger, foram conduzidos dois experimentos em laboratorio no CCA da Universidade Federal de Alagoas. No primeiro, foram testados tres tempos (30; 60 e 120 minutos) de exposicao ao tiossulfato de prata 1 mM, seguido ou nao de pulsing em sacarose a 20%, por 12 horas. No segundo experimento foram verificados os efeitos nas relacoes hidricas e longevidade das hastes da adicao de sulfato de calcio a 50 e 100 mM, silicato de sodio a 1,25 e 2,50 mM, alem da interacao sulfato de calcio a 50 mM + silicato de sodio a 1,25 mM, em solucao de manutencao. Nos dois experimentos, a testemunha consistiu da manutencao das hastes em agua 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 desidratacao das hastes. O uso de sulfato de calcio promoveu aumento da durabilidade comercial e melhoria da hidratacao das hastes.