The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P < 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P < 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.

O Pará é o maior produtor brasileiro de mandioca (Manihot esculenta Crantz), a qual e destinada principalmente para a obtenção da farinha de mesa, embora a fécula seja o produto mais nobre extraído das suas raízes. O objetivo deste trabalho foi caracterizar as raízes e as féculas de três variedades de mandioca produzidas no estado do Pará. A análise biométrica constatou que não há um padrão de tamanho e de forma para as raízes de mandioca. As féculas obtidas apresentaram elevada pureza em amido (92%) e foram classificadas como "fécula tipo 1", pela legislação brasileira. De acordo com a microscopia eletrônica de varredura, os grânulos de amido das féculas apresentaram forma arredondada e ligeiramente achatada em uma das extremidades, com superfície lisa e tamanhos diferentes para as três variedades. As temperaturas de gelatinização dos amidos das três féculas (T p = 74,4°C) não apresentaram diferença significativa (p  0,05), porém o amido extraído da variedade Pai Ambrósio apresentou a maior entalpia de gelatinização (∆H gel = 5,88 J/g).

In the northeast semiarid region water with high salt content is very common, which may negatively affect crops growth and development. Thus using possible salt stress attenuators is extremely important because it allows the use of saline waters for agricultural purposes. Among the possible attenuators of salt stress, humic substances stand out. This work was driven in order to evaluate the effect of the application of humic substances as a possible attenuator of salt stress from papaya seedlings irrigation. The experiment was conducted under entirely randomized design with five replications in a 4 x 4 factorial, regarding the four doses of humic substances (5, 10, 15 and 20g), and the electrical conductivity of the irrigation water (ECw 1.5; 3.0; 4.5 and 6 dS m-1). When it irrigates the papaya seedlings with water of 6.0 dS m-1 is recommended dose of 20 g of humic substances, which provided growth. Irrigation of papaya seedlings with high salinity (3.0 and 4.5 dS m-1) allied with application of 20 g of humic substances provide increased CO2 concentration, transpiration rate, instantaneous water use efficiency, carboxylation efficiency and chlorophyll b content, however, stomatal conductance, net photosynthesis and chlorophyll a content are reduced with increase of the ECw.

Salinity is one of the major obstacles to agriculture in semi-arid regions, as it affects the physiological processes, growth, and yield of numerous crops. Hence, the application of salt stress attenuators is of paramount importance, as it enables the use of saline water for agricultural purposes. Among these, humic acid promotes the growth as well as water and nutrient uptake of plants. To this end, the present study evaluated the effects of humic acid on the growth and physiology of Carica papaya seedlings irrigated with saline water. The experiment followed the randomized block design with five levels of electrical conductivity (0.5, 1.15, 2.75, 4.35, and 5.0 dS m-1) and five concentrations of humic acid (0.5, 0.94, 2.0, 3.06, and 3.5 mL L-1). Growth, gas exchange, chlorophyll content, and chlorophyll a fluorescence were evaluated. Irrigation with 4.9 dS m-1 water and application of 3.05 mL L-1 humic acid promoted the growth of papaya seedlings. Irrigation with high-salinity water (4.96 and 3.09 dS m-1) coupled with the application of 3.05 and 2.21 mL L-1 humic acid increased internal CO2 concentration, transpiration, instantaneous water use efficiency, carboxylation efficiency, and chlorophyll b content. Overall, humic acid (3.5 mL L-1) attenuated the deleterious effects of salt stress, promoting the growth and improving the performance of papaya seedlings under moderate salinity (4 dS m-1).

Abstract. The efficiency in the production of seedlings is decisive for the final result of their applicability. Therefore, strategies to ensure a rapid and uniform emergence are necessary, especially when it is associated with sustainable methods. The aim of this study was to evaluate the influence of different water temperatures as overcoming seed dormancy in Mimosa ophthalmocentra Mart. ex Benth., simply and economically, in the Brazilian Semiarid Region. The experimental design was completely randomized with four replications, each one consisting of 50 seeds, which were subjected to six treatments: intact seeds (T1/control) and seeds immersed in water at 55, 65, 75, 85, and 95 °C (T2, T3, T4, T5, and T6, respectively). Sowing was performed in trays under environmental conditions and evaluations were performed daily for 28 days. The emergence percentage, emergence speed index (ESI), and length and dry mass of seedlings were evaluated. Data were subjected to analysis of variance, and the means were compared by Tukey test (p < 0.05). M. ophthalmocentra has tegumentary dormancy, and its emergence was influenced by water temperature. Immersion of seeds in water at 75 ºC for 1 min provided the best result with 60% of emergence, ESI of 2.68, and seedlings with longer lengths and higher dry mass.