AIMS Agriculture and Food最新文献

Crop yield in sub-Saharan Africa is often limited by low phosphorus fertility. Farmers in the region can apply phosphate rock, which should increase the plant-available phosphorus level, but this may be prone to sorption in acid soils of the Sahel. The objective of this study was to determine phosphorus (P) sorption characteristics of four representative soil series in Sahelian Mali namely, Longorola (Gleysol), Danga (Fluvisol), Niessoumana (Arenosol) and Konobougou (Acrisol) under Tilemsi Phosphate Rock (TPR) treatment. Data for phosphorus sorption was obtained by equilibrating 5 g of soils for 7 days at room temperature in 50 ml of 0.01M CaCl₂ containing six (6) rates of phosphate as TPR (0, 10, 20, 40, 80,160 mg/L). The linear form of the Langmuir equation was used to calculate sorption parameters of the soils. The Gleysol with the greatest clay content had the highest phosphorus sorption maximum which was over three times greater than that of the Acrisol with the least clay content. The sorption maxima in the range of 59–200 mg/kg were well estimated with Langmuir sorption isotherm (R² ≥ 0.78). Soil organic matter and clay contents influenced phosphorus sorption from the TPR. The degree of phosphorus saturation ranged from 2.39 to 6.47 %, being greater in the Arenosol. In a two-season field experiment on the Haplic Acrisol, we tested on maize, the TPR in two forms (powder and pellet) in addition to water-soluble diammonium phosphate at different rates (0, 11 and 16 kg P /ha). The water-soluble DAP and TPR (powder) had similar effects (p < 0.05) on soil P availability but with DAP producing greater grain yields. This shows that application of TPR in powder form can improve phosphorus availability as water-soluble DAP with positive impact on grain yield. The study provides useful information on P sorption characteristics of TPR amendment in the Sahel.

Quality of dried Andrographis paniculata (Burm.f.) Nees materials is important to determine its effectiveness in traditional medicine. The present study aimed to investigate an effect of harvesting age and drying condition on andrographolide content and its consequences on antioxidant and antibacterial activities. The plants were cultivated and harvested at 90,100,115, and 127 days after sowing (DAS) prior to drying under the sun or using hot air oven at 50, 65, and 80 ℃. The results indicated that drying condition significantly influenced andrographolide content, antioxidant capacities, and antibacterial activity of A. paniculata, whereas the harvesting age had no significant impact on those parameters. The andrographolide contents ranged from 0.74–4.11% (w/w) dry weight. The highest andrographolide contents were obtained at 90 DAS/65 ℃, 127 DAS/65 ℃, and 127 DAS/65 ℃. A. paniculata extracts were found to exhibit antibacterial activity against gram-positive bacterial strains (B. cereus, M. luteus, S. epidermidis, and S. aureus), which the highest antibacterial activity was observed at 90 DAS/65℃. The used of hot air oven at 65 ℃ effectively preserved andrographolide content and antibacterial activity of A. paniculata. In contrast, drying at 50 ℃ was the preferable drying condition for antioxidant capacity. The antioxidant activities of A. paniculata extracts ranged from 3.43–26.73 and 1.93–17.28 mg Trolox/g dry weight for DPPH• scavenging activity and FRAP reducing power activity, respectively. Overall, A. paniculata is suggested to dry using hot air oven at 65 ℃ to maintain high levels of andrograhpolide and antibacterial activity. Drying using hot air oven at 50 ℃ is advised, if antioxidant activity is the main focus. Even though the harvesting age is not a key parameter, A. paniculata is suggested to harvest at 50% flowering stage onward for a better total herbage and andrographolide yield.