The methanol extract of Rumex nepalensis Spreng. roots at the oral dose of 100-400 mg/kg exhibited significant and dose-dependent purgative activity. 相似文献
Shoot anatomical features viz., number of vessel elements, width and length of vessel and fibre elements were studied in relation
to juvenility/maturity of teak (Tectona grandis Linn. f.). The findings show significant differences in these features, which indicates that variation in shoot anatomy can
be used as a reliable indicator of juvenility/maturity in teak. The effect of age of donor plants and application of auxins
on adventitious root formation in single noded leafy stem cuttings of teak was also investigated. Aging of donor trees suppressed
rooting and sprouting of cuttings, but increased callus formation at the base of cuttings. Per cent rooting and per cent sprouting
in cuttings decreased as age of donor plants increased from 2-months to 15-years and up to 30-years. IBA treatment promoted
per cent rooting as well as per cent sprouting, NAA promoted only rooting and it suppressed sprouting. The effect of auxin
treatment on rooting and sprouting of teak stem cuttings varied with the age of donor plants. Auxin and its concentration,
which suppressed rooting and sprouting in cuttings of younger donor plants, actually promoted rooting when cuttings were taken
from more mature donor plants. It appears that the auxin requirement for causing and promoting rooting in teak cuttings increased
with increasing age of donor plants. The higher auxin requirement for causing and promoting rooting in cuttings of older trees
may be due to a decrease in the content on endogenous auxins or decreased sensitivity of aging tissues to rooting promoters
and /or accumulation of inhibitory substances which inhibit rooting. 相似文献
A study conducted to assess the floor vegetation shows the presence of 17 species underPopulus deltoides in comparison to 28, 29 and 35 underAlbizia lebbeck, Dalbergia sissoo and mix-culture plantations, respectively. Further, the biomass and density of floor vegetation is considerably reduced underP. deltoides compared to other plantations. In addition, the indices for species richness, evenness, dominance and diversity are also
reduced underP. deltoides showing some inhibitory mechanism being operative under these plantations. Based on available literature, allelopathy is
speculated to be responsible for this reduction. 相似文献
Physical characteristics, amino acids composition, protein profiling, pasting characteristics, and phenolic compounds of brown rice (BR) and germinated brown rice (GBR) from different paddy cultivars (PB1, PS44, PB1509, PB1121, and PS5) were investigated. L* (lightness) decreased, but a* (redness and greenness) and b* (yellowness and blueness) increased with germination. Protein and ash content increased, whereas fat and amylose contents decreased with germination. GBR showed lower hardness and gumminess than BR. Foam stability and water absorption capacity from GBR flour were higher compared with BR flour. Accumulation of γ‐aminobutyric acid, histidine, arginine, proline, methionine, and acidic amino acids increased significantly with germination, and increase was related to change in accumulation of glutelin and prolamins. The accumulation of prolamins and glutelin acidic and basic subunits decreased with germination. GBR flour showed lower pasting viscosities compared with BR flour. Ferulic acid, p‐coumaric acid, and quercetin were present in both fractions of the bound form. GBR showed improved nutritional quality that varied in different cultivars. PB1121 was observed to be the best for producing GBR owing to greater changes brought in protein content, essential amino acids, catechin, chlorogenic acid, protocatechuic acid, vanillic acid, and foam stability. 相似文献
Intensive long-term management practices in forest ecosystems can markedly influence soils’ physicochemical and microbial properties. However, their effects on the magnitude of nutrient pools and activities of enzymes regarding nutrient cycling in subtropical forest soils remain unclear. This study aimed to examine effects of long-term intensive management (organic mulching and chemical fertilization) on concentrations of different C, N, and P fractions and activities of enzymes involved with nutrient cycling in a subtropical Lei bamboo (Phyllostachys violascens) forest soil.
Materials and methods
Soil samples were taken from a chronosequence of Lei bamboo forests with intensive management spanning 0, 5, 10, and 15 years. Concentrations of various forms of C, N, and P, as well as activities of β-glucosidase, cellobiohydrolase, urease, protease, and acid phosphatase were measured.
Results and discussion
The results revealed that the concentrations of different classes of C (water-soluble organic C, hot-water-soluble organic C, and readily oxidizable C), N (NH4+-N, NO3?-N, and water-soluble organic N), and P [resin-inorganic P (Pi), NaHCO3-Pi, NaHCO3-organic P (Po), NaOH-Pi, NaOH-Po, HCl-Pi, and residual-P] were enhanced markedly with prolonged duration of intensive management. Furthermore, activities of β-glucosidase, cellobiohydrolase, urease, protease, and acid phosphatase were increased following a 5-year treatment, while they were markedly reduced from 5- to the 15-year treatments. The 15 years of intensive management significantly reduced microbial biomass C and N concentrations by 8.2% and 31.9%, respectively, compared to the control.
Conclusions
We concluded that long-term intensive management led to the accumulation of C, N, and P, while it negatively impacted microbial biomass and activities of enzymes involved in nutrient cycling in subtropical Lei bamboo forest soils. Consequently, a reduction in chemical fertilizers should be considered toward the long-term sustainable development of subtropical Lei bamboo forests.
Maintenance of tropical soil quality for crop production without damaging the environment is a challenge and thus the development of an efficient nutrient-management technique is important. Soil amendment by organic manures has been widely accepted as an efficient nutrient-management technique in tropical agriculture. In this study, a long-term laboratory experiment was conducted to investigate the influence of organic manures of different sources (e.g. cattle manure, poultry manure, vermicompost and oil cakes) on changes in pH, electrical conductivity, organic C and nutrient content (mineral N, available phosphorous and potassium) in tropical alluvial soil. Applications of organic amendments in this study indicated considerable changes in the basic soil physico-chemical properties and different nutrient levels. Soil pH declined slightly, whereas organic C and all the other nutrients increased distinctly, due to the application of organic manures. Thus, the magnitude of changes in the soil properties was dependent on the nature of the organic manure. 相似文献
Field experiments were conducted during the wet seasons of 1991,1992 and 1993 at the Abubakar Tafawa Balewa University Farm, Bauchi (10 ° 22'N, 09 ° 47'E) to study the response of sunflower ( Helianthus annaus L.) to N rates and plant population under rainfed conditions. Four N rates (0, 50, 100 and 150 kg N ha -1) and four plant populations (40000,80000,120000 and 160000 plants ha-1) were factorially combined in a randomized complete block design with three replications. Leaf area index, shoot dry weight and seed yield (kg ha-1) increased significantly with increasing N rates from 0 to 100 kg N ha-1. The growth and yield parameters per plant decreased significantly with increasing plant populations from 40000 to 160000 plants ha-1, but the seed yield (kg ha-1) obtained at 80000 plants ha-1 was significantly higher than all the other plant populations. The interactions of N x plant population confounded the main effect of each factor on the growth and yield of sunflower. The seed yield (3425 kg ha-1) obtained from the use of 100 kg N ha-1 at 80000 plants ha-1 was significantly higher than those obtained from all other combinations of N x population and out-yielded the main effects of 100 kg N ha-1 and 80000 plants ha-1 by 18 % and 25 %, respectively. The use of 100 kg N ha-1 at 80000 plants ha-1 is therefore recommended for maximum yield of sunflower in Bauchi. 相似文献
Summary Reciprocal recurrent selection was carried out with two populations of maize (Zea mays L.) having good combining ability. We selected for higher grain yield, early maturity, shorter plant height and lodging resistance. Two cycles were completed in two years (four seasons), by resorting to late planting of S1 lines for recombination in the main season in which top-cross families were assessed. Top-crosses and selfings were made in the off-season. The original and improved versions of the populations and their crosses were evaluated in multilocation trials. The superiority of the population hybrid was 10.3% for grain yield, 5.5% for plant height and 1.8 days to silk. The improved hybrid had delayed leaf senescence and better resistance to lodging and post-flowering stalk rots. Among the yield components, only ear girth showed improvement. Syn 2 of the improved population cross showed a yield reduction of 6.2% in comparison to Syn 1. Intrapopulation gains were not significant except for lodging resistance in one population. 相似文献