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1.
Field experiments were conducted to determine the direct and residual contributions of legumes to the yield and nitrogen (N) uptake of maize during the wet seasons of 1994 and 1995 at the University Farm, Abubakar Tafawa Balewa University, Bauchi, Nigeria, located in the Northern Guinea savannah of Nigeria. Nodulating soybean, lablab, green gram and black gram contributed to the yield and N uptake of maize either intercropped with the legumes or grown after legumes as a sole crop. Direct transfer of N from the nodulating soybean, lablab, green gram and black gram to the intercropped maize was 24.9–28.1, 23.8–29.2, 19.7–22.1 and 18.4–18.6 kg N ha–1, respectively. However, the transfer of residual N from these legumes to the succeeding maize crop was 18.4–20.0, 19.5–29.9, 12.0–13.7 and 9.3–10.3 kg N ha–1, respectively. Four years of continuous lablab cropping resulted in yields and N uptake of the succeeding maize crop grown without fertilizer N that were comparable to the yields and N uptake of the succeeding maize crop supplied with 40–45 kg N ha–1 and grown after 4 years of continuous sorghum cropping. It may therefore be concluded that nodulating soybean, lablab, green gram and black gram may be either intercropped or grown in rotation with cereals in order to economize the use of fertilizer N for maize production in the Nigerian savannah.  相似文献   
2.
Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition.  相似文献   
3.
ABSTRACT

Thermo-chemical conversion of crop residues to produce biochar is an emerging strategy in the context of sustainable phosphorous (P) use and residue management. An incubation study for 90 d was conducted to investigate the effects of rice-residue biochar (0, 10, 20 and 40 g kg?1) in combination with inorganic-P (KH2PO4) (0, 25 and 50 mg kg?1) on phosphorous availability in medium- and high-P status soils. Increasing biochar addition rates alone or in combination with inorganic-P resulted in a significant increase in P pools, i.e. plant available P or Olsen-P (from 8 to 132 mg kg?1 in medium-P and 15 to 160 mg kg?1 in high-P soils), microbial biomass P and various mineral-bound inorganic-P fractions in the order (Ca-P > organic-P > Al-P > loosely held/soluble-P > Fe-P > reductant soluble-P). Further, lower phosphatase activity (19–50%) with increasing rates of biochar addition in both soils elucidates the ability of biochar to act as a long-term source of available P in the experimental soils. The results demonstrate that rice-residue biochar can directly or indirectly enhance the status of available P in soils and hence can be used as a beneficial amendment to meet the crop P demand.  相似文献   
4.
Commercial grade zinc (Zn) sulfate hepta hydrate (ZnSHH) is the most widely used source of Zn in India and several other countries for amelioration of Zn deficiency in crops. However, it releases water of hydration at temperature above 30°C and forms lumps on storage, which make it difficult to handle it and apply in fields. Therefore, conditioning of ZnSHH with ZnO and neem oil reduces the release of water of hydration and prevents lumps formation and can be well stored. Field experiments were conducted at the research farm of the Indian Agricultural Research Institute, New Delhi, India during rice growing seasons (July-November) of 2009 and 2010 to study the effect of conditioning ZnSHH with ZnO and neem oil on growth, productivity and Zn fortification of rice (Oryza sativa) grain and uptake by Basmati rice ‘Pusa 1121’. The experiment was conducted in a randomized block design with 3 replications comprised of 9 treatments of Zn fertilization. The present study shows that when conditioned with 2% ZnO and 4% neem oil ZnSHH improved yield attributes, grain and straw yields, Zn uptake and partial factor productivity (PFP), agronomic efficiency (AE), recovery efficiency (RE), and physiological efficiency (PE) of Zn in Basmati rice ‘Pusa 1121’. In general, ZnO was inferior to ZnSHH. Application of ZnSHH conditioned with 2% ZnO and 4% neem oil can be a better source of Zn for transplanted puddled Basmati rice on Zn deficient soils.  相似文献   
5.
With continuous outbreaks of stripe rust (Puccinia striiformis f. sp. tritici) epidemics and rapid breakdown of deployed resistance in bread wheat (Triticum aestivum L.) cultivars in North West Plains Zone (NWPZ) in India warrant knowledge and deployment of new and durable sources of resistance to stripe rust. Bread wheat cultivar PBW 343, until recently the most widely cultivated wheat variety in India, is now highly susceptible to stripe rust (score 9 on a 1–9 scale), whereas PBW 621 (score 5.05–5.65) and HD 2967 (score 5.40–6.20) show low levels of resistance. We conducted an experiment, spanning three crop seasons (2013–2014 to 2015–2016), in which parental lines, F1 and F2 populations, F3 and F4 families from two bread wheat crosses, PBW 621/PBW 343 and HD 2967/PBW 343 were generated and evaluated for stripe rust resistance against a virulent pathotype. While the F1 revealed partial dominance, the segregation pattern for stripe rust resistance in F2 and F3 showed transgressive segregation for resistance in both crosses. Chi-square analysis indicated that resistant segregants possessed two genes, one contributed by PBW 621 or HD 2967 (depending on the cross) and the other, unexpectedly but obviously, came from the most susceptible cultivar, PBW 343. Possible genetic mechanisms for this residual resistance and implications for breeding programs are discussed.  相似文献   
6.
There is little available information on the effects of temperature and CO2 enrichment on stomata anatomical characteristics of plants. Effect of these two microclimates was studied on five rose (Rosa spp.) cultivars, viz. ‘First Red’ (used as check), ‘Arjun’, ‘Raktima’, ‘Raktagandha’ and ‘Pusa Pitamber’. Budded, single-stemmed rose cultivars having five lateral buds were grown in controlled environment growth cabinets under enriched CO2 (1000 μmol mol−1) and optimum (28/18 °C, T0) or high (35/25 °C, T1) temperature for 50 days. All observations were made on the abaxial leaf surface. Significant increases in stomatal density (68.7%), index (29.6%) and epidermal cell density (37.3%) were recorded in plants grown at high temperature over control with CO2 enrichment. The cultivars responded differently in terms of length and width of guard cell and stoma (pore) under high temperature, however, the values averaged over treatments showed a significant reduction in these parameters. Further, number of stomata per leaf was higher (28.3%) in plants grown at high temperature, except First Red. A reduction in mean leaf area (26.7%) and dry mass (32.0%) was recorded at high rather than optimum temperature. The specific leaf area was maximum in Arjun (87%) while in First Red, a 14% reduction was noted at high temperature.  相似文献   
7.
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   
8.
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   
9.
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   
10.
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   
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