Effects of Farmyard Manure and Inorganic Fertilizer Application on Soil Physico-Chemical Properties and Nutrient Balance in Rain-Fed Lowland Rice Ecosystem

A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice production system in Fogera plain, northwestern Ethiopia. The study was carried out during the main cropping seasons of 2010 and 2011. Twenty-seven treatments comprising a factorial combination of three rates of FYM (0, 7.5, and 15 t·ha-1), three rates of nitrogen (0, 60, 120 kg·N·ha-1) and three rates of phosphorus (0, 50 and 100 kg·P2O5·ha-1) were tested. The experiments were laid out as a randomized complete block design with three replications. Bulk density, organic matter content, and available water holding capacity, total N, and available P of the soil were measured just after harvesting the rice crop. Results showed that application of 15 t·FYM·ha-1 significantly increased soil organic matter and available water holding capacity but decreased the soil bulk density, creating a good soil condition for enhanced growth of the rice crop. Application of 15 tFYM·ha-1 increased the level of soil total nitrogen from 0.203% to 0.349%. Combined application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 increased the available phosphorous from 11.9 ppm to 38.1 ppm. Positive balances of soil N and P resulted from combined application of FYM and inorganic N and P sources. Application of 15·t ha-1·FYM and 120 kg·N·ha-1resulted in 214.8 kg·ha-1·N positive balance while application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 resulted in a positive balance of 69.3 kg·P2O5·ha-1 available P. From the results of this experiment, it could be concluded that combined application of FYM and inorganic N and P fertilizers improved the chemical and physical properties, which may lead to enhanced and sustainable production of rice in the study area.

Seasonal and Annual Variations of CO_2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

Water use efficiencies of maize cultivars grown under rain-fed conditions

Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/drought and erratic rainfall patterns. This study was conducted to assess the relationship between total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agro-ecological environment of Ghana. Results of the study showed that a unified linear model, WUETDM = 0.03TDM with R2 = 0.765 and P ≤ 0.001, described adequately the relation between wa-ter use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUEGY and GY for the major (WUEGY = 0.001GY – 0.67;R2 = 0.996;P ≤ 0.001) and minor (WUEGY = 0.002GY + 0.289;R2 = 0.992;P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cultivars, re-lating WUEGY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but differently in each of the crop growing seasons as a results of dif-ferences in seasonal rainfall. However, the models could be used to estimate water use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.

Resilience, reliability and risk analyses of maize, sorghum and sunflower in rain-fed systems using a soil moisture modeling approach

This paper is aimed at examining the applicability of methods for resilience, reliability and risk analyses of rain-fed agricultural systems from modeled continuous soil moisture availability in rain-fed crop lands. The methodology involves integration of soil and climatic data in a simple soil moisture accounting model to assess soil moisture availability, and a risk used as indicator of sustainability of rain-fed agricultural systems. It is also attempted to demonstrate the role of soil moisture modeling in risk analysis and agricultural water management in a semi-arid region in Limpopo Basin where rain-fed agriculture is practiced. For this purpose, a daily-time step soil moisture accounting model is employed to simulate daily soil moisture, evaporation, surface runoff, and deep percolation using 40 years (1961-2000) of agroclimatic data, and cropping cycle data of maize, sorghum and sunflower. Using a sustainability criterion on crop water requirement and soil moisture availability, we determined resilience, risk and reliability as a quantitative measure of sustainability of rain-fed agriculture of these three crops. These soil moisture simulations and the sustainability criteria revealed further confirmation of the relative sensitivity to drought of these crops. Generally it is found that the risk of failure is relatively low for sorghum and relatively high for maize and sunflower in the two sites with some differences of severity of failure owing to the slightly different agroclimatic settings.

Carbon Budget Dynamics over a Rain-Fed Maize Agricultural Ecosystem in Northeast China and Its Regulation

Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study. We found that the average carbon budget of non-growing season, growing season and annual were 153.16 - 202.03 g C/m2, −689.36 - −488.17 g C/m2, and −316.96 - −487.33 g C/m2, respectively. Maize carbon content of grain yield was −226.6 - −339.94 g C/m2, accounting for 55.4% of carbon budget in the growing season. From sowing to seven-leaf stage, the carbon budget of this ecosystem was characterized by carbon release, with the rate of 0.028 ±0.0056 mg CO2 m−2⋅s−1. From seven-leaf to mature stage, the carbon budget was characterized by carbon absorption, with the rate of −0.256 ±0.0693 mg CO2 m−2⋅s−1. The key meteorological factors affecting annual carbon budget included daily average temperature (R = −0.81, P = 0.03) and saturated vapor pressure deficit (R = −0.64, P = 0.12). At the same photosynthetically active radiation (PAR) level, CO2 assimilation rate was linearly correlated with leaf area index (P 【0.05), and the slopes increased with PAR, indicating the increase in net ecosystem CO2 exchange in growing season was unlikely to be resulted from the extension of growing season. On the contrary, the carbon sink of rain-fed maize ecosystem in growing season might be decreased by extending the growing season ahead of the sowing date.

Analysis and Forecasting of the Impact of Climatic Parameters on the Yield of Rain-Fed Rice Cultivation in the Office Riz Mopti in Mali

During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.

A Multi-Site Case Study on Social Vulnerability to Climate Change of Select Rain-fed Farming Communities in the Philippines

This study examines social vulnerability by exploring the socio-economic factors, infrastructures, and social networks that can determine how prone and how prepared the rain-fed farming communities are to the adverse impacts of climate change. Increased variability in climatic conditions due to climate change seriously affects the productivity of rain-fed farms. The rain-fed farming communities in the Philippines are located in poor and environmentally fragile rural areas. Their vulnerability is greatly affected by restricted entitlement and access to social and economic capitals. This study is framed on qualitative approach to provide a rich and in-depth understanding on the elements of vulnerability based on the capacities and the practical affairs of life in rain-fed communities. The three subject communities from two agricultural provinces are examined to understand how the context and interactions of people can explicate sociological themes on the social dimension of climate change. The usefulness of multi-site study in probing the unique ways of how people understand and respond to certain environmental issue is part of reflections about the methodology.

Effect of Inorganic and Organic Fertilizers on Growth and Yield of Two Industrial Potato Varieties (Asterix and Courage) in Bangladesh

Potato is one of the most important vegetable crops, which contributes more than half of the total vegetable production in Bangladesh. Four field experiments were conducted in two different locations in Bangladesh to develop integrated nutrient management practices to produce quality potato seed in industrial processing varieties Asterix and Courage. For the inorganic trial, Factorial Randomized Complete Block Design (RCBD) including 2 potato varieties, 5 treatments with 4 replications, and in the organic fertilizer trial, Factorial RCBD including 2 potato varieties, 6 treatments with 4 replications were used. In the inorganic fertilizer trail, the highest yield was obtained in the variety Asterix due to Nitrogen, Phosphorus, Potassium, and Sulfur (NPKS) plus Magnesium treated plot in Domar BADC farm and due to NPKS plus Boron, Zinc, and Magnesium treated plots in Kashimpur Farm. In the case of variety Courage, the highest yield was found in the treatment of NPKS plus Zinc in Domar BADC farm while in Kashimpur farm, NPKS plus Mg treated plots had the highest yield of potato variety-Courage. In the organic fertilizer trail, the highest tuber yield per hill was obtained by applying the government-approved commercial brand Northern organic fertilizer in variety Asterix and by organic fertilizer brand Chook Chook in variety Courage. Parameters such as days to tuber initiation, number of stems per hill, plant height, and number of tubers per hill were found statistically different among the treatments and between the two varieties. Treatments namely Northern organic fertilizer and Cowdung combined with mustard oil cake performed better considering standard grade tuber yield (grade A and B) compared to other treatments. Hence, the combination of NPKS MgZn and either Northern organic or Chook Chook or Cowdung plus mustard oil cake could be used to grow the varieties Asterix and Courage.

Metabolic profiles and morphological characteristics of leaf tips among different sweet potato(Ipomoea batatas Lam.)varieties

Sweet potato leaf tips have high nutritional value,and exploring the differences in the metabolic profiles of leaf tips among different sweet potato varieties can provide information to improve their qualities.In this study,a UPLC-Q-Exactive Orbitrap/MS-based untargeted metabolomics method was used to evaluate the metabolites in leaf tips of 32 sweet potato varieties.Three varieties with distinct overall metabolic profiles(A01,A02,and A03),two varieties with distinct profiles of phenolic acids(A20 and A18),and three varieties with distinct profiles of flavonoids(A05,A12,and A16)were identified.In addition,a total of 163 and 29 differentially expressed metabolites correlated with the color and leaf shape of sweet potato leaf tips,respectively,were identified through morphological characterization.Group comparison analysis of the phenotypic traits and a metabolite-phenotypic trait correlation analysis indicated that the color differences of sweet potato leaf tips were markedly associated with flavonoids.Also,the level of polyphenols was correlated with the leaf shape of sweet potato leaf tips,with lobed leaf types having higher levels of polyphenols than the entire leaf types.The findings on the metabolic profiles and differentially expressed metabolites associated with the morphology of sweet potato leaf tips can provide useful information for breeding sweet potato varieties with higher nutritional value.

Highβ-sitosterol-D-glucoside content in sweet potato varieties and its anti-breast cancer potential through multiple metastasis-associated signals

β-Sitosterol-D-glucoside(β-SDG)is a phytosterol compound whose antitumor activity has been confirmed by previous studies.However,its suppression on breast cancer remains unclear.To that purpose,we isolatedβ-SDG from sweet potato and investigated the breast-cancer-inhibiting mechanism using proteomic analysis.The sweet potato species S6 with highβ-SDG content were chosen form 36 species andβ-SDG was isolated by HPLC.Afterwards,an in situ animal model of breast cancer was established,andβ-SDG significantly reduced the tumor volume of MCF-7 xenograft mice.Proteomic analysis of tumor tissues revealed that 127 of these proteins were upregulated and 80 were downregulated.Gene ontology and network analysis showed that regulatory proteins were mainly associated with epithelial-mesenchymal transition(EMT),myogenesis,cholesterol homeostasis,oxidative phosphorylation and reactive oxygen pathways,while Vimentin,NDUF,VDAC1,PPP2CA and SNx9 were the most significant 5 node degree genes.Meanwhile,in vitro and in vivo results showed that the protein expression of PPP2CA and Vimentin,which are markers of EMT,were involved in breast cancer cell metastasis and could be reversed byβ-SDG.This work highlightsβ-SDG as a bioactive compound in sweet potato and the potential therapeutic effect ofβ-SDG for the treatment of breast cancer by inhibiting metastasis.

Effect of Size and Initial Water Content on the Effective Diffusion Coefficient during Convective Drying of Sweet Potato Cut into Cubic and Cylindrical Shapes

In this article, we investigated the influence of size and initial water content on the effective diffusion coefficient of sweet potatoes samples cut into cubic and cylindrical shapes. The sizes of the cubic samples are 0.5, 1, 1.5, 1.75, 2, 2.5 and 3 cm edge with a respective initial water content of 2.7, 3.76, 3.48, 2.68, 3.28, 2.17 and 2.29 kg/kgms. For cylindrical samples, the radius is set at 0.5 cm and sample heights are 1, 1.5, 2, 2.5, 3, 3.5 and 4 cm with respective water contents of 2.2, 3.19, 2.85, 2.1, 2.17, 2.39 and 2.03 kg/kgms. The effective diffusion coefficients of cubic samples are of the order of 10−10 and 10−9 m2∙s−1 grew with sample edge. As for the cylindrical samples, the effective diffusion coefficients were of the order of 10−9 m2∙s−1 and there was no linear correlation between cylinder height and their effective diffusion coefficient. As for the examination of the initial water content on the effective diffusion coefficient, it turned out that the initial water content had no influence on the effective diffusion coefficient of the sweet potato samples.

Influence of Sanitization Process on Maintaining Sweet Potato Quality for Export

The whole cold-chain for exporting sweet potato(native variety“Abees”),to foreign market included immediate curing operation directly after harvest helped in healing skin texture,however,in order to reduce postharvest soft rot(Rhizopus stolonifer)incidence following trimming,and washing,ultraviolet light(UV-C)treatment was used as a main sanitizer for eliminating the soft rot.Exposure of the roots to UV-C(254 nm)was applied in a UV-C room on freshly harvested and cured sweet potato while rolling up on a movable line at 20 cm distance for 1,2,and 3 hr.As combining UV-C treatment with chlorine(200 ppm)on roots,marked and significant reduction of the total microbial load and Rhizopus potential was achieved on root surfaces respectively compared with chlorine alone.It also reduced soft rot percentage to almost 0%infection.After 3 months of cold-storage,quality assessment of sweet potato showed that root characteristics were markedly maintained.The ability of UV-C light to induce phenylalanine ammonia lyase(PAL)enzyme activity in root tissue and maintain the activities of peroxidase and polyphenol oxidase,however with slight increase,was detected.UV-C caused an increase of phenol content in sweet potato tissue that made an activation of defense reaction against the rot causal pathogen.As the exposure time to UV-C light increased,a higher content of phenols occurred.Moreover,UV-C application caused decrease in sugar content of root tissue that is flavored by soft rot-causal pathogen.

Targeting Cancers: Uncovering the Potential Roles of Potato Tissue Culture as Anti-Cancer Agents - A Secondary Publication

Plant tissue culture is a technique that enhances the quality and quantity of potatoes. Potatoes are a significant crop and are primarily used in the world. It is a staple food in many countries, where millions of tonnes are produced annually. It is an essential source of many nutrients, such as proteins, carbohydrates, vitamins, and beta-carotene. In addition, potatoes are being used as therapeutic agents against cancer and other human diseases as well. Potatoes are on the third list after wheat and rice. To overcome food shortages and malnutrition, there are two methods used for producing potatoes: the first is sexual, which is seed propagation, and the second is asexual, which is plant tissue culture propagation. Conventional potato breeding is a uniform method, but it is unsafe because there is a risk of pathogen attack. In a laboratory setting, the tissue culture of potatoes produced millions of plants with nutrient-rich medium under controlled environmental conditions that prevent pest attacks. Some environmental stresses, such as salinity and water scarcity, affect potato yield and production;however, applying nanoparticles like organic, inorganic, and silicon dioxide enhances potato quality and combats stress. Biotechnology has proven to be helpful in addressing all these issues. This review discusses the significance of potatoes, their production through the tissue culture technique, and the application of nanoparticles to improve the growth, and impact of potatoes on human health.

Effects of Sodium Chloride Stress on Growth of Sweet Potato Plantlets in vitro and Ion Content

[Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sodium chloride with the concentration of 0 mmol/L and 100 mmol/L.After 20 days,Na+ content and Na+/K+ ratio in the roots,shoots and leave were determined by the flame photometer,while dry weight and fresh weight of roots,shoots and leave in different varieties were also studied.[Result]The growth of two sweet potato varieties was inhibited under salt stress,so the plant became shorter,leaf and root became fewer,dry weight of roots and leave decreased,but seedlings of Xu 25-2 were inhibited slightly.Furthermore,Na+ content and Na+/K+ ratio in roots,shoots and leaves of two sweet potato varieties increased.Na+ content of salt-tolerant Xu 25-2 was low in roots,shoots and leaves,while Na+ content of salt-sensitive Triumph 100 was high in shoots and leave of seedlings,but the change range of Xu 25-2 was less than that of Triumph 100.[Conclusion]The lower Na+ content and Na+/K+ ratio in leaves under salt stress were the most important characteristics for salt-tolerance of sweet potato varieties.

Effects of Planting Density on Yield and Sourcesink Characteristics of Sweet Potato[Ipomoea batatas(L.) Lam]

[Objective] The aim was to resolve the issue of sparsely planting （37 500-40 500 plants/hm2） of sweet potato in hilly areas. [Method] The starch-oriented Jishu No.21 and raw-eating oriented Jishu No.22 were studied to explore effects of planting density on yield and sink and source characteristics of sweet potato. [IRe- suit] Leaf area index of Jishu No.21 and Jishu No.22 were increasing upon planting density. Leaf area index of the same planting density showed a single-peak curve. Specifically, leaf area index grew fast during the 40th-80th d after planting, and reached the peak on the 80th d after planting, followed by decreasing. What＇s more, ventilation and sunshine transmission both declined upon planting density, as well as the number of leaf, the number of branch, the length of vine, dry and fresh weights of stem and leaf. When planting density exceeded 75 000 plants/hm2, the yield of sweet potato dropped dramatically. Besides, the optimal planting density tended to be volatile upon cultivars. For example, the range of 45 000-60 000 plants/hm2 is the optimal planting density of Jishu No.21 and the range of 60 000-75 000 plants/hm2 is the optimal planting density of Jishu No.22. [Conclusion] It can be concluded that rational planting densities would well coordinate sweet potato growth of ground parts and underground parts to get a high yield by providing a rational group structure. Considering the optimal planting density differs upon cultivars, it is necessary to take genotype, environment, soil fertility and planting density into consideration in determining planting density.

Review on hygienical components of sweet potato and their functions

Sweet potato not only contains primary materials such as dietary fiber, vitamin and soluble protein, but also provides abundant secondary metabolic products which have hygienical functions, like caffeic acid and caffeoylqinic acid derivatives, and anthocyanins, carotanoids. Many studies showed that many secondary products of sweet potato have hygienical functions as quenching free radicals, antioxidation, and preventing cancer, cardiovascular disease and diabetes. Further understanding of the hygienical functions of components in sweet potato is considered to be one of the important factors for developing new uses of sweet potato.

Cloning of Potato POTHR-1 Gene and Its Expression in Response to Infection by Phytophthora infestans and Other Abiotic Stimuli

A complete cDNA of potato Phytophthora infestans-induced hypersensitive response-related protein gene (POTHR-1) was cloned using rapid amplification of cDNA ends (RACE) strategy according to a fragment sequence which we had cloned using suppression subtractive hybridization (SSH) technique. The potato POTHR-1 gene encodes a protein of 225 amino acids, which shares 81% identity with tobacco hin1 gene-enoded protein (harpin-induced protein). Southern blot revealed that there are two to three copies of POTHR-1 in potato genome. The POTHR-1 gene expression in potato leaves showed that its transcripts accumulated remarkably in leaves after 36 h inoculation with P. infestans. Mechanical wounding and jasmonic acid (JA) could induce the POTHR-1 gene expression and osmotic stress just induce a slight accumulation of POTHR-1 gene mRNA, while salicylic acid (SA) had no detectable function on the induction accumulation of POTHR-1 gene transcripts. The potato POTHR-1 gene may preferentially associate with hypersensitive response (HR) or biotic cell death during interaction between host and pathogen.

Study on Daily Change in Photo-physiological Properties of Potato

[Objective]This study was to reveal the photo-physiological properties and suitable climate conditions for potato growth,so as to improve potato quality and yield by making use of the climate resources in Ningxia Hui Autonomous Region,to intensively develop the special agriculture there to enhance the economic benefit of local people.[Method]Using CIRASⅠ-Portable Photosynthesis System,we measured the daily change of photo-physiological indices of potato and further analyzed their relationship with daily weather change,and investigated the impacts of climate factors including atmospheric temperature,humidity,CO2 concentration and light intensity on various physiological indices of potato at key growth stages（flowering stage and stem-swelling stage）.[Results]The results showed that（1） humidity in experimental field assumed a ＂ U＂ type cosine variation curve,while photosynthetically active radiation and atmospheric temperature presented a reverse variation trend;（2） atmospheric CO2 concentration was positively correlated with intercellular CO2 concentration of potato cells,both assumed double ＂ W＂ type curve for daily change;（3） during growth period of potato,in the sunny days with appropriate relative humidity,physiological indices including photosynthetic rate,transpiration rate and stomatal conductance presented similar change law with environmental factor photosynthetically active radiation,all appearing an ＂ M＂ type curve with double peaks and a typical midday depression;（4） midday depression caused by to higher light intensity always appeared simultaneously with the maximum and minimum of air temperature.[Conclusion]Our results provided scientific basis for the large scale production of potato in Ningxia Hui Autonomous Region.

Effects of Different Storage Temperature on Nutritional Quality of Potato Cultivar Kexin No.1

Objective] This study almed to investigate the effects of different storage temperature on nutritional quality of potato cuItivar Kexin No.1 and expIore the opti-mal storage temperature and time for Kexin No.1 with different uses. [Method] After storage at different temperature （1, 4, 10 and 16 ℃）, changes in dry matter, starch, reducing sugar and protein contents, amyIase activity and germination rate of potato cuItivar Kexin No.1 were observed and analyzed. [Result] Reducing sugar content of Kexin No.1 stored at 1 and 4 ℃ increased significantIy compared with that of Kexin No.1 stored at 10 and 16 ℃. Kexin No.1 stored at 1 ℃ exhibited no chiI ing injury. After storage at 16 ℃, Kexin No.1 began to germinate at 30 d, and the Iength and number of germinated buds increased significantIy with the extension of storage time, dispIaying a significant reduction in moisture content. Kexin No.1 potato couId be stored at 1 and 4 ℃ for more than 120 d without any changes in various indi-cators. Therefore, 1-4 ℃ was the optimal storage temperature for potato cuItivar Kexin No.1. [Conclusion] This study provided theoretical basis and technical support for the optimization of post-harvest storage conditions of potatoes.

Extraction Storage and Qualitative Analysis of Free Radicals Scavenging Substances from Sweet Potato Leaves

[ Objective ] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [ Method ] The extraction and storage conditions for free radicals scavenging substances from sweet potato leaves were optimized by orthogonal test and the bioactive components in extracts were investigated by correlation analysis. [ Result] Sweet potato leaves contain the bioactive substances scavenging DPPH free radical and hydroxyl free radical. Extracting solvent species is the most important factor that influencing extraction yield. The optimal extraction and storage conditions are as following： water as solvent, pH 8.0 of extracting liquid, storage at 25 ℃. There is a good positive linear relationship between the content of total phenols in sweet potato leaves and corresponding scavenging rates against both the DPPH free radical and hydroxyl free radical. For the content of total flavones in sweet potato leaves, just a correlation with scavenging rate against hydroxyl free radical shown in test. [ Conclusion] The phenols in ex- tracts could effectively scavenge both the DPPH free radical and hydroxyl free radical, whereas the flavones in extracts can only function on the hydroxyl free radical.