REDUCING NITRATE CONTENT IN LETTUCE BY PRE-HARVEST CONTINUOUS LIGHT DELIVERED BY RED AND BLUE LIGHT-EMITTING DIODES

Effect of pre-harvest continuous light with different red/blue ratio on photon flux density (R/B ratio) on reducing nitrate accumulation was studied by growing lettuce (Lactuca sativa L.) under continuous illumination delivered by light-emitting diodes (LEDs). Results show that nitrate concentration decreased by 1648.0–2061.1 mg kg^?1 in leaf blade and 962.9–2090.3 mg kg^?1 in petiole, accompanied by a dramatic increase in soluble sugar content. Compared with monochromatic red light treatment, the decrease in nitrate concentration and increase in soluble sugar content in lettuce under mixed red and blue light were more pronounced. The lowest nitrate concentration was observed in the treatment with R/B ratio of 4. It's concluded that pre-harvest exposure to 48?h continuous LED light could effectively reduce nitrate accumulation in lettuce and this process is strongly affected by R/B ratio of light. This study may provide new perspective for pre-harvest quality management of vegetable, especially in commercial leaf vegetable production under artificial lighting.     

不同类糖接枝改性对花生蛋白膜物理性质的影响

为了改善花生蛋白膜的性能,利用不同小分子糖对花生蛋白进行接枝改性并将改性蛋白制备成膜,分析了糖接枝对花生蛋白膜的强度、延伸性、透光性、溶解性等物理性质的影响。结果表明:糖类物质能提高花生蛋白膜的拉伸强度,其中木糖改性后蛋白膜强度最高,达未经改性花生蛋白对照膜的1.77倍;葡萄糖对蛋白膜的延伸性影响最大,断裂延伸率最高,达对照膜的1.92倍;木糖能改善花生蛋白膜的耐水性,使膜的溶解性显著下降。综合来看,木糖接枝改善花生蛋白膜性能的效果较好,当蛋白/木糖质量比为10时,蛋白膜拉伸强度为1.48 MPa,断裂延伸率为218.92%,溶解性60.80%,蛋白膜浸泡24 h后仍保持完整膜状态。该研究为花生蛋白膜的性能改善以及进一步开发利用提供理论依据。     

圆盘挖掘式甜菜联合收获机设计与试验

为了缓解中国甜菜收获装备短缺的现状,设计了一种适合国内甜菜种植模式和农艺要求的圆盘挖掘式甜菜联合收获机,并阐述了该机的总体配置及主要部件的结构。该机主要由传动系统、对行装置、挖掘装置、输送分离装置、升运装置等组成。其中,液压控制系统提高了机械的操控性及自动化程度;对行装置减少了甜菜的漏挖,实现了自动对行收获;圆盘式挖掘部件参数的优化设计有效减少了工作阻力,输送分离装置和升运装置中的杆式输送链减少了甜菜的输送损失和含杂。田间试验表明,收获机甜菜收获损失率不大于3.42%,粘土率不大于1.18%,损伤率不大于1.82%,折断率不大于1.6%,含杂率不大于4.86%,符合甜菜收获要求。该研究可为甜菜收获机械设计提供参考。     

不同施肥情况下甘蔗叶片的光谱特征分析及叶绿素含量检测

In order to investigate the visible-NIR spectral features of the leaves of a sugarcane variety(ROC 22), the spectral reflectance and the chlorophyll content were measured in the laboratory, and their correlations were analyzed.Prediction models were built eventually.Results showed that the negative correlations with r greater than 0.8 was found in 527-578 nm and 701-731 nm between spectral reflectance and chlorophyll content.And the red edge position(REP) was also found having high correlation with chlorophyll content, with the highest r of 0.8442.In order to explore the most sensitive bands for normalized difference vegetation index(NDVI), 48471 NDVI values were computed with different wavebands for each sample and their correlations with chlorophyll were also analyzed.The distribution maps of NDVI and its correlations in a two-spectral-dimension space both indicated that the red bands had significant influence than the NIR bands.The suggested sensitive red range was 710-735 nm, especially 720-725 nm; and the sensitive NIR range was from 780-850 nm, which had the higher robustness.The chlorophyll predication model with NDVI(725 and 840 nm) in tillering stage had determination coefficients of 0.7386, and was recommended for guiding the subsequent ridging fertilization.     

Nutrients management strategies to improve yield and quality of sugar beet in semi-arid regions

The objective of this study was to evaluate the effects of organic and inorganic fertilizers on the yield and quality of sugar beet genotypes (Beta vulgaris L.). Therefore, a field trial was carried out in Peshawar, Pakistan, during the winters in 2012–2013. The field experiment was conducted in a randomized complete block design with split plots, having three replications. Fertilizer treatments (control, composted manure Higo Organic Plus at 5 t ha^?1, Maxicrop Sea Gold seaweed extract at 5 L ha^?1, farm yard manure at 10 t ha^?1, inorganic nitrogen–phosphorus (NP) at 90:60 kg ha^?1, NP at 120:90 kg ha^?1 and NP at 150:120 kg ha^?1) were allotted to main plots, while genotypes (Sandrina, Serenada and Kawe Terma) were allotted to the sub-plots. Plots treated with the application of NP at 120:90 kg ha^?1 produced the highest beet yield (76.4 t ha^?1) and sugar yield (11.1 t ha^?1), and had the second highest polarizable sugar content (14.52%) and more economic return (Rs. 553,000 per hectare) as compared to control plots. Sugar beet genotype Serenada had significantly higher beet yield (55.5 t ha^?1) and sugar yield (7.9 t ha^?1) and a higher economic return (Rs. 380,000 per hectare) than the other genotypes. Sugar beet genotype Serenada supplied with NP at 120:90 kg ha^?1is recommended for the general cultivation in the agro-climatic conditions of Peshawar valley.     

Specific Responses of Soil Microbial Residue Carbon to Long-Term Mineral Fertilizer Applications to Reddish Paddy Soils

Mineral nutrient inputs to soil may alter microbial activity and consequently influence the accumulation of microbial residues. In this study, we investigated the effects of application rates and ratios of mineral fertilizers on the microbial residue carbon(MRC) of reddish paddy soils after long-term(15-year) fertilizer applications in southern China. Contents of three soil amino sugars as microbial residue contents were determined and MRC were calculated based on amino sugars. Results showed that three individual amino sugar contents increased as fertilizer application rates increased until maximum values were reached at a rate of 450-59-187 kg ha~(-1) year~(-1)(N-P-K). The three amino sugar contents then declined significantly under the highest mineral fertilizer application rate of 675-88-280 kg ha~(-1) year~(-1)(N-P-K). In addition, to enhance the microbial residue contents, it was more beneficial to double P(N:P:K= 1:0.26:0.41) in fertilizers applied to the P-deficient reddish paddy soils than to double either N(N:P:K = 2:0.13:0.41) or K(N:P:K= 1:0.13:0.82). The contents of the three individual amino sugars and microbial residues under different fertilizer application rates and ratios were significantly and positively correlated with soil organic carbon(SOC), total N, total P, and p H. Increases in values of the fungal C to bacterial C ratios showed that soil organic matter(SOM) stability increased because of the fertilizer applications over the past 15 years. The contents and ratios of amino sugars can be used as indicators to evaluate the impact of mineral fertilizer applications on SOM dynamics in subtropical paddy soils. The results indicated that fertilizer applications at a rate of 450-59-187 kg ha~(-1) year~(-1)(N-P-K) may improve crop yields, SOC contents, and SOC stability in subtropical paddy soils.     

Application of biochar in mitigation of negative effects of salinity stress in wheat (Triticum aestivum L.)

Salinity is a major abiotic stress that affects crop production throughout the world. Biochar is an activated carbon soil conditioner that can alleviate the negative impacts of salinity. The research was conducted to evaluate the ameliorative effect of 1% and 2% of biochar application on wheat seed germination and growth attributes under salinity. Both levels of biochar improved the germination and growth conditions under salinity; however, 2% biochar level was more effective compared to 1% level. Root and shoot length increased up to 23% and11% with 2% biochar, respectively. The maximum increase of 16% and 10% in leaf water potential and osmotic potential was noted with 2% biochar at 150 mM salt. The decrease in proline content and soluble sugar at 2% biochar was 51% and 27%, respectively. Decrease in superoxide dismutase activity was 15.3% at 2% level of biochar under stress biochar mitigates the negative effects of salinity and improved wheat productivity.     

外源性环核苷酸调控哈白兔血脂、血糖及血蛋白的动态变化研究

为了研究外源性环核苷酸对动物体内血脂、血糖及血蛋白的动态变化规律的调控作用,本研究以哈白兔为试验动物,通过注射外源注射环鸟苷酸、环腺苷酸及其等量混合物的腹腔注射液,研究了不同处理组4天内不同时间点动物血脂、血糖及血蛋白的动态变化规律。结果发现： cGMP单独处理后,血脂含量大幅度增加,平均增加了17.63％,而经过cAMP处理后的血脂含量有较小幅度的减小;cAMP单独处理后,血糖含量平均增加了1.79％,而cGMP单独处理后血糖含量明显增加,增加率超过了10％;经过cGMP,cAMP和混合处理后血蛋白平均增加率大约为5％左右。此外,cGMP对促进脂肪的合成代谢有明显作用,通过注射cGMP在10h内对血脂没有影响,10～21h对血脂的合成有显著促进作用,21h后血脂才保持一定的增加幅度;而cAMP对降解有较小作用,通过注射cAMP在45h以内对血脂有降解作用,而45～65h又转为合成作用,65h以后作用消失;注射CNT 6～21h时,糖异生作用促进了动物体内血糖含量的增加;注射CNT对血蛋白的作用不明显。这些主要代谢物质的动态变化规律为应用CNT调控动物体内营养物质代谢水平提供了有利的理论依据。     

甜菜耐低温种质筛选和苗期耐冷性鉴定

利用人工气候箱,采取耐低温发芽筛选方法,对50份二倍体甜菜种质进行低温胁迫处理,筛选出耐低温的种质12份,芽期耐冷指数≥0.76。通过苗期耐寒性鉴定发现,这12份种质的苗期耐冷能力与芽期基本一致,但个体间对低温的反应速度及持久性表现存在差异,其中,6份资源具有更强的苗期耐冷能力。试验证明,甜菜种质苗期冷害的生理临界温度为3～6℃,在该低温阈值下,耐冷性强的种质对温度变化不太敏感,而耐冷性弱的资源对温度变化较为敏感。1～2℃是甜菜冷害的发生温度,耐冷性强的资源表现为停滞生长,子叶皱缩卷曲,真叶和下胚轴出现似烫伤表现,逐渐死亡;耐冷性弱的资源受冷害症状较早出现,很快发生畸变和死亡。     

黄芪多糖水提液流变特性研究

粘度是黄芪多糖提取、加工处理过程中的一个重要参数,溶液温度、黄芪总糖含量、浸提温度是重要影响因素.研究结果表明,粘度随溶液温度升高而降低,粘度越大,温度变化对其影响越显著;黄芪总糖含量低于300mg/mL或高于1000mg/mL时,溶液温度对粘度影响较小;浸提温度超过70℃后,不同粒度物料浸提液的总糖含量未增而粘度明显增大,黄芪多糖浸提温度不宜超过70℃.