基于近红外光谱的桃果实冷害识别分析

该文采用近红外(near infrared,NIR)光谱技术对水蜜桃低温冷害褐变进行识别分析。分别建立了水蜜桃低温贮藏期间不同冷害阶段的两分类和多分类模型,讨论了不同光谱预处理方法对模型的影响,并比较偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA)、主成分判别分析(principal component discriminant analysis,PCA-DA)、K-最邻近(K-nearest neighbor,K-NN)、簇类独立软模式(soft independent modeling of class analogy,SIMCA)4种建模方法的分类效果。结果表明,采用PLS-DA模型效果最好,两分类和多分类模型的总准确率为分别为0.93和0.71。两分类模型可较准确地对冷害褐变进行快速识别分类,多分类模型可用于水蜜桃低温贮藏期间不同冷害阶段的初步筛查。

Current Situation and Control Measures of Agricultural Non-point Source Pollution in Typical Basin of South China

In view of the serious non-point source pollution of agriculture in the areas where crop production is concentrated in southern China,the present situation of agricultural non-point source pollution in southern watershed and the main technical measures adopted in the practice of comprehensive prevention and control in recent years are analyzed from the perspectives of different pollution sources such as planting,livestock and poultry breeding,aquaculture and village area runoff.From the perspective of functional restoration and optimization of farmland ecosystem,the countermeasures are put forward,such as strengthening the control of high qualityoriented pollution reduction,layout optimization,constructing circulation system and improving management system,constructing comprehensive prevention and control strategies for ecosystem elements and material exchange,energy flow and logistics linkage,information flow exchange,and maintaining and improving the ability of agricultural ecosystem itself to absorb non-point source pollution.

Purification of Starch from Cadmium-Contaminated Rice and Development of Functional Recombinant Rice

In order to provide a new utilization method for cadmium-contaminated rice,a preliminary study of the removal of rice starch cadmium by water,calcium hydroxide,sodium hydroxide and citric acid was conducted,the damage degree of starch was compared by SEM,and then the recombinant rice was obtained by a twin-screw extruder using the starch which met the safety standard.The physical and chemical properties of recombinant rice were analyzed by acid hydrolysis and texture analyzer.The results showed that citric acid was a good rice cadmium removal agent.The quality of recombinant rice prepared from cadmium-removed rice starch was improved;the acid resistance was increased.Heavy metal contaminated rice can be a staple food with better quality and higher value through processing.

Remediation Effects of Water Management and Lime Application on Seasonally-Fallowed Cd-Contaminated Paddy Fields

In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium （Cd） content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2＋, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.

Analysis of Rhizosphere Microbial Community Structure in Different Pathogenesis Stages of Watermelon Fusarium Wilt

High-throughput sequencing technique was applied to analyze the microbial community structure of rhizosphere soil at different stages of watermelon fusarium wilt to find out the difference of dominant microbial community in rhizosphere during the occurrence of watermelon fusarium wilt.Illumina-Hiseq high-throughput sequencing platform was used to sequence 16S and ITS rDNA in rhizosphere soil.The soil was named CK1 before planting,CK2 at peak stage and CK3 at stable stage.The results showed that the soil bacterial diversity was in the order of CK1>CK3>CK2,indicating no significant difference between CK1 and CK3 and a significant difference between CK2 and CK1,CK3.At the genus level,the dominant bacteria were Mizugakiibacter(21.9299%),Rhodanobacter(5.0933%),and Lactobacillus(3.1921%).The diversity of soil fungi was in the order of CK1>CK3>CK2,all showing significant differences.At the genus level,the dominant fungus was Lysurus(54.4601%),Papulaspora(12.4252%),Acrophialophora(3.1729%).The results showed that the diversity and abundance of bacteria and fungi in rhizosphere soil decreased during the peak period of watermelon fusarium wilt.With the gradual stabilization of the disease,the diversity and abundance of bacteria and fungi in rhizosphere soil recovered to a certain extent.

Effects of Winter Planting Milk Vetch on Yield and PartialProductivity of Nitrogen Fertilizer of Machine-transplantedDouble-cropping Rice under Straw Returning to the Field

From 2017 to 2018,the effects of winter planting of milk vetch on yield and partial productivity of nitrogen fertilizer of machine-transplanted double-cropping rice under straw returning were studied in Ningxiang city,Hunan Province.The results showed that the dry matter accumulation,effective panicle,yield and partial productivity of nitrogen fertilizer in the stem,leaf,panicle and aboveground parts of early and late rice treated with winter planting milk vetch and straw returning were signi ficantly higher than those treated with straw returning only.Among them,the effective panicles of early and late rice increased by 2.58%,3.18%(2017)and 5.22%,6.32%(2018),respectively.Yield increased by 11.85%,10.07%(2017)and 12.42%,10.92%(2018),annual partial productivity of nitrogen fertilizer increased by 10.90%(2017)and 11.66%(2018),respectively.In conclusion,winter planting milk vetch under straw returning is beneficial to increase dry matter accumulation,rice yield and partial productivity of nitrogen fertilizer in mechanized double cropping rice.

Storage Characteristics of Five Kiwifruit Varieties in Hunan Province

Five kiwifruit varieties(Hongyang, Donghong, Jinyan, Cuiyu, Miliang1)in Hunan were picked and stored at room temperature. Sensory indicators(softening rate, decay rate, and firmness), nutritional quality(soluble solid content, titratable acid, and VC), tissue cell aging indexes(malondialdehyde, membrane permeability),and activity of polyphenol oxidase(PPO) and peroxidase(POD) during storage were analyzed. Results showed that firmness of Hongyang, Miliang1, and Cuiyu decreased rapidly, particularly Hongyang. The firmness of Donghong and Jinyan decreased slowly, but the decrease of Jinyan was slower than that of Donghong. Softening rate and decay rate were significantly different among the varieties. To be specific, the softening rate and decay rate of Jinyan were lower than those of Hongyang. Soluble solid content rose at early stage and then declined. Soluble solid content was high in Hongyang after storage for 12 d and high in Donghong and Jinyan after storage for 15 d. Content of titratable acid dropped slowly. Maximum VC content of Donghong,Jinyan, and Cuiyu was higher than that of Hongyang and Miliang 1. The inflection point of relative conductivity increase increase of Jinyan appeared later than that of Hangyang. The MAD content of Jinyan and Donghong kept at a low level. Storage characteristics of different kiwifruit varieties were significant. Storage time was in the order of Hongyang < Miliang 1 < Cuiyu < Donghong < Jinyan. In summary,Hongyang, Cuiyu, and Miliang1 should not be stored for a long time, while longterm storage is favorable for Jinyan and Donghong.

Genetic Similarity Analysis of Hunan Rice Landraces with Same or Similar Name in Household and Genebank Conservations

This study was conducted to analyze the phenotypic and genotypic similarity or diversity of rice （Oryza sativa L.） landraces in household and hypothermic genebank conservations in Hunan Province and identify the genetic distance between the rice landraces with the same or similar names. A total of 92 accessions of rice landraces were divided into seven groups according to their local names, but the morphological traits showed large variations even within the same group as well as between household and genebank conservations. The SSR marker analysis showed that, in all the groups except Group E, the allelic variations within each subgroup of the household conservation were less than those of the genebank conservation, indicating the household-conserved rice landraces’ many-generation purifcation from natural and artifcial selections in the process of their cultivation year after year; and the similarity coeffcient among the household rice landraces was the highest except for Groups C and E. Thus, the study suggested that the same-name or similar-name rice resources retained by farmers would be valuable for collection and evaluation.

Effects of Wet Superfine Grinding on Polyphenols and Antioxidant Activities of Whole Fruit Pulp of Navel Orange

The navel orange were cleaned and pulverized by a wet superfine grinding and a broken wall cooking machine,then the navel orange whole fruit pulp were obtained by wet superfine grinding once,wet superfine grinding twice,and broken wall cooking machine processing.The particle size distribution,free polyphenols,bound polyphenols and antioxidant activity of whole fruit pulp prepared by the three kinds of pulverization methods were discussed.The results showed that the particle size distribution of the whole fruit pulp by wet superfine grinding was more concentrated compared with the broken-wall cooking machine processing,and the total phenols dissolution rate of the navel orange whole pulp was increased by 6.9%,and the total flavonoid dissolution rate was increased by 13.5%.The results also suggested that wet superfine grinding twice could improve 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical scavenging activity of polyphenols in the whole fruit pulp,wet superfine grinding once and wet superfine grinding twice also could obviously enhance the reducing power and iron reduction ability of polyphenols in the whole fruit pulp.In conclusion,wet superfine grinding could increase both the polyphenol content and antioxidant activity of navel orange whole fruit pulp,it can be used as a pretreatment processing method for preparing navel orange whole fruit pulp.

Adsorption and Desorption Characteristics of Nitrogen and Phosphorus in Paddy Soils from Different Parent Materials

Reddish clayey soil(HH),alluvial sandy soil(HS),granitic sandy soil(MS)and purple clayey soil(ZS)were used as the test materials to reveal the adsorption-desorption characteristics of nitrogen and phosphorus nutrients in paddy soils from different parent materials.The results showed that the nitrogen desorption amount of each soil was greater than the nitrogen adsorption amount in the low nitrogen concentration range of 0~10 mg/L;in the high nitrogen concentration range of 20~50 mg/L,the soil nitrogen desorption rate gradually decreased with the increase of nitrogen concentration of the equilibrium liquid;when the soil nitrogen adsorption amount was-57.267~352.400 mg/kg,the nitrogen adsorption capacity of the paddy soils from different parent materials was HS>ZS>HH>MS;when the nitrogen desorption amount was 8.367~37.833 mg/kg,the nitrogen desorption capacity of the paddy soils from different parent materials was HH>HS>MS>ZS;the nitrogen adsorption isothermal curves of HH,MS,HS and ZS fitted the Linear model,the correlation coefficients were 0.928~0.978.At the same time,in the range of low phosphorus concentration(0~10 mg/L),the phosphorus adsorption amounts of 4 paddy soils were greater than their phosphorus desorption amounts.When the phosphorus concentration of the equilibrium solution exceeded 10 mg/L,phosphorus fixation capacities of 4 paddy soils weakened,meanwhile their phosphorus desorption increased,but their adsorption amounts were still greater than their desorption amounts.When phosphorus adsorption and desorption amounts of 4 paddy soils were-110.312~534.961 and 0.188~14.320 mg/kg respectively,the phosphorus adsorption and desorption capacities of 4 paddy soils were HS>HH>ZS>MS and ZS>MS>HS>HH,respectively.The phosphorus adsorption isothermal curves of 4 paddy soils fitted the Langmuir and Freundlich models,the correlation coefficient were 0.945~0.995.In general,paddy soils developed from different parent materials in Hunan Province have different adsorption and desorption characteristics for nitrogen and phosphorus.Purple clayey soil has the strongest nitrogen fixation capacity due to its stronger viscosity,which can reduce the risk of nitrogen loss by effectively holding nitrogen in the soil solution.On the contrary,being of strong sandy property,granitic sandy soil has the worst nitrogen fixation capacity and higher risk of nitrogen loss.The four paddy soils have strong adsorption capacity and low desorption rate of phosphorus,which indicates that the main paddy soils in Hunan Province have strong adsorption capacity for phosphorus and relatively small loss risk.

Identification and Expression Analysis of ARF Gene Family in Pepper

In order to understand the functions of ARF（Auxin Response Factor） gene family during the growth and development and under stress in pepper, 20 ARF genes were identified from the capsicum genome by bioinformatics and these genes were not well-distributed on 12 chromosomes of pepper. The results of the phylogeny relationship showed that ARF genes of pepper could be divided into Class I and II and could be further divided into seven sub-groups： Ia, Ib, Ic, Id, Ie, IIa and IIb. The results of gene structure showed that ARF gene family members were composed of 1-15 exons, and for each gene expression level of different tissues at different developmental stages revealed that the gene family had certain expression specificity. The qRT-PCR uncovered that high salt stress could significantly activate and inhibit the expression ofARF gene family.

便携式近红外光谱仪在果蔬品质定性和定量分析中的应用

近红外光谱具有快速、无损、绿色无污染等优点,在果蔬品质的检测和鉴别中发挥着重要的作用。便携式近红外光谱仪器弥补了台式近红外光谱仪不可携带的缺点,避免样品长时间运输后品质发生变化,实现了便携、实时检测的目的,适应了市场的需求。文章对便携式近红外光谱仪的检测原理、仪器类型及特点进行了介绍,同时阐述了便携式近红外光谱仪在果蔬品质定性、营养指标定量等方面的进展,并对便携式近红外光谱仪未来发展趋势进行了展望。