Ca(NO3)2 canopy spraying during physiological fruit drop period has a better influence on the tree character and fruit quality of Newhall navel orange(Citrus sinensis Osbeck)

This study aimed to provide a theoretical basis for adopting suitable cultivation measures to tackle calcium （Ca） deficiency in citrus leaves. The Newhall navel orange （Citrus sinensis Osbeck） canopy was sprayed with 20.0 mmol L-1 of Ca（NO3）2 during physiological fruit drop period, fruit expanding period, and fruit maturing period on 30, 90, and 210 days after full bloom （DAFB）, respectively, and its effects on leaf gas exchange parameters and leaf mineral nutrition and fruit quality were analyzed. The results showed that： （1） The photosynthetic rate （ACO2） at 9：00 a.m. and 16：00 p.m. of fruit expanding period with 30 and 90 DAFB Ca（NO3）2treatments slightly or significantly improved mainly by decreasing stomatal limitation and nonstomatal limitation, respectively. （2） Compared with control （CK）, the Ca concentration in leaves with 30, 90, and 240 DAFB Ca（NO3）2 treatments increased by 127.16; 97.53, and 33.33%, respectively, and the leaf magnesium concentra- tion also increased by more than 32.26%. However, Ca（NO3）2 canopy spraying on 30 DAFB significantly reduced the leaf potassium concentration, by 22.14% compared with CK. （3） Ca（NO3）2 canopy spraying on 30 DAFB decreased the second fruit drop rate by 30.55% and increased the weight per fruit by 25.04%, thus resulting in a significant increase in citrus yield. （4） Spraying Ca（NO3） on 30 DAFB mainly affected the metabolism of titratable acid （TA） to improve the maturity of citrus fruits. Whilst it improved the external quality and the coloring of citrus fruit significantly. Therefore, Ca（NO3）2 canopy spraying during physiological fruit drop period has a better influence on the tree character and fruit quality of Newhall navel orange （Citrus sinensis Osbeck）.

Effect of harvest time on the chemical composition and antioxidant capacity of Gannan navel orange(Citrus sinensis L. Osbeck 'Newhall')juice

The present study investigates the chemical composition and antioxidant capacity of juice from the Gannan navel orange, which is harvested at one-to two-week intervals during the ripening period. The total soluble solid(TSS), total polyphenol content(TPC), total flavonoid content(TFC), sucrose and hesperidin contents gradually increase with the ripening of the fruit, followed by slight declines at the late maturity stage. Contrary to these observations, the contents of titratable acid(TA), vitamin C(Vc), and limonin trend downward throughout the ripening period. However, the contents of fructose, glucose, and narirutin fluctuate throughout the harvest time. Three in vitro antioxidant assays consistently indicate that the harvest time exerts no significant influence(P>0.01) on the antioxidant capacity. Furthermore, principal component analysis(PCA) and Pearson’s correlation test are performed to provide an overview of the complete dataset.This study provides valuable information for evaluating the fruit quality and determining when to harvest the fruit in order to meet the preferences of consumers. Meanwhile, our observations suggest that the fruits subjected to juice processing should be harvested at the late maturity stage to alleviate the "delayed bitterness" problem without compromising the antioxidant capacity and the flavonoid content in the juice.

Application of Wavelet Transform in the Prediction of Navel Orange Vitamin C Content by Near-Infrared Spectroscopy

This study was to search for an approach for rapid measurement of orange vitamin C （Vc） content. By using different decomposing levels of Daubechies 3 wavelet transform, the near-infrared spectra signals obtained from intact fruits of 100 navel orange samples were denoised, and the results of the predicted Vc contents for the corresponding samples determined by the reconstructed spectra after denoising were validated by means of PLS-CV （partial least squared-cross validation）. It was shown that the prediction effects verified by PLS-CV analysis varied when different wavelet transform decomposing levels were employed. At the wavelet decomposing level 4, the best prediction effect was obtained, with the correlation coefficient R between the prediction and true values being 0.9574 and the expected variance RMSECV being as low as 3.9 mg 100 g^-1. Furthermore, the 11 different approaches for the pretreatment of the near-infrared spectrum were compared. It was found that the calibration model established by PLS using spectra pretreated by wavelet transform denoising provided the best prediction for Vc content, exhibiting the highest correlation between the prediction and true values by cross validation. In conclusion, the near infrared spectral model denoised by means of wavelet transform can be used for accurate, rapid, and nondestructive quantitative analysis on navel orange Vc content.

Constraints of Quality and Marketing of Gannan Navel Orange and Measures for Industrial Development

In order to provide reference for the sustainable development of Gannan navel orange industry,this paper analyzed constraints of quality and marketing of Gannan navel orange. From developing the dominant area of the navel orange and ensuring high quality healthy development of navel orange,it came up with sustainable development recommendations for Gannan navel orange industry,to realize high quality,efficient,and deep development of Gannan navel orange industry in both the area and quantity,and change from simple planting and sales to fresh fruit sales,deep processing,and tourism combined development.

Physiological changes and expression characteristics of ZIP family genes under zinc def iciency in navel orange(Citrus sinensis)

Zinc （Zn） deficiency is widespread among citrus plants, but information about the mechanisms for Zn deficiency response in these plants is scarce. In the present study, different navel orange （Citrus sinensis （L.） Osbeck） leaves with various yellowing levels were sampled in our experimental orchard, and upon estimation of nutrient contents, Zn deficiencies were diagnosed as mild, moderate, and severe. Further analysis of chlorophyll content, photosynthetic characteristics, antioxidant enzyme activities, and expression levels of Zn/Iron-regulated transporter-like protein （ZIP） family genes were conducted in the sampled Zn-deficient leaves. The results showed that chlorophyll contents and net photosynthetic rate （Pn） seemed to decrease with reduced Zn contents. In addition, comparison of severe Zn-deficient and normal leaves revealed that activities of peroxidase （POD） and catalase （CAT） increased significantly, whereas that of Zn-containing enzymes such as Cu/Zn superoxide dismutase （Cu/Zn-SOD） significantly reduced with decreasing Zn contents. As expected, expression of the ZIP family genes, ZIP1, ZIP3, and ZIP4, was induced by Zn deficiencies. These results deepen our understanding of Zn deficiency in citrus plants as well as provide useful preliminary information for further research.

The effects of rootstocks on performances of three late-ripening navel orange varieties

Selection of rootstock is very important for citrus production. Besides its major role on resistance, the rootstock also can affect fruit production and quality. Currently, the main concerns on selection of rootstock for citrus production are compatibility and resistance, due to less information on the impacts of rootstock to the performance of scion varieties. This study aims to provide information on performances of navel orange varieties on different rootstocks. Three late-ripening navel orange varieties(Citrus sinensis var. Powell, Chislett and Banfield) grafted on seven rootstocks(Swingle citrumelo(C. paradisi× P. trifoliata), Carrizo citrange(C. sinensis×P. trifoliata), X639(C. reticulata×P. trifoliata), MXT(C. sinensis×P. trifoliata), Hongju(C. reticulata), Ziyang Xiangcheng(C. junos) and trifoliate orange(P. trifoliata)) were used as plant materials for comprehensive comparison of the performances on tree growth, fruit yield and quality in 21 scion–stock combinations. Investigation was carried out in these combinations in field nine years after planting. Vigorous growth of all the three late-ripening navel orange varieties was observed on Carrizo citrange with the largest canopy volume at 33.34 m3 and the highest yield at 29.43 kg per tree, but a low yield efficiency at 2.87 kg m–3. On the contrary, those on trifoliate orange had the smallest canopy volume at 10.79 m3 and the lowest fruit yield at 12.51 kg per tree, but the highest yield efficiency at 3.95 kg m–3. Rootstocks did not show significant effects on fruit size, fruit shape index, peel thickness and the edible rate of the fruits, but fruit quality was significantly affected by the rootstocks. Fruits from the trees grafted on trifoliate orange presented the best quality with significantly higher total soluble solids(TSS) content than those on Ziyang Xiangcheng and Hongju, and also the highest ratio of TSS/titratable acidity(TA). The TA content was observed from the fruits on X639 at 0.59 g 100 mL–1. Vitamin C(Vc) content of fruits on Hongju was the highest at 49.25 mg 100 mL–1. Growth vigor of the trees was positively correlated with fruit yield at an extremely significant level. The canopy volume was negatively correlated with yield efficiency, but positively correlated with compatibility index. Results of this study indicated that the rootstock has great impacts on the growth vigor of the tree, yield efficiency and quality of the fruit. In order to achieve good quality and yield efficiency for navel orange production, less growth vigor rootstock such as trifoliate orange is highly recommended.

Correlations between Light Rare Earth Elements in Soil and Navel Orange Tree System in Gannan Area

The total content of light rare earth elements( LREEs) in the soil of navel orange orchards of Gannan area is greater than that of heavy rare earth elements( HREEs). Appropriate content of LREE can not only promote the growth of navel oranges,and it is also conducive to human health. On the basis of exploring the correlations between the content of LREE in the soil of navel orange orchards of Gannan area and the contents of LREE in navel orange leaves and fruit,the influence mechanism of LREEs on the quality of navel oranges was revealed. In this study,with two Newhall navel orange orchards with different soil LREEs background levels in Xinfeng County as the research object,the changes in the content of LREE( lanthanum,La; cerium,Ce; praseodymium,Pr; neodymium,Nd) in leaves and fruit of navel orange at different growth stages were analyzed using Inductively Coupled Plasma-Mass Spectrometry( ICP-MS),and the correlations between the content of LREE in the soil,navel orange leaves and navel orange fruit were studied. The results showed that the contents of the four kinds of LREEs in the soil ranked as Ce > La > Nd > Pr,and there were significant differences among them( P < 0. 01). Navel orange leaves and fruit have selective and heterogenic absorption for LREEs. At different growth stages,La showed the highest accumulation amount in the leaves and fruit of navel orange; and the content of LREE in the leaves of navel orange increased first and then decreased,while that in the fruit of navel orange showed continuous decrease. During the migration of LREEs from soil to leaves to fruit,the content of LREE decreased rapidly as the migration distance increased. The accumulation amount of LREE in navel orange was positively correlated with the content of LREE in the soil. The correlation between the content of LREE in the leaves and fruit of navel orange was greatest. Among the four kinds of LREEs,the correlation of La was greatest,followed by Ce,indicating that the accumulation amount of LREE in the navel orange body was affected by the element types.

AFLP and MSAP Analysis of ‘Lane Late’ Navel Orange and Its Bud Sport Pumpkin-like Navel Orange

[Objectives]The paper was to analyze the differences of genes and genome methylation between‘lane late’navel orange and it’s bud sport pumpkin-like navel orange,and to reveal the causes of bud sport.[Methods]Amplification fragment length polymorphism(AFLP)and methylation sensitive amplification polymorphism(MSAP)were used to analyze the differences in genes and genome methylation of‘lane late’navel orange and its bud sport pumpkin-like navel orange.[Results]Gene mutation occurred between the‘lane late’navel orange and its bud sport pumpkin-like navel orange.A total of 15 differential bands were obtained by AFLP markers,and the percentage of polymorphic bands was 6.0000%.Meantime,10 differential bands were obtained by MSAP markers,and the percentage of polymorphic bands was 5.4645%.The semimethylation rate and permethylation rate of‘lane late’navel orange were higher than that of pumpkin-like navel orange,that is,pumpkin-like navel orange had demethylation(demethylation ratio was 1.6393%).[Conclusions]It is proved at the DNA level that the emergence of bud sport pumpkin-like navel orange is due to gene mutation,and the DNA methylation level of the bud sport material has also changed.This study lays a foundation for further exploring the mechanism of bud sport.

Key Points of Ridge Cultivation of Lane Late Navel Orange

Ridge cultivation can effectively enhance soil permeability,promote root development and improve fruit quality. Based on the characteristics of Lane Late navel orange,this paper summarizes the technical points related to ridge cultivation and compares the effects of ridge cultivation and conventional cultivation on the growth,so as to provide guidance for better production practices.

Problems in Development of Gannan Navel Orange and Recommendations

The rapid development of Gannan navel orange industry has made it become a regional superior industry in China. However,with the rapid expansion of the planting scale,the market dilemma of " vast planting but low income" of navel orange growers is increasingly deteriorating,and Gannan navel orange industrial system is to be further transformed and upgraded. Taking the quality and marketing as the bottleneck of industrial development,this paper analyzed factors influencing these two aspects. It came up with recommendations,including building superior regions,improving industrial quality and safety,and stressing multi-dimensional marketing,relying on government,enterprises,scientific research institutions,colleges and universities,non-governmental organizations,and navel orange growers,to promote high efficient and sustainable development of Gannan navel orange industry.

Interprovincial Comparison and Evaluation of Export Competitiveness of Gannan Navel Orange Based on 2011-2016 Data

China's orange export was mainly concentrated in Jiangxi,Guangxi,Guangdong,Yunnan,and Fujian.The annual output of Jiangxi Gannan navel orange ranks first in the whole China,but the export competitiveness is not very prominent.In view of this,this paper compared the regional market advantages,export performance,export growth rate and export price of Gannan navel orange between Yunnan,Guangxi,Guangdong and Fujian.Through comparative analysis,it discussed the main problems in the development of Gannan navel orange.On the basis of learning development experience of orange industry of Guangxi,Guangdong,Fujian,and Yunnan,it came up with recommendations for improving export competitiveness of Gannan navel orange.

Evaluation of Washington Navel Orange Economic Indicators

In Egypt, oranges are the most important citrus crops for local consumption or export. It represents approximately 72.2% of the total Egyptian citrus production in 2019/2020. The main cultivated variety of orange is the Washington navel orange and it is more popular because of its delicious taste, nutrition, and its seedless besides being rich in vitamin C. Washington navel orange is susceptible to fruit cracking, and it is a common physiological disorder that takes place during fruit development. This work aims to investigate the negative effect of fruit cracking in reducing the yield and quality of Washington navel orange produced in Egypt by studying major economic indicators and estimating an economical evaluation of using treatment of Washington navel orange during the period time of 2007/2008 until 2019/2020. Results showed that fruit areas and production of Washington navel orange represented about 52.9% and 53.2% of fruit areas and production of orange during the study period. However, the yield was unstable with a significant annual growth rate of about 1.1%. Also, the last mentioned treatment achieved a high price for farmers by about 5.1% and total revenue of about 3.2% during the study period. Nowadays, Egypt has become the largest exporter of oranges in the world within the last year and the achieved earnings reached $661 million in 2019/2020. In addition, results showed that evaluation of using a treatment to reduce the rate of Washington navel orange cracking was economical to be applied.

基于化学计量学鉴定不同甜橙精油挥发性成分

采用感官定量描述分析、气相色谱-离子迁移谱(gas chromatography-ion mobility spectrometry,GC-IMS)及快速气相电子鼻并结合化学计量学,对采用冷压(cold pressing,CP)、微波辅助水蒸气蒸馏(microwaveassisted hydrodistillation,MAHD)和旋转锥蒸馏塔(spinning cone column,SCC)法提取的甜橙(血橙和脐橙为代表)精油进行挥发性成分差异分析。结果表明:3种方式提取的甜橙精油风味组成存在明显差异,CP提取精油喜爱度最高且具有更强的果香、甜香和花香,MAHD精油具有更强的脂香、青香和木香,而SCC萃取液香气浓度较低;GC-IMS共鉴定出64种挥发性化合物,主要为萜烯类、醇类和醛类,其次是酸类、酯类和其他化合物,指纹图谱结果显示,萜烯类在CP和MAHD精油中含量明显高于SCC萃取液,而醇类和醛类在MAHD精油和SCC萃取液中含量明显高于CP精油;基于相对气味活性值鉴定出β-月桂烯和芳樟醇是甜橙精油风味的主要贡献者;GC-IMS结合偏最小二乘法判别分析和变量投影重要性筛选出13种区分6种精油的标志性差异挥发性化合物;此外,快速气相电子鼻结合主成分分析和判别因子分析也能够成功区分6种甜橙精油挥发物差异。

赣南脐橙气候品质归一化指数构建

为建立赣南脐橙综合品质的气候评价方法,该研究基于2008—2011年和2021—2022年赣南脐橙单果质量、维生素C和固酸比等品质因子实测和气象资料,首先通过品质与气象要素的逐旬相关系数动态变化规律,找出关键气象要素及其影响时段;然后基于关键影响时段的气象要素,采用逐步回归法建立各品质因子的气象关系模型,并且结合“最大最小值”归一化法和加权求和法,模拟得到1981—2020年赣南脐橙综合品质指数(composite quality index,CQI);最后,基于综合品质指数与气象要素的相关性,构建赣南脐橙气候品质归一化指数(normalized climate-quality index,NCI)及其等级阈值。结果表明:各品质因子与光温要素相关性分为3个阶段,初夏(6月)和秋季(10—11月)光温充足有利于赣南脐橙品质提升,盛夏(7—8月)晴热高温对营养品质和风味不利;影响赣南脐橙综合品质指数(CQI)的关键气象要素为6月累积日照时数、7月上旬至9月中旬平均最高气温和9月下旬至10月下旬平均最高气温,基于以上要素构建的赣南脐橙气候品质归一化指数NCI≤0.45、0.45<NCI≤0.52、0.52<NCI≤0.65和NCI>0.65分别表示为差、较优、优和特优等级;利用2021—2022年宁都县和信丰县品质实测资料进行验证,NCI偏差多在0.07以内。该研究可为柑橘品质的敏感气象要素识别和气候品质评价研究提供一定参考。

脐橙采后草酸浸泡处理抑制指状青霉侵染的效应

为研究外源草酸诱导脐橙果实抗采后绿霉病的效应和抗氧化能力之间的关系,并筛选出外源草酸处理适宜浓度,以八九成成熟的“龙回红”脐橙果实为试验材料,分别使用0(清水对照)、12.5、25.0、50.0 mmol·L^(-1)草酸浸泡10 min后,在25℃环境中诱导抗性48 h,再刺伤接种指状青霉(Penicillium digitatum)孢子悬浮液,通过分析病斑直径筛选出外源草酸处理的最适浓度,并测定果实经最适浓度草酸处理和接种孢子悬浮液后黄皮层总酚和类黄酮含量、抗氧化酶活性和丙二醛(Malonaldehyde,MDA)含量及其动态变化。结果表明,12.5、25.0、50.0 mmol·L^(-1)草酸处理诱导脐橙抗绿霉病的效果分别为16.26%、25.22%和17.36%,25.0 mmol·L^(-1)的诱导效果显著高于其他浓度。25.0 mmol·L^(-1)草酸处理可以提高果实黄皮层抗坏血酸过氧化物酶、过氧化物酶和多酚氧化酶活性,增加总酚和类黄酮积累,提高自由基清除能力,抑制MDA积累,从而减轻脐橙绿霉病的发生。25.0 mmol·L^(-1)草酸处理提高脐橙对采后绿霉病的抗性,可能与其诱导提高了脐橙抗氧化能力密切相关。

土壤-植物系统中硒的生物有效性及其影响因素研究进展

硒的生物有效性是决定硒在土壤-植物系统中转运、积累的关键因素,然而目前关于该方面研究进展还缺乏系统的总结和论述。本文结合赣南富硒脐橙调查研究结果,以硒在土壤-植物系统中的运移为切入点,系统总结和论述了硒在土壤-植物系统中的氧化-还原、吸收、转运过程,探讨了土壤理化性质、微生物、施肥、农艺管理和植物生长阶段等对硒生物有效性和迁移的影响,并提出未来硒的研究热点:土壤微生物活性与硒生物地球化学循环的耦合关系;植物生长、果实品质与硒代谢相关的分子机制;结合同位素示踪技术和薄膜扩散梯度(DGT)技术原位探究硒在生物地球化学中的归趋。本综述可为土壤硒生物有效性调控、植物体系中硒的有效积累和农艺生物强化富硒措施方面的研究提供理论参考。

不同品种脐橙根际土丛枝菌根真菌群落多样性分析

以赣南早脐橙、红肉脐橙和纽荷尔脐橙3个品种脐橙的根际土壤为研究对象,研究不同品种脐橙根际土壤中丛枝菌根真菌(Arbuscular mycorrhizal fungi,AM真菌)群落特征。结果表明:脐橙品种显著影响根际土壤中AM真菌群落α多样性,纽荷尔脐橙根际土壤中的OTU数和ACE指数均显著低于赣南早脐橙和红肉脐橙(P<0.05);在各个菌属中,赣南早脐橙根际土壤中类球囊霉(Paraglomus)的相对丰度显著高于红肉脐橙和纽荷尔脐橙(P<0.05)。冗余分析(RDA)表明,土壤因子中,碱解氮显著影响脐橙根际土壤中AM真菌群落α多样性(F=7.8,P=0.034),速效钾显著影响脐橙根际土壤中AM真菌群落结构(F=2.7,P=0.008)。