Frontiers of Agriculture in China

ISSN 1673-7334

ISSN 1673-744X(Online)

CN 11-5729/S

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Genetic diversity studies of coarse and fine rice using RAPD markers
Saeed ARSHAD, Ahsan IQBAL, Sehar NAWAZ, Nisar AHMED
Front Agric Chin. 2011, 5 (2): 129-134.

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The availability of a genetically diverse gene pool is vitally important in varietal development. Molecular markers are being extensively utilized to explore the genetic diversity among native and exotic germplasm. This study was designed to reveal the genetic diversity and patterns of relationships among the 20 accessions/genotypes representative of basmati and non-basmati rice from the existing rice gene pool using RAPD markers. Employing RAPD, 17 decamer oligonucleotide primers directed the amplification of 116 fragments, out of which 101 were polymorphic (87.06%) while 15 fragments were monomorphic (12.93%). Similarity coefficients had ranged from 0.47 to 0.90. The average genetic similarity was calculated 0.68 (68%). In this study, the coarse rice genotypes showed more polymorphism (85.84%) than the fine rice genotypes (61.76%). Genotypes were clustered into 8 distinct groups: A, B, C, D, E, F, G, and H but two genotypes, i.e., Shadab and Kangni-27 showed divergence from all the genotypes of the groups. Therefore, these diverse genotypes may be included in future breeding programmes.

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Assessment of the combining ability and authentication of F1 hybrids using SSR markers in wheat (Triticum aestivum L.)
Muhammad Shahzad AHMED, Ihsan KHALIQ, Jehanzeb FAROOQ, Shahid Iqbal AWAN, Nisar AHMED, Faisal Saeed AWAN
Front Agric Chin. 2011, 5 (2): 135-140.

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Six wheat genotypes (three female and three male) were crossed for the study of some quantitative traits in wheat. Analysis of variance showed a highly significant difference for all the characters except flag leaf area, which was significant. Testers revealed that LU26S was the best general combiner only for plant height. Mehraj showed a good general combining ability effect on plant height, flag leaf area, peduncle length, and 1000-grain weight. Farid 2006 was the best male parent as general combiner for plant height, peduncle length, spike length, number of grains per spike, and grain yield per plant. The wheat parental lines revealed that 9381 was the best general combiner for plant height, flag leaf area, peduncle length, 1000-grain weight, and grain yield per plant. Whereas 9428 was the best general combiner for flag leaf area, spike length, and number of spikelets per spike. Among crosses, LU26S × 9272, LU26S × 9381, Mehraj × 9272, and Mehraj × 9381 showed a significant effect of specific combining ability (SCA) on grain yield per plant. Other crosses with significant and positive SCA effects were LU26S × 9272 on plant height and 1000-grain weight grain yield per plant, LU26S × 9428 on peduncle length, and Mehraj × 9381 on plant height and grain yield per plant. These crosses with significant effects of general combining ability (GCA) on grain yield per plant can be used in the development of new varieties. These crosses with nonadditive genes would give transgressive segregants. For yield improvement, vigilant selection of the potent transgressive segregants through family selection would be valuable for yield enhancement. A total of 15 SSR primers of Xgwm series and 5 of X series were used to find out the codominant loci in the hybrid and single dominant loci in parents. Out of 15 primers only, Xgwm-314 gave the polymorphic banding pattern. This primer showed the polymorphic dominant loci in the parents (LU26S, Mehraj, 9272 and 9381) and codominant loci midway between these parents. Therefore, this SSR primer was used to confirm the two best performing hybrids (LU26S × 9272 and Mehraj × 9381) on the bases of positively significant effects of GCA and SCA on plant height, 1000-grain weight and grain yield per plant, and other economically important traits. The two hybrids namely LU26S × 9272 and Mehraj × 9381 can be used in the further breeding program for the development of high yielding varieties.

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Comparative studies on some yield contributing traits of wheat sown in binary mixtures
Sabina ASGHAR, Muhammad KASHIF, Abdus Salam KHAN, Ihsan KHALIQ, Jehanzeb FAROOQ
Front Agric Chin. 2011, 5 (2): 141-145.

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Cultivar mixtures have been suggested as ways to increase crop productivity. This field study was conducted to investigate the competition among five cultivated varieties of wheat (Triticum aestivum L.) for the traits like plant height, flag leaf area, fertile tillers per plant, spike length, spikelets per spike, spike density, grain weight per spike, and seed index in relation to competition with yield per plant. It was observed that cultivar mixtures ought to be more productive than corresponding pure stands. Four binary combinations of Seher2006-Kohistan97, Farid2006-SH2002, SH2002-Shahkar95, and SH2002-Kohistan97 were superior in performance, showing land equivalent ratio (LER) values greater than one for plant height, fertile tillers per plant, spike density, grain weight per spike, and grain yield per plant. It was observed that the performance of binary mixtures was mainly due to the increased average performance in spike density, grain weight per spike, and grain yield per plant. The competitive ability of wheat varieties in mixtures was independent of each other for the respective traits, which lead to cumulative effects for the increased performance within the associates in mixtures.

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A proteomic approach to investigating the promotive effects of brassinolide on root growth of rice seedlings
Shenghui LI, Fengru WANG, Jingao DONG
Front Agric Chin. 2011, 5 (2): 146-151.

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Brassinolide influenced rice (Oryza sativa L.) root growth in a concentration-dependent manner. Roots grown in 0.1 nmol/L BL were 28% longer than those in the control. On the other hand, the roots grown in 1000 nmol/L BL were 65% shorter in comparison with those in the control. To investigate how BL influences rice root growth, proteome analysis techniques were applied. After BL treatments, total proteins from rice root were extracted separately. Extracted proteins were separated by two-dimensional polyacrylamide gel electrophoresis and analyzed using an automated protein sequencer and mass spectrometer. There were 33 proteins that showed differences in the accumulation levels as a result of treatments with BL. Proteins related to stress tolerance, enzymes, and cell structure were mainly found in the root. There were many proteins regulated by other hormone or light also. Results suggest that the physiologic functions of these proteins detected using powerful proteome analysis are implicated in root elongation triggered by BL. High-level brassinosteriod (BR) indicated that IAA amidohydrolase, which can release active IAA from IAA pool was increased, and the IAA level was so high that the root length was inhibited.

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Identification of QTLs for biomass production in maize (Zea mays L.) under different phosphorus levels at two sites
Junyi CHEN, Yilin CAI, Li XU, Jiuguang WANG, Wenlong ZHANG, Guoqiang WANG, Delin XU, Tianqing CHEN, Xuegao LU, Haiyan SUN, Aiying HUANG, Ying LIANG, Guoli DAI, Hongni QIN, Zuchun HUANG, Zhaojing ZHU, Zhiguo YANG, Jun XU, Shoufeng KUANG
Front Agric Chin. 2011, 5 (2): 152-161.

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The biomass production (BP), the leaf age (LA), and the plant height (PH) as well as the quantitative trait loci (QTLs) associated with these traits were determined for F2:3 population derived from the cross of two contrasting maize (Zea mays L.) genotypes: 082 and Ye107. By using composite interval mapping, a total of 12 and 12 distinct QTLs were identified at Kaixian and Southwest University under deficient phosphorus. Another 9 and 8 distinct QTLs were identified at two sites under normal phosphorus, respectively. Seven coincident QTLs for two traits (BP and LA) were detected in the interval bnlg1832-P2M8/j (bin 1.05) on Chromosome 1, and four consistent QTLs for one trait (PH) were coincident in the interval umc1102-P1M7/d (bin 3.05) on Chromosome 3. These coincident QTLs in two important genomic regions were identified under different phosphorus levels and two different environments. Therefore, the above two segments one (bnlg1832-P2M8/j) identified in Chromosome 1 and the other (umc1102-P1M7/d) identified in Chromosome 3 may be used in future for marker-assisted selection and high-resolution mapping leading to map-based cloning of QTLs for agronomically important traits under phosphorus deficiency.

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The molecular characterization and function of miRNAs on mediation of target gene silencing in plants
Chengjin GUO, Juntao GU, Xiaojuan LI, Wenjing LU, Chunying MA, Kai XIAO
Front Agric Chin. 2011, 5 (2): 162-172.

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MiRNAs belong to one type of noncoding RNAs involved in developmental regulation, genome maintenance, and defense in eukaryotes. In plants, the miRNAs are involved in many molecular interactions, including interfere with expression of mRNAs encoding factors that control developmental processes, stem cell maintenances, auxin responses, and other developmental and physiologic processes. In this paper, the molecular characterization and the functions of miRNAs on mediation of target gene silencing in plants have been overviewed. Further studies on the miRNAs will be helpful for elucidation of the molecular mechanism of post- transcriptional gene silencing in plants.

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Comparative karyotypic analysis of A and C genomes in the genus Oryza with C0t-1 DNA and RFLP
Junbo ZHOU, Weizhen LAN, Rui QIN
Front Agric Chin. 2011, 5 (2): 173-180.

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Fluorescence in situ hybridization (FISH) was applied to somatic chromosomes preparations of Oryza sativa L. (AA), O. glaberrima (AA), and O. officinalis Wall. (CC) with a labeled probe of C0t-1 DNA. Genomic in situ hybridization to its own chromosomes (self-GISH) was conducted in a control experiment. The homologous chromosomes showed similar signal bands probed by C0t-1 DNA, while karyotypic analysis of chromosomes between A genome in the two cultivated species and C genome in O. officinalis were conducted based on the band patterns. The ideograms with C0t-1 DNA signal bands were also built. The nonuniform distribution of hybridization signals of C0t-1 DNA from O. sativa and that on its own chromosome of O. officinalis were observed. However, the similarity and correspondence between C0t-1 DNA signal patterns and genomic DNA signal patterns indicated that the self-GISH signals actually resulted from the hybridization of genomic repetitive sequences to the chromosomes. The restriction fragment length polymorphism (RFLP) marker, R2676, from the chromosome 8 of O. sativa and O. officinalis, was used as a probe to somatic hybrid on chromosomes for comparative karyotypic analysis between O. glaberrima and O. officinalis. The results showed that R2676 was located on the short arm of chromosome 7 in O. officinalis and chromosome 4 in O. glaberrima. The percentage distances from the centromere to hybridization sites were 91.56±5.62 and 86.20±3.17. Our results revealed that the relative length of O. officinalis chromosome 8 does not follow conventional chromosome length in descending order of number. C0t-1 DNA of A genome signals were detected in the end of the short arm of O. officinalis chromosome 8, indicating that the highly and moderately repetitive DNA sequences in this region were considerably similar between C and A genomes. However, the fluorescence intensity on the chromosomes of C0t-1 DNA of A genome was less than that of its own C genome from O. officinalis, which would be one of the causes for the fact that highly and moderately repetitive DNA sequences were amplified in O. officinalis. No homology signal of C0t-1 DNA from O. sativa was detected in the end of the long arm of O. glaberrima, indicating that repetitive DNA sequences of A genome in two cultivated rice were lost in the evolutional history. In this paper, using comparative karyotypic analysis of RFLP combined C0t-1 DNA signal bands, the evolutionary mechanism of genome in genus Oryza was also discussed.

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Knockdown of ACS9 expression in Arabidopsis decreases the tolerance to salt and osmotic stress
Xueli HAN, Yonggang PAN, Yingchao LIU, Jihong XING, Jingao DONG
Front Agric Chin. 2011, 5 (2): 181-186.

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Based on the DNA sequence of ACS9, two produced fragments were subcloned into binary vector pCAMBIA1300 in antisense and sense orientations, and the generated RNA interference (RNAi) vector was then transformed into Arabidopsis thaliana. The stress resistance function of ACS9 gene in Arabidopsis thaliana was researched by determination of stress resistance physiologic indexes, NaCl and PEG6000 resistance. The results showed that the inhibition of ACS9 expression enhanced the sensitivity to high concentration NaCl (150 mmol/L) and PEG6000(7%) in Arabidopsis thaliana seeding stage. The proline contents and water loss rates in transgenic plants were 0.68 and 1.4 times higher than those in the wild-type leaves, respectively, indicating that the inhibition of ACS9 expression due to salt and drought resistant was reduced and suggested that ACS9 gene played important roles in plant salt and drought tolerance.

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Plant mitogen-activated protein kinases and their roles in mediation of signal transduction in abiotic stresses
Ruijuan LI, Chengjin GUO, Xiaojuan LI, Juntao GU, Wenjing LU, Kai XIAO
Front Agric Chin. 2011, 5 (2): 187-195.

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Mitogen-activated protein kinase (MAPK) cascade plays a central role in transfer information from diverse receptors/sensors to a wide range of cellular responses in plants. MAP kinases are organized into a complex network for efficient transmission of specific stimuli, including the abiotic stress signaling. In recent years, the mutants of loss-of-function and gain-of-function, and other additional tools are used to investigate the plant MAPK cascades. This review has summarized the recent progress on the MAPK cascade involved in mediation of the transduction of several pronounced abiotic stress signalings, such as salt, drought, low and high temperature, wound, hormone, and deficient nutrients. Currently, although part of the components of the MAPK cascade responding to the abiotic stresses have been identified, the integral molecular mechanisms of the abiotic stresses signaling transduction mediated via MAPK cascade are largely unknown and need to be elucidated further in the future.

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Cloning of endo-β-glucanase I gene and expression in Pichia pastoris
Yu BAI, Runfang GUO, Hongwei YU, Long JIAO, Shuli DING, Yingmin JIA
Front Agric Chin. 2011, 5 (2): 196-200.

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Total RNA of Thermoascus aurantiacus was isolated from its mycelium and acted as template for RT-PCR. The full-length cDNA encoding an endo-β-glucanase I was cloned via RACE-PCR method and the cDNA contained an ORF of 1005 bp encoding 305 amino acids. A recombinant plasmid, pPIC9k-egI, was constructed by inserting the ORF sequence of endo-β-glucanase I gene (egI) into the yeast expression vector pPIC9k and transformed to Pichia pastoris GS115. The results showed that the recombinant endo-β-glucanase I was excreted into the fermentation medium. The highest activity of endo-β-glucanase I and the protein content were up to 45.42 U/mL and 788.26 μg/mL at incubation time of 144 h. The optimal temperature and pH for the recombinant endo-β-glucanase I were found to be 70oC and 3.5, respectively.

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Physiological and biochemical changes associated with flower development and senescence in Consolida ajacis Nieuwl cv. Violet blue
Front Agric Chin. 2011, 5 (2): 201-208.

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Flower development of Consolida ajacis cv. Violet blue growing in the Kashmir University Botanic Garden (KUBG) was divided into six stages (I–VI) from the tight bud stage to the senescent stage. The average life span of an individual flower after it is fully open is about 4 days. Membrane permeability of sepal tissues estimated as electrical conductivity of leachates increased during senescence. The content of sugars and soluble proteins in the sepal tissues increased during flower opening and declined thereafter during senescence. The α-amino acid content registered an increase as the flowers opened and senesced. The protease activity increased as the flower progressed toward senescence. Flower opening was closely correlated to the sugar status of sepals, while the increase in the protease activity was commensurate with the decrease in the tissue content of soluble protein levels. The results suggested that the reduction in sugar status and the elevation in protease activity are among the important changes associated with the sepal senescence of Consolida ajacis flowers. SDS-PAGE of protein extracts from sepal tissues suggested a general decrease in the expression of some high molecular weight proteins and an increase in low molecular weight proteins during the flower development and senescence. At this stage, it is not known whether these polypeptides play an important role in the senescence of C. ajacis flowers. Understanding the nature of these proteins can provide new insights into the pathways to execute the senescence and the post-transcriptional regulation of senescence in this flower system.

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Genomic organization and sequence polymorphism of a farnesyl diphosphate synthase gene in apples (Malus domestica Borkh.)
Kejun YUAN, Lixiang Huang, Chengxiang AI, Hairong WEI, Qingzhong LIU
Front Agric Chin. 2011, 5 (2): 209-214.

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Primer pairs were designed to amplify the genomic DNA sequence of the farnesyl diphosphate synthase (FPPS) gene by PCR. The PCR products were sequenced, spliced and compared to the cDNA sequence in the GenBank (accession No. AY083165). The genomic sequence and intron-exon organization of FPPS1 gene in the apple cultivar ‘Fuji’ were thus obtained. The FPPS1 genomic sequence has been registered in the GenBank (accession No. HM545312). It has 11 introns and 12 exons. The sizes of 11 introns were 559 bp, 108 bp, 144 bp, 114 bp, 84 bp, 690 bp, 373 bp, 168 bp, 87 bp, 91 bp and 97bp, and their phases were 0, 1, 0, 0, 0, 2, 0, 0, 0, 0 and 0, respectively. The sizes of 12 exons were 111 bp, 25 bp, 116 bp, 87 bp, 117bp, 89 bp, 52 bp, 96 bp, 45 bp, 90 bp, 72 bp and>12 bp, respectively. Gene sequence comparison results of five apple cultivars indicated that the development of apple superficial scald was not influenced by the mutations in the exon sequence of FPPS1 gene. A 6-bp repeat unit deletion mutation and many SNP mutations in the introns, mainly in the introns of one allele, were identified in the apple scald-resistant cultivar ‘Golden Delicious’. This is the first report on the genomic organization and coding region polymorphism of FPPS gene in apples and other fruit trees.

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Generation and identification of four new monosomic addition lines of flowering Chinese cabbage-Chinese kale
Erqiao SHEN, Xiaofeng LI, Chenghe ZHANG, Xine WANG, Shuxin XUAN
Front Agric Chin. 2011, 5 (2): 215-220.

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A selection test of four new flowering Chinese cabbage (Brassica campestris L. var. utilis Tsen et Lee)-Chinese kale (Brassica alboglabra Bailey) monosomic alien addition lines was conducted by karyotype analysis and morphological marker identification. The results mainly showed the following: 61‘2n + 1’ plants screened out from 655 progeny plants of the trigenomic hybrid (AAC) backcrossed with its parent flowering Chinese cabbage (AA), four new monosomic alien addition lines(AA+ C1, AA+ C5, AA+ C8 and AA+ C9) obtained from the 61 ‘2n + 1’ plants, the transmission rates of the monosomic alien addition lines (AA+ C1, AA+ C5 and AA+ C8) of 19.7%, 23.44%, and 36.51% by female gametes and 7.84%, 8.89%, and 9.43% by male gametes, respectively, and the alien chromosome C-1 and C-5 had partial homology with at least one chromosome of A-genome.

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Comparison of the methods of RNA isolation from Juglans regia L. buds
Fuqiang HE, Hongxia WANG, Xiaobo SONG, Zhihua ZHANG
Front Agric Chin. 2011, 5 (2): 221-224.

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In this paper, four RNA extraction methods (CTAB method, TRIzol method, D326A reagent and RP3301 Kit) for walnut buds were compared by agarose gel electrophoresis and spectrophotometry, and the optimal method was verified further by Reverse transcription and PCR amplification (RT-PCR). There was a certain degree of degradation for the extracted RNA by CTAB method, TRIzol method and D326A reagent. Moreover, protein was found in the CTAB method. For the three unsatisfactory methods, longer operation time could be the main reason that RNA could not be separated in time with polyphenols, polysaccharides and other secondary metabolites. RP3301 kit was suitable for the RNA extraction from walnut buds with high purity, simplicity, innocuity and no degradation. This research will provide a fundamental basis for the cloning and expression analysis of genes and other follow-up tests.

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N-catch crops affect soil profile nitrate-N accumulation during vegetable cultivation
Yanzhi JI, Xiaotang JU, Wanzhong FENG, Lijuan ZHANG, Shuqing LIU
Front Agric Chin. 2011, 5 (2): 225-230.

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To reduce nitrate leaching, the effects of three N-catch crops of sweet corn (Zea mays L.), amaranth (Amaranthus spp.), and sweet sorghum (SorghumLinn.) on nitrate-N accumulation in the soil profile were examined using an incubation experiment. Results showed that the biomass and N absorbed by sweet corn were the largest compared with the other two N-catch crop treatments. Root length density for sweet corn, amaranth, and sweet sorghum in the 0–150 cm soil layer was 0.66, 0.34 and 0.46 cm/cm3, respectively, and root dry weight was 0.065, 0.021 and 0.038 mg/cm3, respectively. In the 0–200 cm soil layer, nitrate-N accumulation for fallow, mature sweet sorghum, amaranth, and sweet corn was 1124.7, 899.4, 867.4 and 794.2 kg/hm2, respectively, where the treatment of sweet corn had the smallest N-accumulation. The nitrate-N leachability of fallow, sweet corn, amaranth, and sweet sorghum treatment was 3.6, 1.9, 2.4 and 2.6 kg/hm2, respectively, indicating that cropping of sweet corn, amaranth, and sweet sorghum could reduce the leachability by 47%, 35% and 28% in comparison with fallow treatment. Therefore, the cultivation of N-catch crops can reduce nitrate leaching in seasonal soil, and the sweet corn might be the most suitable catch crop.

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Impacts of abiotic factors on population fluctuation of insect fauna of Vigna radiata and Tetranychus urticae Koch in Sindh, Pakistan
Yasir Ahmed KHAN, Wajad NAZEER, Asifa HAMEED, Jehanzeb FAROOQ, Muhammad Rafiq SHAHID
Front Agric Chin. 2011, 5 (2): 231-236.

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Effect of temperature and relative humidity on population dynamics of insect pests of mung bean was studied during mung bean growing season of 2005. Insect pests included thrips (Thrips tabaci Lind.) and field cricket (Gryllus assimilis) and one arachnid pest mite (Tetranychus urticae Koch). Results revealed that the maximum population of thrips and mites was observed on August 23, 2005 with 1.537±0.031 per leaf and July 6, 2005 with 3.271±0.09 per leaf, respectively. The population of field cricket differed significantly during crop season and reached its peak during the initial stage of crop growth on June 14, 2005, i.e., 0.873±0.014 per plant at the temperature and relative humidity of 32°C and 54%, respectively, while the minimum population was noted on August, i.e., 0.710±0.010 per plant. Present studies conclusively document the correlation of weather factors and insect pest population. Temperature had a negative and significant correlation with thrips (r=-0.860) and a positive and significant correlation with mites (r=0.606) and field cricket (r=0.439). However, the relative humidity displayed a positive and significant correlation with thrips (r=0.569), a negative non-significant correlation with mites (r=-0.313), and a significant negative correlation with field cricket (r=-0.770).

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Additive insect-resistant effects of transgenic triploid Chinese white poplar against Clostera anachoreta
Shengliang YUAN, Minsheng YANG, Baojia GAO
Front Agric Chin. 2011, 5 (2): 237-240.

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Two generations of Clostera anachoreta (Fabricius) larvae were fed continuously with leaves of selected clones of transgenic (Bt+ API) triploid Chinese white poplar in order to evaluate additive insect-resistant effects of transgenic triploid Chinese white poplar. When the two generations were subcultured with the high and medium level insect-resistant transgenic poplar, the high and medium level insect-resistant transgenic poplar manifested its obvious additive resistance to C. anachoreta (Fabricius), with higher mortality of the second generation C. anachoreta (Fabricius) larvae and longer larvae growth period of the second generation than those of the first generation. Furthermore, the weight of pupa and the fecundity of the second generation were lower than those of the first generation. However, there was no significant difference between both generations when subcultured with low level insect-resistant transgenic poplar. These results implied that the population of C. anachoreta (Fabricius) would decline gradually to under the economic threshold even when planting the medium level insect-resistant transgenic poplars in the environment.

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Seed germination techniques of Phoenix dactylifera: A new experience from Bangladesh
Md. Salim AZAD, Md. Tabiur RAHMAN, Md. Abdul MATIN
Front Agric Chin. 2011, 5 (2): 241-246.

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A new experiment on seed germination technique for Phoenix dactylifera, an exotic species was conducted in the nursery of Forestry and Wood Technology Discipline, Khulna University, Bangladesh. The seeds imported from Saudi Arabia were collected from Nirala Central Mosque, Khulna, Bangladesh, in September 2008 and treated with four presowing treatments (control, immersion in normal water at room temperature (20–22°C) for 12 h, immersion in sun-heated water (25–35°C) for 12 h, and immersion in hot water (50°C) for 10 h) before seed germination with different germination media (well dried loamy soil, coarse sand, mixture of coarse and fine sand at a ratio of 3:1, mixture of coarse and fine sand at a ratio of 3:2, and mixture of coarse and fine sand at a ratio of 1:1). The experiment showed that presowing treatments significantly increased the germination rates of seeds compared to those in control (68%) and hot water treatment (69%). The highest germination success (84%) was found in the immersion in normal water and sun-heated water for 12 h. Experiment also showed that seed germination with course sand and mixture of coarse and fine sand with a ratio of 3:1 performed better than the loamy soil. Germination started from 21 to 26 days and completed between 38–40 days of the germination period in all treatments. ANOVA showed a significant difference among the treatments in seed germination, but there was no significant difference among the media in seed germination. Normal water and sun-heated water for 12 h for pretreatment and coarse sand or mixture of coarse and fine sand at a ratio of 3:1 may be recommended for seed germination of the species in rural Bangladesh.

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Effects of harvesting time on fruit quality and internal browning of ‘Wonhuwang’ pear during cold storage
Limei LI, Junfeng GUAN, Jingang HE
Front Agric Chin. 2011, 5 (2): 247-250.

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Average fruit weight, seed browning, flesh firmness, total soluble solids, internal browning, and skin blackening were used to determine the optimum harvesting time of ‘Wonhuwang’ pear. Pears for storage were picked three times at 5-day intervals before, during, and after estimated optimum harvesting date. Average fruit weight and seed browning degree were calculated at each picking time. Quality changes, internal browning, and skin blackening were employed to estimate the optimum harvest date. It was found that fruit quality parameters both at harvest and after storage depended on the stage of ripeness at which the pears were picked. Pears harvested earliest (H1) had the highest firmness both before and after storage and lost less percentage of their firmness during storage. The latest picked pears (H3) showed higher total soluble solids value and serious internal browning and skin blackening due to their over ripeness. Pears picked on the 15th of August (H2) had higher firmness and total soluble solids, lower extent of internal browning, and no skin blackening. Based on the changes in fruit firmness and physiologic disorder during ripening and storage, the optimal harvesting time for ‘Wonhuwang’ pear in Shijiazhuang area is around the 15th of August.

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