Dec 2007, Volume 1 Issue 4

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  • Yeshi A. Wamishe, JIA Yulin, Pratibha Singh, Richard D. Cartwright
    The rates of in vitro hyphal growth of Rhizoctonia solani isolates, and their pathogenicity were evaluated to identify R. solani isolates that are suitable to detect quantitative resistance in rice. The isolates of R. solani were purified from the infected rice and two grass species in Arkansas over three years. Among 200 Rhizoctonia-like isolates, 102 isolates were identified as R. solani, and confirmed using a ribosomal DNA internal transcribed spacers  marker. The rates of in vitro hyphal growth of the 102 R. solani isolates ranged from 1.17 to 1.89 mm/h, of which only 13.7% were significantly different from each other. The rates of in vitro hyphal growth of eight selected isolates were correlated with lesion lengths (r = 0.86 at P = 0.005 9 and r = 0.93 at P = 0.000 1) on the detached leaves of rice cultivars of Jasmine 85 (resistant) and M202 (susceptible), respectively. The eight isolates were selected based on the mean values of the maximal (1.89), median (1.54) and minimal (1.17) rates of hyphal growth. Two isolates that consistently exhibited significant differences in the rates of the hyphal growth were selected to examine the aggressiveness of isolates in micro-chambers. Using a micro-chamber, the slow growing isolates separated susceptible cultivars from moderately resistant cultivars better than the fast growing isolates. In contrast, the differences in disease reactions between both R. solani isolates were undetected using a standard field evaluation method. We suggest that the slow growing isolates are more useful than the fast growing isolates for detecting quantitative resistance with the micro-chamber method.
  • FAN Yongshan, MA Jifang, GUI Xiumei, AN Xinlong, SUN Shuqin, DONG Jingao
    Mature ascocarps and ascospores in the heterothallic ascomycete fungus, Setosphaeria turcica, were successfully produced in Sach s medium with barley culm as the mating stimulator after four weeks  coincubation of two opposite mating type isolates at 25°C in darkness. A single isolate could not produce ascospores or ascocarps. The ascocarps were produced on the exposed surface and embedded parts of barley culm or in the upper layer of the medium. The asci linked themselves to ascocarp with their short handles and assembled at the bottom of the ascocarp. Many asci had four to six colorless mature ascospores with one to six septa. But asci with eight ascospores were also found. Using isolate 9914 and isolate 9961 as standard testers for mating types (MAT1 and MAT2), respectively, 94 isolates of S. turcica collected from northern China in 1999, 2003, and 2004 were grouped into three mating types: MAT1 (53 isolates), MAT2 (31 isolates) and MAT12 (10 isolates). The MAT12 isolates, which were first found in China, were compatible with not only MAT1 isolates but also MAT2 isolates. No MAT12 isolates were found in 1999, but 2 MAT12 isolates and 8 MAT12 isolates were found in 2001 and 2003, respectively. The geographic distribution of different mating types was unequal among locations. Generally the frequency of MAT1 was significantly higher than that of MAT2 and MAT12. The unequal distribution of mating types suggested a low fre quency of genetic recombination. The pathogenicity of different mating type isolates was tested on the susceptible corn inbred B37 and the results revealed that the disease latency period, disease incidence, lesion area and conidia production were not significantly different among the three mating type groups. However, the pathogenicity of the progeny isolates of isolate 99-12 (MAT2, race 1) and isolate 99-15 (MAT1, race 0) was significantly different from the parent isolates, isolate 99-12 and isolate 99-15, suggesting that sexual recombination could cause significantly virulence variation in S. turcica. Random amplification of polymorphic DNA (RAPD) analysis also revealed high genotype diversity among the progeny isolates, indicating that the sexual recombination could also produce significant genetic variation in the fungal pathogen.
  • LI Zhijun, LONG Weiping, ZHENG Jinrong, LEI Jianjun
    Five isolates collected from different pepper-cropping regions in Guangdong Province, China were determined. Based on their morphological characteristics and symptoms after being re-inoculated to pepper, these isolates were identified as Phytophythora capsici Leonian. The sporangia induced on carrot medium (CA) were morphologically similar and most of their shapes were ovate or elliptic, and obviously papillate. The mean size of the sporangium was 40.8–45.9 (l) μm×23.2–30.9 (b) μm, with l/b ratio 1.4–1.8. There were evident differences in mycelial growth rate, productivity of sporangia and pathogenicity to pepper among the isolates. A test of physiological characteristics showed that one isolate was determined as Race 1, and the other four isolates belonged to Race 3. It is concluded that Race 3 is most likely to be the predominent race in Guangdong Province, China.
  • ZHOU Guisheng, FENG Chaonian, ZHOU Qing
    This research was to investigate physiological activities and the expression of insecticidal protein in cotton leaves of Kemian 1, a widely grown cotton cultivar in the lower reaches of the Yangtze River, treated under high (40°C and 35°C) and low (25°C and 20°C) temperatures for 48 h. The main results indicated that the contents of free amino acid and malondialdehyde (MDA) increased during the heat and cold stress with the biggest increments in the first 12 h; and the content of soluble protein, activities of superoxide dismutase (SOD), and glutamic-pyruvic transaminase (GPT) decreased during the stress with the biggest decrements also in the first 12 h; the activity of nitrate reductase (NR) decreased in the first 24 h, and during the remaining 24 h its activity followed a gradual uptrend. The content of insecticidal protein in cotton leaves followed a downtrend during the stress, and the biggest decrements occurred in the first 12 h, suggesting that the expression of insecticidal protein was immediately inhibited during the process of stress. The results also indicated that physiological activities and the expression of insecticidal protein in cotton leaves were closely related. Compared with other stress temperatures, 40°C produced more immediate effects on the physiological activities and insecticidal protein content. In contrast to the peak flowering period, the physiological activities and insecticidal protein expression at the peak boll-setting period were more susceptible to heat and cold stress.
  • ZHU Lihong
    Views and comments concerning rice high-yielding breeding in China had been touched upon: (1) historical development of rice breeding in China and its prominent contributions recounted; current challenges evolved from rapid population increase, erosion of key natural resources and socioeconomic changes envisaged; (2) concept of extra or super high-yielding rice breeding and related ideas embraced nowadays in the main rice-producing countries assessed; the conception of so-called superrice in China could have been misled and misunderstood, and no substantial genetical differences could be affirmed yet between superrice and modern high-yielding rice; (3) two strategical approaches of rice production and breeding in China would have been persistent in the construction of most favorable-to-growth rice fields to plant rice varieties with high-yielding potentiality as well as renovation and rejuvenation of less favorable rice fields to plant most adaptableto-ecoenvironment varieties with promising productivity; in addition, breeding for rice varieties compatible with the specific rice regions ridden by adverse ecoenvironments; (4) overview of the relationship between the development of genetical researches and the perspective of rice breeding; integration of the classical genetical principles and breeding methods and techniques wherefrom with molecular biotechniques underscored. Finally, appeal to the breeders to adhere to due attentions to the development of genetics and promote pragmatism and traditional ethic solemnly so as to live up to implementing the national rice breeding mandates.
  • WANG Jiaojiao, GUO Li, XIAO Kai
    Under abiotic stress, the calcium-dependent protein kinases (CDPKs) in plant species are activated by the fluctuated Ca2+ levels in cytoplasm and thereby provide a mechanism to decode calcium signals. In this paper, twenty-two rice CDPK genes were identified based on scanning the rice genome released in National Center for Biotechnology Information (NCBI). It was found that there were dramatic differences on the DNA length, cDNA length, open reading frame (ORF) and the translated amino acids among the rice CDPK genes, with the highest diversity on the DNA length. Calculations of the exon/intron numbers and the lengths of exon and intron revealed that all of the rice CDPK genes had the longest exon at the position of exon 1, but the lengths of introns in different genes showed different patterns. The gene structure and phylogenetic analysis indicated that the rice CDPK genes had derived at least from two diffe rent ancestors during the evolution. The expression analysis elucidated that the rice CDPK genes showed different patterns under normal growth (CK) and salt stress condition, including constitutively expression (OsCDPK4, OsCDPK18, OsCDPK19 and OsCDPK24), down- or up-regulated in roots by salt stress (OsCDPK10 and OsCDPK16), up-regulated in leaves by salt stress (OsCDPK6, OsCDPK20 and OsCDPK13), and no detected transcripts under CK and salt stress con dition. Therefore, the members of rice CDPK gene family should be evolutionally divergent and several members could play an important role in transducing the signal of salt stress.
  • YANG Lanfang, CAI Zucong, QI Shihua
    As a safe, stable and practical labeling method, the natural abundance of 13C has been widely used in a carbon cycle in the soil-plant system. In order to understand the effects of maize growth and photosynthesis on the value of δ13C in soil respiration, the value of δ13C in soil respiration was determined by mass spectrum after being trapped in a NaOH solution under a closed static chamber and then turned into barium carbonate in a pot experiment. The results showed that maize growth and photosynthesis significantly affected the value of δ13C in the soil respiration. In maize-planted soil, the value of δ13C in soil respiration had a clear seasonal variation. It changed with maize growth in the range of –14.57‰ to –12.3‰ and decreased during the period of trumpeting>ripening>flowering stages. The difference of δ13C in soil respiration during various maize growth stages added up to about 2.3‰. However, in bare soil, δ13C in soil respiration ranged from –19.34‰ to –19.13‰ and did not change significantly over time. The δ13C in soil respiration in the maize-planted soil was the lowest at flowering stage. This was mainly due to the decline of the input in assimilates into soil and the decrease in root activity. However, the δ13C increased at ripening stage, due to the decomposition and ingestion of senescent and died roots by soil microorganisms. In the planted soil, δ13C in soil respiration was significantly higher during daytime than at nighttime at flowering and ripening stages. The difference of δ13C in soil respiration between day and night periods added up to about 1.4‰ and 2.1‰ at flowering and ripening stages, respectively. Shading maize plants at the trumpeting stage decreased the value of δ13C in soil respiration significantly. The difference of δ13C in soil respiration between the treatment of non-shading and shading plants added up to 2.85‰. It was concluded that δ13C in soil respiration was remarkably controlled by the maize growth and photosynthesis in planted soil. Soil respiration was mainly derived from the recent assimilates during maize growth.
  • LI Xia, LI Lianlu, WANG Meiyun, DING Zaisong, ZHAO Ming
    Four maize inbred lines with different photosynthetic rates and their two hybrids were used as test materials, and the diurnal variations of their photosynthesis parameters in the silking stage were measured to study the heterosis of photosynthetic performance. Results showed that net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) all presented an obvious single-peaked curve in a day, with the peak values occurring at 10:00–12:00, 12:00, 10:00–12:00 a.m., respectively, while water use efficiency (WUE) had a V  type variant trend, with the lowest value appearing at 12:00. The diurnal variation of Pn and Tr was correlated markedly with Gs, suggesting that Gs played an important role in regulating the diurnal variation of Pn and Tr, and Pn, Tr and Gs had a higher heterosis in the afternoon than in the morning, while the WUE was in reverse, indicating that maize hybrid had higher resistance to the high temperature and dehydration in the afternoon, which provided a new path to select varieties with a high net photosynthetic rate.
  • LIU Xiaojing, LIU Hui, ZHAO Ping, SUN Guchou, LIN Yongbiao, RAO Xingquan, WANG Yuesi
    With closed static chamber and modified gas chromatograph (HP5890II), the in situ measurements were made on the CO2, CH4 and N2O emissions from winter-fallowed paddy fields in the hilly areas of South China. Gas samples were taken simultaneously from the fields with and without rice stubble. The results showed that both of the fields had the peak value of CO2 flux in the later afternoon. In the fields with and without rice stubble, the CH4 flux was positive in the day time while negative in the night, and the N2O flux in the day time was 1.79 and 1.58 times as much as that in the night, respectively. The diurnal average CO2 flux in the plot with rice residue was significantly higher than that of bare plot (P<0.05). Correlation analysis demonstrated that CO2 flux in the winter-fallowed paddy fields had significant correlations with soil temperature at a depth of 5 cm, aboveground temperature and air temperature, suggesting that temperature was the main factor affecting CO2 emission from rice fields after harvesting. During the observation time (from November 10, 2003 to January 18, 2004), the average CO2, CH4 and N2O fluxes in the field with rice residue were (180.69±21.21) mg/m2·h, (?0.04±0.01) and (21.26±19.31) μg/m2·h, respectively. Compared with bare fields, the CO2 flux in the field with rice residue was 13.06% higher, CH4 absorption increased by 50%, while N2O flux was 60.75% lower. It was concluded that the winter-fallowed paddy field in hilly areas of South China was the source of atmospheric CO2 and N2O, and the sink of atmospheric CH4.
  • TANG Guoyong, XIAO He′ai, SU Yirong, HUANG Daoyou, LIU Shoulong, HUANG Min, TONG Chengli, WU Jinshui
    The contents of soil organic C (SOC), total N (TN), total P (TP), dissolved N (DN), Olsen-P, and microbial biomass C, N, P (BC, BN, BP) of 254 paddy soils (0–18 cm in depth) in a hilly red soil region of subtropical zone of China were studied. The results showed that the contents of SOC, TN, BC, BN and DN of paddy soils at the bottom of hills were 14.6%, 13.6%, 24.6%, 20.4% and 95.8% higher than those at the foothill, respectively. The Olsen-P content of paddy soils at the foothill was 33.3% higher than that at the bottom of hills. However, the differences in TP, BP and available P (the sum of BP and Olsen-P) contents were not significant between the two positions. In addition, the ratios of soil C/P, BC/BP and BC/SOC of paddy soils at the bottom of hills were 12.7%, 28.5% and 8.2% higher than those at the foothill, respectively, but the differences in ratios of soil C/N, BC/BN, BN/TN and BP/TP were not statistically significant between various positions.
  • WANG Suping, JIA Yongxia, GUO Shirong, ZHOU Guoxian
    Seedlings from the salt-sensitive cucumber cultivar Jinchun No. 2 and the salt-tolerant cucumber cultivar Changchun Mici were exposed for 8 days to 50 mmol/L NaCl in the absence or in the presence of exogenous foliar spraying PAs [putrescine (Put), spermidine (Spd), and spermine (Spm) 1 mmol/L] to compare the effects of different kinds of polyamines (PAs) on plant tolerance to salinity. This paper studied the effects of exogenous PAs on K+, Na+ and Cl  in different organs of cucumber seedlings. The results showed that K+ content as well as the ratios of K/Na and Cl/Na decreased, while Na+ and Cl- concentrations increased in salt-treated cucumber seedlings. The differences in K+, Na+ and Cl- content and the K/Na and Cl/Na ratios were greater for the salt sensitive cultivar Jinchun No. 2 than for the salt-tolerant cultivar Changchun Mici. Cucumber seedlings treated with exogenous polyamines and combined with salinity exhibited a higher level of K+ accumulation and lower levels of Na+ and Cl- accumulation compared with the seedlings treated only with salt stress. Among the three kinds of polyamines, Spd and Spm were more effective in inhibiting the accumulation of Na+ and reduction of K+. However, Put was more effective in reducing Cl- accumulation. Furthermore, all of the three kinds of exogenous polyamines could increase the ratio of K/Na, improving the absorption and transport selectivities of K+ and Na+ from stems to leaves for both cultivars. In conclusion, exogenous polyamines could alleviate salt damage to some extent and enhance the accumulation of biomass. Among the three kinds of polyamines, spermidine was most effective. Exogenous polyamines could improve tolerance of cucumber seedlings under salt stress by regulating the absorption and distribution of ions in different organs.
  • WU Qiangsheng, ZOU Yingning, XIA Renxue
    In a potted greenhouse experiment, Citrus tangerine Hort. ex Tanaka was inoculated with arbuscular mycorrhizal (AM) fungus, Glomus versiforme (Karsten) Berch, or non-AM fungus as control. Arbuscular mycorrhizal and non-AM seedlings were grown under well-watered or water-stressed conditions after 97 days of acclimation. The reactive oxygen metabolism of C. tangerine leaves was studied in order to elucidate whether AM symbiosis affects enzymatic and non-enzymatic antioxidants. The results showed that water stress caused a decrement of 33% for the colonization of G. versiforme on C. tangerine roots. Under well-watered and water-stressed conditions, G. versiforme inoculation increased the leaf phosphorus (P) content by 45% and 27%, and decreased the leaf malondialdehyde and hydrogen peroxide contents by 25% and 21%, and 16% and 16%, respectively, compared with the control. Inoculation with G. versiforme enhanced the activities of leaf superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, and increased the contents of leaf soluble protein, ascorbate and total ascorbate notably, regardless of soil moisture conditions. Under water-stressed conditions, G. versiforme inoculation decreased the leaf superoxide anion radical (O2·-) content by 31%. It is concluded that drought resistance of C. tangerine leaves is enhanced due to the improvement of reactive oxygen metabolism after G. versiforme inoculation.
  • GUO Yinqiao, WANG Wenxin, LI Cundong, LIN Yuping, ZHAO Chuande
    Farmland irrigation management and model establishment are always core and difficult contents in crop simulation. This research was focused on exerting the establishment theory of knowledge model, and applying the systematic analysis method and mathematic modeling technology to knowledge expression system of maize water management. Based on soil water balance, a dynamic knowledge model with systematic and wide-application characteristics for maize water management was developed, after periodically quantifying the relationship of irrigation ration between cultivars  characteristics and environmental factors. Cases were studied on the knowledge model with the data sets of normal year in different eco-sites and those of different rain years in the same eco-sites. The results showed that there was no difference in water saving in normal years under different eco-sites, irrigation schedule changes with eco-sites greatly; but a more obvious difference in different rain years of the same eco-sites existing, with 8.6% and 31.9% of water saving in both more rainfall and normal rainfall years, respectively. Additionally, irrigation in the seedling stage did not change with year types, but it did in Knurling and filling stages. This can be concluded that the irrigation regime designed by the model is well coherent to the actual planting system, which indicated that the model had good decision-making and applicability.
  • MA Chunlei, CHEN Liang
    Tea, which has many sanitarian functions, is one of the most popular non-alcoholic soft and healthy beverages in the world. In many countries, as well as in China, tea (Camellia sinensis) is an important cash crop. It has great value as a source of secondary metabolic products. Molecular biology of tea plants has been one of the most active and kinetic research fields of tea science for the last decade. Isolation and cloning of important functional genes of tea plants have a critical significance on elucidating the molecular mechanism of high quality, yield and resistance, as well as genetic manipulating via biotechnological approaches for tea plants. In this paper, we introduced the research progress on the isolation and cloning of functional genes in tea plants. In addition, the brief prospect on the research of functional genes of tea plants in the near future is also given out.
  • Hassan Imran, ZHANG Yuxing, DU Guoqiang, WANG Guoying, ZHANG Jianghong
    This experiment was undertaken to explore the effect of salicylic acid (SA) at different concentrations on regulating fruit senescence of Huang Kum pear. Through dipping fruits and fruit discs for a series of hours in SA solution, enzyme activities and physiological characteristics of Huang Kum pear were determined. The results revealed that SA enhanced the activity of superoxide dismutase (SOD) and peroxidase (POD) enzymes at 0.02 mmol/L and at 0.002 mmol/L with the treatment of dipping fruit discs for 4 h and 12 h, respectively. The malondialdehyde (MDA) contents were reduced at 0.002 mmol/L for 12 h, and water loss ratio was decreased at 0.5 mmol/L after 48 h of treatment. It was concluded that SA at lower concentrations could delay the senescence of Huang Kum pear fruit.
  • ZHENG Weiwei, CHEN Feng, ZHAI Heng, XU Yuehua, ZHANG Jing
    A two-year trial was conducted to test the interactive effects of special-for-apple organic fertilizer, CaSO4, and amino acid Ca on Fuji/Balenghaitang (Malus robusta Rehd.) rootstock in Burozem soil in China. Total Ca, exchangeable Ca, and fruit Ca were significantly improved by the soil application of CaSO4 with the highest exchangeable Ca and fruit Ca observed in Fuji apple trees treated at the rate of 3.5 kg CaSO4 per tree. 3.5 kg CaSO4 was divided into two applications, with first application in the first month after full bloom, and the second in the second month after full bloom in summer, progressively to improve fruit Ca concentration. Dividing CaSO4 into two applications in combination with organic fertilizer or amino acid Ca spray, proved to be more effective on improving the fruit Ca concentration, with the highest level of 179.17 mg/kg FW in Fuji apple trees treated with 2 kg CaSO4 applied and amino acid Ca sprayed in the first month after full bloom, 1.5 kg CaSO4 applied in summer, organic fertilizer applied in winter. Organic fertilizer applied in winter alone remarkably improved the fruit Ca concentration, as well as storage Ca in roots and stems, and the best effect was observed in Fuji apple trees which were supplemented organic fertilizer (10 kg) in winter and CaSO4 (1 kg) in the first month after full bloom per tree. The effect on Ca increment became less pronounced when the amount of organic fertilizer reached 15 kg or CaSO4 was more than 3.5 kg per tree. There was a positive correlation between the Ca/Mg ratio in soil and fruit, exchangeable Ca, and fruit Ca concentration, while a negative correlation was observed between the N/Ca ratio in fruit, available P, available K in soil, and fruit Ca concentration. Both N/Ca ratio and Ca/Mg ratio in fruit were affected by different fertilization regime, and bitter pit incidence at the end of storage kept acceptable only if N/Ca<17 and Ca/Mg≥7 at harvest. The commercial fertilization regime turned out to be organic fertilizer in combination with CaSO4 applied in soil in winter, amino acid Ca sprayed in the first month after full bloom, and CaSO4 applied in soil in summer.
  • LU Jinying, LIU Min, MAO Yongmin, SHEN Lianying
    The current study explored the effects of vesicular-arbuscular mycorrhizae (VAM) inoculation on the growth and water requirement of pot-grown wild jujube (Zizyphs spinosus Hu). Three water regimes (20%, 40% and 60% of soil water content) were conducted. The VAM inoculation could significantly increase plant growth (including plant height, leaf area, and fresh and dry mass), enhance relative leaf water content, photosynthetic rates, transpiration rates and stomatal conductance, and improve plant drought tolerance. The water consumption of the mycorrhizal plants producing 1 g of dry matter was 18.7%–26.6% lower than the consumption of non-mycorrhizal plants grown under the same soil water content conditions.
  • QU Dongyan, YANG Zhangping, GUO Xiaoya, MAO Yongjiang, SUN Wei, GEN Rongqing, REN Xianglian, CHANG Guobing, HUANG Danli, CHANG Hong, MA Yuehui
    The genomes of six populations were screened using microsatellites as molecular markers, including Ujmuqin sheep, small-tailed Han sheep, Tan sheep, Hu sheep, Tong sheep and Yangtse River Delta (YRD) white goat. A total of seven microsatellite markers were used and genetic diversity and genetic distance were also determined. The results showed that there were 224 alleles in six populations, all seven loci showed polymorphism in all populations. The average heterozygosity of all populations was 0.949 9, and the mean polymorphism information content (PIC) of all six populations was 0.842 5–0.929 4. The six sheep (goat) populations were lowly differentiated with all loci, and the coefficient of phaenotype differentiation (Fst) was 2.6%, which was consistent with the coefficient of gene differentiation (Gst). The global heterozygote deficit across of all populations (Fit) amounted to 0.5%. The overall significant deficit of heterozygotes because of inbreeding within breeds (Fis) amounted to -2.2%. Two Unweighted Pair-group Method using Arithmetic Averages (UPGMA) dendrograms were con structed on the basis of Nei s standard genetic distance (DS) and Nei s genetic distance (DA) respectively. Hu sheep and Tong sheep were grouped at first, Ujmuqin sheep and small-tailed Han sheep clustered and then clustered with Tan sheep. Finally, Yangtse River Delta white goat joined in with all above. From this study, Ujmuqin sheep belongs to Mongolia sheep  group, which corresponds with the historical records exactly. Ujmuqin sheep and small-tailed Han sheep, Tan sheep, Hu sheep and Tong sheep all vest in the Mongolia sheep  group.
  • ZHANG Qingru, NI Yaodi, GUO Hongbin, WANG Chunguang
    In order to investigate the effects of a Chinese herbal formula Heat-stress-releasing on the antioxidant function in dairy cows, ten dairy cows were randomly divided into the control group and the experimental group, with five cows in each group. All the cows were fed with a basal diet. The animals in the experimental group were given with 220 g of herbs per day in addition to the basal diet. The trial was conducted for 14 days. Blood samples were taken from the vena cava at day 0, day 7, and day 15, respectively. The antioxidant statuses were examined. The results are as follows. (1) Heat-Stress-releasing formula can significantly increase the milk yield of dairy cows under heat stress. Compared with the control group, the milk yield of the herb-treated group increased by 14.01% (P<0.05), 14.32% (P<0.05) and 15.01% (P<0.05) in prophase, metaphase and anaphase of the test, respectively. (2) Heat-Stress-releasing formula can increase significantly the antioxidant status of the heat stressed dairy cows. Compared with the control group, the superoxide dismutase (SOD) activity increased by 45.93% (P<0.01) at day 7 and by 54.40% (P<0.01) at day 15. The Glutathione-peroxidase (GSH-PX) activity of the test group increased by 17.99% (P<0.05) at day 7 and 25.98% (P<0.01) at day 15. The total antioxidant capacity (T-AOC) of the test group increased by 43.64% (P<0.01) at day 7 and 46.35% (P<0.01) at day 15. The malondaldehyd (MDA) content of test group declined by 23.88% (P<0.01) at day 7 and 25.32% (P<0.01) at day 15.