The MYB-related transcription factors play pivotal roles in regulating plant development and responses to diverse stresses. Functional differences between a MYB transcription factor GmMYB010 in soybean and its orthologous gene AtMYB010 in Arabidopsis thaliana was preliminary analysed in this study. The analysis of amino acid sequences showed that both GmMYB010 and AtMYB010 belonged to the family of R-R-type of MYB-related transcription factors. Subcellular localization exhibited that both GmMYB010 and AtMYB010 were located in the nucleus. The results of qRT-PCR indicated that GmMYB010 had the highest expression level in leaves, while AtMYB010 was expressed in a highlest level in flowers. The GmMYB010 showed strong transcriptional activating functions in yeast, while no transcriptional activating activity was found for AtMYB010. We transformed GmMYB010 gene and its orthologous gene AtMYB010 into Arabidopsis. The results showed that overexpssion of GmMYB010 in Arabidopsis did not cause any changes of phenotypes. However, overexpression of AtMYB010 led to dwarf and more branching phenotypes in transgenic Arabidopsis. The expression analyses of MAXs-related genes indicated that overexpression of AtMYB010 might have affected the arabidopsis development through the strigolactone pathway. Taken together, our study showed that, although GmMYB010 and AtMYB010 were orthologous genes, they had apparently different functions. The specific function of GmMYB010 in soybean needed to be elucidated in futher research.
To better understand the metal ion transport mechanism in AC genomes of Brassica crops, we identified HMA (heavy metal transporting ATPase) genes in Brassica rapa, B. oleracea and B. napus genomes and analysed their evolution. Results showed that a total of 50 candidate HMA genes were identified in AC genomes, including 14 in B. rapa genome, 13 in B. oleracea genome, 23 in B. napus genome (11 in A subgenome, 12 in C subgenome). HMA genes were unevenly duplicated in the 3 species. 50 HMA genes belonged to 3 subgroups (P_1B-1, P_1B-2 and P_1B-4). Among the subgroups, conserved protein sequence distribution, protein properties, and gene structure and the cis-acting elements in promoter region were all different. HMA genes were expressed differently in the same tissue of the same subgroup. 8 HMA genes (including Bra003110, Bol030251, BnaA10g06240D, BnaC09g28870D, BnaC09g11230D, BnaC04g20290D, BnaA09g10950D and Bra027641) were significantly different from AtHMA5. It suggested that these genes might present new functions different from homologous gene AtHMA5 in Brassica crops. Besides, the new variant of GICCSME and GICCPSE in AC genomes was different from A. thaliana HMA genes site GICC(T/S)SE. It might have been associated with new function of the corresponding genes. The present results of the study would shed light on specific functional analysis of HMA genes in Brasscia AC genomes, and could also guide the study of metal ion transport mechanism by HMA genes in Brassica crop.
14-3-3 genes are highly conserved, and they are involved in biotic and abiotic stress response as well as other cellular metabolic processes in soybean genome. Eighteen 14-3-3 genes had been identified and among them 16 genes could be transcribed. In this study, gene expressions of these 16 genes were assayed under phosphorus deficiency in BX10 and TL1, tolerant- and sensitive- phosphorus deficiency cultivar respectively. Six 14-3-3 genes were differentially expressed in BX10 and TL1 under low phosphorus stress. Further analysis indicated that these 6 genes had interaction with soybean phosphate transporter PHT6, suggesting that soybean 14-3-3 proteins might have participated in phosphorus signal channel by interacting with PHT6. The results of this study could assist the application of 14-3-3 genes in soybean genetic improvement.
Kunitz trypsin inhibitor (Kti) from soybean is one of the main inhibitive factors of nutrition. Soybean breeding with low content of trypsin inhibitor was the key to promote the soybean quality. In this study, the consensus sequence of Kti gene in soybean seeds was cloned by RT-PCR, Then, the RNAi vector for silencing Kti gene was reconstructed and transformed to soybean (Jilin 30) by Agrobacterium tumefaciens-mediated method. Five positive transgenic plants were obtained by hygromycin screening and PCR identification. RT-PCR analyses revealed that Kti mRNA was specifically expressed at a low level in transgenic soybean seeds, and the activity of Kunitz trypsin inhibitor decreased about 77.5%. It provided a foundation for further evaluation of RNAi technology for soybean Kti gene regulation.
MicroRNAs (miRNA) are noncoding RNA participating in regulation of many environmental clues. In this study, MIR168 encoding mature miR168 was cloned from soybean genome and ligated to plant expression vector. Tobacco transgenic lines with overexpressed MIR168 were obtained and used to test tolerance to phosphorus deficiency. The transgenic lines grew better than wild type under phosphorus deficiency with longer roots, heavier roots and shoots. The expression of miR168 was higher in transgenic lines than in that of wild type, and the expression of targeted gene AGO1 was higher or equivalent to transgenic lines compared to wild type, indicating that a regulated loop took place between miR168 and AGO1. Seed germination in tobacco transgenic lines with overexpressed MIR168 was inhibited by ABA or JA, suggesting that miR168 was involved in regulating ABA or JA signal pathway. The results could assist the application of soybean miR168 to regulate phosphorus deficiency in plant and breeding of phosphorus-efficient crops.
To increase oil content is the main objective of peanut quality breeding in China，and finding high oil germplasm is the basis for high oil content breeding. It is essential to accurately and rapidly detect oil content in peanut seed without causing damage. In this study, the noninvasive method - nuclear magnetic resonance and national standard method - Soxhlet extraction were both used to detect oil content of peanut seed and there was no significant difference between oil content detected using these two methods, indicating nuclear magnetic resonance method was reliable. A total of 60 peanut cultivars were evaluated for oil content in 4 different areas (Wuhan, Zhoukou, Puyang and Shijiazhuang) using nuclear magnetic resonance method. These results showed significant differences in different environments for oil content. The mean oil content in 60 cultivars was the highest in Shijiazhuang, followed by Wuhan, Puyang and Zhoukou. The cultivars Zhonghua 16, Zhonghua 15 and Jihua 11 had consistent high oil content (>55%) in all four environments. The genetic diversity in 60 cultivars was assessed by using 195 SSR markers. The mean value of gene diversity and polymorphic information content were 0.393 and 0.349 respectively. The genetic distance ranged from 0.049 to 0.731with a mean of 0.388, 23.95% of which was greater than 0.5. The analysis of correlation between SSR markers and oil content showed that 11 SSR markers were highly significantly associated with oil content, and 7 marker loci associated with high oil content, including AGGS1280-288, AGGS1442-201, AHGS0288-182, AHGS1578-266, AHGS1891-276, AHGS2036-200 and GM1940-122. These related marker loci accelerated the progress of marker-assisted selection in future breeding.
To develop high-throughput SNP markers for high quality map of flax (Linum usitatissimum L.), 100 individuals of 2 parents and their F2 population were detected by SLAF-seq technology. They were identified by high-throughput sequencing for SNP marker development and high-density genetic mapping. The 2 parents were varieties R43 and LH-89. After in silico digestion of reference genome, 2 enzymes Hea Ⅲ and Rsa Ⅰ were used to digest the genome DNA. Restriction fragments of 314-414bp were defined as SLAF. Polymorphic SLAFs were analysed and SNPs were detected according to data obtained by high-throughput sequencing. A high-density genetic map was constructed using HighMap software. 196.29M reads were obtained, with average Q30 value of 81.95%, and average GC content 38.64%. 260 380 SNPs were detected, of which 4 547 SNPs were qualified for genetic map construction. The final flax genetic map included 4 145 SNP markers on 15 linkage groups and was 2 632.94 cM in length with an average distance of 0.96 cM between adjacent markers. This first high density genetic map in flax would be essential for genetic study and marker assistant breeding of flax.
To better understand the effect of drought and high temperature on rapeseed (Brassica napus L.), photosynthesis of rapeseed, fast plant variety 29005 was stressed by drought (no irrigation for 6d till the relative soil water content reaching ~15%) and heat (for 7d, 40oC for 16h at daylight, 35oC for 8h in dark for each day) in growth chamber. Changes of photosynthetic and chlorophyll fluorescence parameters were investigated, and key enzymes of photosynthesis were detected. Results showed that plant growth and photosynthesis of 29005 were inhibited under two stresses. Net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) were largely declined under progressive drought stress, while chlorophyll fluorescence parameters [including maximal photochemical efficiency of PSⅡ (Fv /Fm) and maximal photosynthetic electron transport rate (ETRmax)] showed relatively slow decrease. Meanwhile, these 2 parameters were considerably recovered after rewatering for 3 days. Comparing with those under drought stress, Pn, Gs and Tr were decreased slowly after heat stress, and Fv/Fm and ETRmax were sharply declined. Moreover, Fv/Fm and ETRmax were further decreased even after recovery from heat. Rubisco activity was not significantly changed under drought, but decreased obviously under sustained high temperature. The above results indicated that carbon assimilation part in rapeseed photosynthesis was mainly affected by drought, while the inhibition of rapeseed photosynthesis by drought stress was reversible, and the adverse effect on later growth and development was relatively weak after stress recovery. On the contrary, high temperature was more likely to cause irreversible damage to PSⅡ in rapeseed leaves, which further resulted in severe damages on photosynthesis, growth and development of plant.
To better understand the features of winter rapeseed on salty soil, different lines of winter rapeseed (Brassica rapa L.) were studied under NaCl stress. By NaCl simulated experiments, seed germination, seedling physiological characteristics, ionic homeostasisand slip and photosynthetic characteristics of leaves were investigated. The results showed that germination and seedling weight were decreased. The embryonic root and plumule elongation were inhibited. The radicle length/germ length was significantly decreased. But these characteristics were significantly higher in salt-tolerant lines KY-1 and KY-191. With serious salt stress, free proline content increased significantly, while electric conductivity and MDA levels gradually increased. The antioxidant enzymes (SOD, POD and CAT) increased first and then decreased. The salt-tolerant lines had higher enzyme activity and free proline content, and had lower conductivity and MDA content. Na+ contents increased, but K+ content decreased under salt stress. Photosynthetic solid contents were significantly decreased in KY-1 and KY-191. Salt-tolerant strains’ chlorophyll a, chlorophyll b and carotenoid content were higher than those of salt susceptible strains. Tr, Gs, Pn and Ci were significantly higher under salt stress. In conclusion, under salt stress, the salt tolerant lines of Brassica rapa were alleviated by K+ accumulation, osmotic regulator was increased to resist the water potential stress of Na+, and the ability to maintain a good intracellular physiological state and maintain a strong photosynthetic capacity.
To study on changes and relationship of soybean photosynthetic gas exchange parameters in different growth stage, two experiments with 2 soybean varieties and 20 soybean materials were designed. In the first experiment, photosynthetic gas exchange parameters of 2 soybean varieties were measured with Li6400XT on 9 growth stages: VC, V3, V5, R1, R3, R5, R6, R6.5, R7. Chlorophyll contents were measured with SPAD on the same leaves. In the other experiment, 20 soybean materials were used to research the relationship of the photosynthetic gas exchange parameters between V3 and V9 growth stage. Results showed that two soybean varieties photosynthetic capacity was much higher from V3 to R6. And that was highest on R5 and R6 growth stage. Chlorophyll content showed the same trend. Pn, Gs, Tr and SPAD were decreased rapidly after R6 growth stage. Pn, Gs and WUE in V3 growth stage were unrelated to that in V9 growth stage. Tr and Ci of V3 growth stage was significantly related to that of V9 growth stage (r=0.518, P=0.007 and r=0.523, P=0.018). And Pn of V3 and V9 growth stage was unrelated to the soybean yield. Data multiplied by Pn of V3 and V9 growth stage and days of soybean whole growth stage was related to yield significantly (r=0.561, r=0.612). Pt (data multiplied by average Pn value of those 2 growth stages and days of soybean whole growth stage) were significantly related to yield (r=0.676).
High-oil peanut cultivar Hua U606 and medium-oil cultivar Hua17, were used to analyze the changes of their oil content and composition of fatty acid at development and germination stages. The results showed that fatty acid and oil content of two materials varied consistently. The composition of fatty acids lay on “S” curve in the seed development stages. Linolenic acid appeared only in young seeds. In post-germination stages fatty acid composition of Hua U606 changed significantly, and new fatty acids C22:6 were detected comparing to Hua17, indicating the difference of degradation pattern between two cultivars in germination stages. This study preliminary revealed the dynamic changes of lipid and fatty acid in different stages and provided better understanding of the molecular mechanisms for high-oil peanut germplasm.
To optimize the management of irrigation and nitrogen fertilizer and to develop a e regulation mode for high yield and high efficiency in peanut, the field micro-irrigation experiment was conducted under rainproof condition by a random block design with two factors, peanut cultivar ‘Huayu 25’ was planted to investigate the growth form and yield of peanut in response to irrigation and nitrogen fertilizer. The results showed that water and nitrogen had significant effects on the growth and yield of peanut. The single effect of irrigation on the plant growth indexes ( including main stem height, the first lateral branch length, stem diameter, single leaf areas, shoot and root biomass, root/shoot ), root indexes ( including root morphology indexes and root activity ), pod yield and economic coefficient of peanut all reached the significance level or highly significance level. Meanwhile irrigation effect was higher than that of nitrogen fertilizer. Except the total root length of peanut, root activity and economic coefficient, all indexes showed the lowest value under the water stress W1. The single effect of nitrogen fertilizer on the plant growth indexes (including main stem height, the first lateral branch length, shoot and root biomass ), root indexes (except total root length), pod yield and economic coefficient of peanut reached the significance level. All indexes of N1 treatment were higher than that of N2 treatment except economic coefficiency, which indicated that proper nitrogen application could promote the growth of peanut plants and roots. The interaction effect of irrigation and nitrogen showed significant effects on root morphology, root activity and yield of peanut. The pod yield, root average diameter, total root volume and total surface area of peanut all reached maximum at N1W2 treatment. Based on the correlation analysis and grey correlation degree analysis of peanut pod yield, roots average diameter，total root volume，the first lateral branch length and main stem height were in turn the most correlated and sensitive indexes for pod yield. In conclusion，it was beneficial to root growth and higher yield when the amount of nitrogen fertilizer was 15kg· hm-2 and the irrigation amount was controlled at 228m³ ·hm-2, which could led to better coordination of irrigation and fertilizer.
The differences of different peanut genotype varieties on major nutrient element uptake, distribution and utilization were studied by field experiment with split-plot randomized block design, in order to provide technical support on peanut with high-efficiency fertilization on vertisol soil in main peanut area of southern Henan province. The results showed that fertilization could significantly increase absorption of nitrogen, phosphorus and potassium in peanut. The uptake of nitrogen, phosphorus and potassium in Yuhua 22 were the highest, at 283.6 kg/hm2, 32.8 kg/hm2 and 105.9 kg/hm2 respectively. The absorption of nitrogen, phosphorus and potassium in Yuanza 6 were the lowest, at 274.9 kg/hm2, 28.4, kg/hm2 and 87.3 kg/hm2 respectively. Nitrogen were mainly distributed in kernel and leave of peanut, accounted for 66.7%-71.3%, 11.1%-13.3% of the total nitrogen absorption. Phosphorus was mainly distributed in kernel and stem of peanut, accounted for 67.4%-75.6%, and 12.2%-18.3% of the total phosphorus uptake. Potassium was mainly distributed in stems and kernel of peanut, accounted for 41.2%-49.4%, and 18.3%-26.5% of the total potassium absorption respectively. The distribution proportion of nitrogen, phosphorus and potassium in peanut leaf, stem, root, kernel and peanut shell had obvious difference among different peanut genotype varieties. NPK nutrient efficiency of Yuanza 9102 was the highest at 27.7%; that of Yuhua 22 was the second at 25.6%; and that of Yuanza 6 was the lowest at 21.6%. In our experimental condition, rate of N, P2O5, K2O were applied at 150 kg/hm2, 90 kg/hm2, 150 kg/hm2 respectively. Yuanza 9102 was a variety with high utilization efficiency of nitrogen and potassium; Yuanza 6 was a variety with low utilization efficiency of nitrogen and potassium; Yuhua 22 was a variety with high phosphorus efficiency and low nitrogen efficiency.
The causal agent of peanut scab disease is difficult to isolate due to its extremely slow growth and difficult to sporulate on agar media. In this study, an efficient technique for tissue isolation and single-spore isolation of the pathogene was established. Results showed that pathogen isolation frequency from leaves was significantly higher than that of stems. The optimum surface-sterilizing time was 1-3 min, sampling time and storage time within 48h after sampling had no significant influences on isolation frequency. Abundant single-spore colonies could be obtained by improved dilution-plate method, the number of single-spore colonies on peanut leaf decoction agar (PLDA) was more than that on PDA medium, PLDA could inhibit undesired microbes significantly. The number of single-spore colonies obtained by dilution-plate method at early and middle stage of infection was significantly greater than that of late stage, few single-spore colonies were obtained at the late stage .
To find out the accurate reference genes for gene expression analysis of Macrophomina phaseolina by qRT-PCR, 11 housekeeping genes were detected in the pathogenic process. According to PCR amplification efficiencies, 8 housekeeping genes were retained and their expression stabilities were evaluated by computer algorithms GeNorm. The 8 genes included ubiquitin-conjugating enzyme gene UBC, glyceraldehyde-3-phosphate dehydrogenase gene GAPDH, ribosomal protein S5 gene RPS5 (as RPS5-a and RPS5-b), α-tubulin gene TUBA, β-actin gene ACTB, γ-tubulin gene TUBC and internal transcribed spacer ITS. Using qRT-PCR. The expression stability of the 8 genes from sesame samples were investigated at 8 h, 16 h, 24 h and 32 h post M. phaseolina inoculation. GeNorm analysis revealed that the most stable genes were ACTB, GAPDH and RPS5-b. They showed their housekeeping genes features, and could be used jointly as reference genes of M. phaseolina for plant-microb interaction analysis.
Rapeseed combine harvesting was accompanied by sclerotia (Sclerotinia sclerotiorum) remnant in field, which might lead to more serious Sclerotinia stem rot on rapeseed of the next year. To prevent the infection, mycoparasite and cellulose decomposer fungi Trichoderma harzianum strain TRI-5 was used to control the disease. Dissolved powder of TRI-5 was sprayed to stalks immediately after rapeseed was harvested. Under laboratory condition, TRI-5 grew well on sclerotia at 60h after the spore solution spray. The result of scanning electron microscopy showed that sclerotia tissue structure was broken thoroughly. Under field plot experiment, results showed that 30 d after the spore solution spray, sclerotia germination rate was 22.06% lower, while rapeseed stalks decomposition rate increased 14.36% (P < 0.05). In rice yield, it led to 1.72% increase of rice yield (not significant, P > 0.05). It suggested the efficacy of T. harzianum spore solution on Sclerotinia stem rot biocontrol.
Ｓｈｅｗａｎｅｌｌａｂａｌｔｉｃａ６－４２，ａｒｅｃｅｎｔｌｙｄｉｓｃｏｖｅｒｅｄｍａｒｉｎｅｂａｃｔｅｒｉｕｍｆｒｏｍＡｒｃｔｉｃｉｓａｂｌｅｔｏｓｙｎｔｈｅｓｉｚｅ ｖｅｒｙｌｏｎｇｃｈａｉｎｐｏｌｙｕｎｓａｔｕｒａｔｅｄｆａｔｔｙａｃｉｄ，ｅｉｃｏｓａｐｅｎｔａｅｎｏｉｃａｃｉｄ（Ｃ２０∶５，ＥＰＡ）ａｔｌｏｗｔｅｍｐｅｒａｔｕｒｅ．Ｉｎｔｈｉｓｓｔｕｄｙ，ｔｈｅｗｈｏｌｅｇｅｎｏｍｅｓｅｑｕｅｎｃｅｓｏｆＳ．ｂａｌｔｉｃａ６－４２ｗｉｔｈｈｉｇｈ－ｑｕａｌｉｔｙｔｏｔａｌｌｅｎｇｔｈｏｆ５１５Ｍｂｗａｓｆｉｒｓｔｓｅｑｕｅｎｃｅｄｂｙｕｓｉｎｇｔｈｅｔｈｉｒｄｇｅｎｅｒａｔｉｏｎｈｉｇｈ－ｔｈｒｏｕｇｈｐｕｔｓｅｑｕｅｎｃｉｎｇｔｅｃｈｎｏｌｏｇｙ．ＡｎａｌｙｓｉｓｏｆｇｅｎｏｍｉｃｄａｔａｓｈｏｗｅｄｔｈａｔＧＣ ｃｏｎｔｅｎｔｗａｓ４６．１７％ ａｎｄｔｈｅｒｅｗｅｒｅ４５９７ｏｆｉｄｅｎｔｉｆｉｅｄｇｅｎｅｓ．２５７７ｏｆｔｈｏｓｅｇｅｎｅｓｈａｄｃｌｅａｒｂｉｏｌｏｇｉｃａｌｆｕｎｃｔｉｏｎｓ． Ｏｆｔｈｅｍ，３４８ｇｅｎｅｓｉｎｖｏｌｖｅｄｉｎｒｅｇｕｌａｔｉｏｎｏｆｅｎｖｉｒｏｎｍｅｎｔａｌａｄａｐｔａｂｉｌｉｔｙ，ａｎｄ６０ｇｅｎｅｓｉｎｖｏｌｖｅｄｉｎｌｉｐｉｄｍｅｔａｂｏｌｉｓｍ ｐａｔｈｗａｙ．Ｔｈｅｒｅｗｅｒｅ６４０５３ｍｅｔｈｙｌａｔｉｏｎｍｏｄｉｆｉｃａｔｉｏｎｓｉｔｅｓｉｎｔｈｅｗｈｏｌｅｇｅｎｏｍｅ，ａｎｄｍ６Ａａｎｄａｓｍａｌｌａｍｏｕｎｔｏｆ ｍ４Ｃｗｅｒｅｍａｉｎｌｙｍｏｄｉｆｉｃａｔｉｏｎｔｙｐｅｓ．Ｂｙｈｏｍｏｌｏｇｏｕｓｓｅｑｕｅｎｃｅａｌｉｇｎｍｅｎｔ，５ｋｅｙｇｅｎｅｓａｎｄ１ｒｅｇｕｌａｔｏｒｉｎｖｏｌｖｅｄｉｎ ｐｏｌｙｋｅｔｉｄｅｓｙｎｔｈａｓｅｐａｔｈｗａｙ（ＰＫＳ）ｗｅｒｅｉｄｅｎｔｉｆｉｅｄ．ＴｈｅｙｃｏｕｌｄｂｅｒｅｓｐｏｎｓｉｂｌｅｆｏｒＥＰＡｓｙｎｔｈｅｓｉｓｉｎＳ．ｂａｌｔｉｃａ６－ ４２．Ｏｔｈｅｒｋｅｙｇｅｎｅｓｏｒｇｅｎｅｃｌｕｓｔｅｒｓｉｎｖｏｌｖｅｄｉｎｆａｔｔｙａｃｉｄｓｙｎｔｈｅｓｉｓａｎｄｓｅｃｏｎｄａｒｙｍｅｔａｂｏｌｉｔｅｓｗｅｒｅｐｒｅｄｉｃｔｅｄａｓ ｗｅｌｌ．Ｔｈｅｗｈｏｌｅ－ｇｅｎｏｍｅｃｏｍｐａｒａｔｉｖｅａｓｓｏｃｉａｔｉｏｎａｎａｌｙｓｉｓｗａｓｐｅｒｆｏｒｍｅｄｂａｓｅｄｏｎｅｘｉｓｔｉｎｇｇｅｎｏｍｉｃｉｎｆｏｒｍａｔｉｏｎｏｎｓｔｒａｉｎｓＳ．ｂａｌｔｉｃａＯＳ１５５ａｎｄＯＳ６７８．Ａｌｔｈｏｕｇｈａｌｌ３Ｓ．ｂａｌｔｉｃａｓｔｒａｉｎｓｐｒｅｓｅｒｖｅｄＰＫＳｇｅｎｅｃｌｕｓｔｅｒ，ｔｈｅｅｖｏｌｕｔｉｏｎａｒｙ
ｄｉｆｆｅｒｅｎｃｅｏｆｍｏｓｔｆｕｎｃｔｉｏｎａｌｇｅｎｅｓｗａｓｑｕｉｔｅｄｉｓｔｉｎｃｔ．ＴｈｉｓｓｔｕｄｙｐｒｏｖｉｄｅｄｄａｔａｂａｓｅｆｏｒｔｈｅｅｘｐｌｏｉｔａｔｉｏｎａｎｄａｐｐｌｉｃａｔｉｏｎｏｆｆｕｎｃｔｉｏｎａｌｇｅｎｅｓｉｎｃｌｕｄｉｎｇＥＰＡｓｙｎｔｈｅｓｉｓｒｅｌａｔｅｄｇｅｎｅｓｆｒｏｍＳ．ｂａｌｔｉｃａ６－４２．
A new pest Leptomias sp. was found on oilseed rape in Linzhi, Tibet, China in 2014. It belongs to Coleoptera, Curculionidae, Leptomias Faust. Field survey showed that Leptomias sp. mainly distributed in Bayi town, Linzhi, Tibet, China. The adults damaged cotyledons and leaves, and the larvae damaged roots. The morphological characteristics of adult, egg, larva and pupa were described.
To determine the difference and main factors of yield performance of Brassica napus between China and Canada, registered varieties’ data were analized in these 2 countries from 2013 to 2015. The results showed that the average yield of registered cultivars in China (winter rapeseed, the main production in Chinese ) were 2 950.4 - 3 112.9 kg/hm2, and the mean yield were 3 496.5 - 4 689.8 kg/hm2 in Canada. In national trials, the average yield was 4 057.8 kg/hm2 in Canada, which was 34.1% higher than that from China (3 026.2 kg/hm2). Compared with Chinese cultivars, Canadian varieties showed better adaptabilty and stability. In consideration of population structure, Canada varieties had higher planting density which resulted in higher yield performance, while those from China relied more on excellent yield of single plant. These comparision suggested that Chinese rapeseed breeding should be changed from excellent single plant to higher planting density and better population structure.
