2022 Vol. 37, No. 3
Display Method:
2022, 37(3): 273-282.
doi: 10.19303/j.issn.1008-0384.2022.003.001
Abstract:
Objective To optimize N×S interactions at differentiated habitats for maximal yield and fertilizer use efficiency of fragrant rice. Methods A split-plot experiment was conducted in 2018 at two typically different fragrant rice production areas, Habit 1 at Jiangmen, Guangdong and Habit 2 at Chenxi, Hunan. The main lots were designed for varied applications of N and S, while the sublots for planting of two cultivars of high-quality fragrant rice. The N application rates included 0 (N1), 90 kg·hm−2 (N2), and 180 kg·hm−2 (N3), and the S at 0 (S1), 45 kg·hm−2 (S2), and 90 kg·hm−2 (S3). A total of 9 treatments of combined N×S applications, i.e., N1S1 (control), N1S2, N1S3, N2S1, N2S2, N2S3, N3S1, N3S2, and N3S3, with 3 replicates on the randomly distributed sublots were implemented. Results (1) Because Habit 2 had a wider range of daily temperatures, cooler night temperature, longer growing period for the rice, and greater ability of the red paddy soil to retain water and fertilizer than Habit 1, the rice grown on Habit 2 had significant higher yield, number of productive spikes, and total grain number per panicle (P＜0.01). (2) N3S3, N3S2, N2S2, N2S1, N2S3, and N3S1 significantly increased the rice yield and N3S2, N2S2, N2S1, N2S3, and N3S1 significantly raised the number of productive ears per unit area, seed setting rate, and 1 000-grain weight of the rice but significantly reduced the total grain number per panicle (P＜0.01). (3) At Habit 1, N2S3 significantly increased the yield and N use efficiency of the rice variety, Xiangwanxian No.13. At Habitat 2, the yield and N and S use efficiency of Xiangwanxian No.17 were significantly increased by N3S2 with the increases ranking as N3S2＞N3S3＞N2S1＞N2S2＞N3S1＞N2S3 (P＜0.01), which were significantly higher than those for Xiangwanxian No.13. (4) The N use efficiency of Xiangwanxian No.13 at Habit 1 increased and then decreased parabolically with increasing S. The S use efficiency of rice plants reached a peak of 24.44 kg·kg−1 under N3S2 and declined at a high S application level, such as N2S3 and N3S3. On the other hand, the N use efficiency of Xiangwanxian No.17 in Habit 1 increased with increasing S under N2, but so did N3S3. On the S use efficiency of the rice plants, the parabolic effect of N was also observed with N2S3 yielding the maximum at 4.85 kg·kg−1. (5) The N utilization by Xiangwanxian No.13 at Habit 2 improved with S application, but the S use efficiency peaked at 19.11 kg·kg−1 under N2S2. Whereas Xiangwanxian No.17 showed a decreased N use efficiency upon increasing S, as well as the S use efficiency decreased from 69.27 kg·kg−1 under N3S2 to that under N3S3. Conclusion To varying degrees habitat, cultivar, and N×S interaction all affected the yield, yield components as well as the N and S use efficiency of the fragrant rice. N2S3 significantly increased the yield and N use efficiency of Xiangwanxian No.13, and N3S2 of Xiangwanxian No.17.
2022, 37(3): 283-290.
doi: 10.19303/j.issn.1008-0384.2022.003.002
Abstract:
Objective To fully utilize existing glabrous rice resources, build superb rice restorer lines, and breed new high-quality, disease resistant varieties of rice. Method Hybridization using the glabrous Australia-112 as the female parent and the blast-resistant restorer line Minghui 77 as the male parent was conducted. After pedigree selection with blast resistance confirmation, the rice cultivar HN476 was chosen to cross with the sterile line Funong A to arrive at a new restorer line Quanhui 404. The combination of Quanhui 404 and Funong A, Funong You 404 were subjected to multipoint variety comparative tests in 2016-2017 at Hui’an and Dehua counties in Fujian as well as at Sanya in Hainan. It performed well with high yield and rice blast-resistance at the Regional Trials of Seed Enterprises Consortium on Mid-season Rice Varieties in Sanming City in 2018 prior to entering trials and production tests in 2019 and 2020. Result The mean yield of the newly bred Funong You 404 was 8 721.75 kg·hm−2 at the regional trials in two consecutive years which was 1.96% higher than that of the reference variety, II You 3301. Overall, it exhibited high and stable yield, moderate resistance to blast, the grade-3 edible rice variety grain quality standard set forth by the Ministry of Agriculture, and the certificate issued by the Crop Variety Approval Committee of Fujian in 2021. Conclusion Funong You 404, the new 3-line hybrid rice variety, was characterized by high yield, desirable grain quality, and blast resistance. It was considered suitable for mid-season rice cultivation in Fujian.
2022, 37(3): 291-301.
doi: 10.19303/j.issn.1008-0384.2022.003.003
Abstract:
Objective Crayfish- rice mode is the important mode for agriculture production in Hubei and even southern China. Lodging is one of the main factors that affect the yield of rice. The study on the suitable nitrogen application rate of direct seeding shrimp rice can provide a theoretical basis for its rational fertilization. Method Under the continuous cropping mode of crayfish-rice, using typical crayfish-rice varieties Yuzhenxiang, Huanghuazhan and Efengsimiao as experimental materials and no fertilization as control（CK）, a split plot experiment was set up at three nitrogen application levels (120, 150 and 180 kg · hm − 2) to explore the effect of nitrogen application rate on the lodging resistance of direct seeding crayfish-rice. Result With increasing N application, the internode length, plant height, and gravity center height, bending momen of the 4th and 5th internode from the top, and big and small vascular bundles number of the 4th internode from the top of the rice plants increased, while the breaking momente, big and small vascular bundles area, and culm wall thickness increased initially followed by a decline, and the lodging index decreased at first and then rose. Conclusion The lodging resistance of the crayfish-rice cultivated rice plants in response to different N fertilizations varied among the 3 varieties. The optimal N application rate for Yuzhenxiang was 120 kg·hm−2, for Efengsimiao 120-150 kg·hm−2, and for Huanghuazhan 150 kg·hm−2.
2022, 37(3): 302-309.
doi: 10.19303/j.issn.1008-0384.2022.003.004
Abstract:
Objective Effects of gibberellic acid (GA3) and 2, 4-ebrassinolide (EBR) on grain-filling and yield of Tartary buckwheat were studied. Method Grain-filling and starch synthase activity of dominant and weak Tartary buckwheat grains under 6 treatments of GA3 and/or EBR were compared. Antioxidant enzyme activity and photosynthetic properties of the leaves during grain-filling stage and agronomic traits associated with grain yield of the plants were monitored. Result Compared to control, GA3 alone significantly increased the 100-grain weight and activities of adenosine diphosphate glucose coke phosphorylase and soluble starch synthase in the grains as well as the antioxidant enzyme activities, net photosynthetic rate, stomatal conductance, and transpiration rate in the leaves. It also significantly increased the yield per plant and final grain yield. Increasing EBR application, on the other hand, increased the activities of starch synthase, leaf antioxidant enzymes, leaf photosynthetic characteristics, main stem branch number and diameter, grains per plant, grain weight per plant, and final grain yield initially but declined after reaching a peak. Meanwhile, the number of main stem nodes and plant height rose and the starch synthase activity of the weak grains lowered continuously. Conclusion By combining GA3 at the rate of 80 mg·L−1 and EBR at 0.5 mg·L−1 for treating Tartary buckwheat, the grain-filling of dominant grains was enhanced, the leaf senescence delayed, and the grain weight and final yield increased.
2022, 37(3): 310-316.
doi: 10.19303/j.issn.1008-0384.2022.003.005
Abstract:
Objective Effects of returning mushroom discards to the field on soil and quality and yield of off-season cultivated yams were investigated. Method In a field experimentation Nahuai No. 1 yams were planted off-season on lots added with mushroom discards (T1), an organic fertilizer (T2), mushroom discards + an organic fertilizer (T3), or blank control (CK) to determine the quality and yield of the yams grown on them. Result The treatments significantly increased the tuber yield over CK with T3 delivered the greatest at 39,328.63 kg·hm−2, which was significantly higher than other treatments—T1 increased by 15.53%, T2 by 17.92%, and T3 by 26.53%. The starch content in the tubers increased with T3 producing the significantly highest at 30.84%; the amino acids ranged between 2.38% and 2.47%; the highest soluble sugars came from yams grown on T2; the highest saponin among all at 0.46 mg·g−1; and the leaf chlorophyll heightened in 10-160d after emergence with the highest peak value and the slowest on declining under T3. The treatments, especially T3, also altered the soil nutrients increasing the available nitrogen, phosphorus, potassium, and organic matters, while balanced the pH. Conclusion By returning mushroom discards with added organic fertilizer to the soil, T3 significantly improved the yield and quality of the yams grown on the treated land.
2022, 37(3): 317-325.
doi: 10.19303/j.issn.1008-0384.2022.003.006
Abstract:
Objective Yield and N-uptake of cotton plants in response to N applications and factors affecting the reaction were quantitatively analyzed with documented database. Method Meta analysis was conducted on 43 relevant articles published from 2002 to 2019 to compare the effects of the planting time, area, and N fertilization as well as the soil type, density, organic matters, total N, alkali-hydrolysable N, available phosphorus, and available potassium on the yield and N-uptake of cotton plants with those without any N application. Result The increase of 36% on yield and 51% on N-uptake of the cotton plants in 2008–2013 were significantly higher than 20% and 34%, respectively, in 2002–2007 or 28% and 33%, respectively, in 2014–2019. Increased N application promoted both yield and N-uptake of cotton plants more from the first data collection period to the second period than from the second to the last 5 years. Cotton yield and N-uptake were significantly higher with N application 300–450 kg·hm−2(38%, 58%) than N application more than 450 kg·hm−2(30%, 54%) or less than 300 kg·hm−2 (27%, 31%). There were regional variations on the effects as well. For instance, in northwest China, the fertilization resulted in the greatest increase on yield at 45% but the least on N-uptake at 35%, whereas the least on yield at 25% and the greatest on N-uptake at 65% in central China and the medium on yield at 33% and N-uptake at 38% in eastern China were observed. Increases on planting density tended to reduce the cotton yield and N-uptake. Soil type also affected the yield and N uptake as they increased significantly more in clay soil (40% and 56%, respectively) than in sandy loam (25% and 28%, respectively) and loam (36% and 39%, respectively). Grown on soil containing organic matters more than 15 g·kg−1, alkali-hydrolyzable N in the range of 50–100 g·kg−1, available phosphorus between 15–30 mg·kg−1, and available potassium greater than 300 mg·kg−1, the cotton yield was higher than without N application. And the soil containing organic matters in the range of 10–15 g·kg−1, total N more than 1.6 g·kg−1, alkali-hydrolyzable N higher than 100 g·kg−1, available phosphorus between 15–30 mg·kg−1, and available potassium less than 200 mg·kg−1 produced higher cotton N-uptake than without N fertilization. Conclusion Application of 300-450 kg·hm−2 of N fertilizer on the filed appeared to be critical for high cotton yield.
2022, 37(3): 326-334.
doi: 10.19303/j.issn.1008-0384.2022.003.007
Abstract:
Objective Roles of phosphorus application on growth and root mycorrhizal infection rate of tomato seedlings intercropped with potato-onion were investigated to optimize the fertilization for sustainable crop production and agricultural ecosystem. Methods Tomato (Solanum lycopersicum L.) seedlings were either grown under monoculture (T) or intercropping with potato-onion (Allium cepa L. var. aggregatum G. Don) (TO) in a pot experiment. Biomass, root mycorrhizal infection rate, and nutrient concentrations of the tomato plants, as well as the nutrient contents in the soil treated with varied phosphorus applications, i.e., 0 P (P0), 250mg P·kg−1 (P250), 500mg P·kg−1 (P500), and 1,000mg P·kg−1 (P1000), were monitored. Results Compared to P0, the dry weight of the monocultured tomato plant under P250 increased by 43.18%, under P500 by 47.73%, and under P1000 by 47.02%, while the intercropping under P250 resulted in an increase of 45.93%, under P500 50.36%, and under P1000 40.89%. At same P application level from T to TO, the tomato plant weight increased 8.8% under P0, 13.6% under P250, 15.2% under P500, and 5.6% under P1000. P250, P500, and P1000 enhanced the biomass production as well as the nutrient concentration and uptake of the tomato plants. The applications also increased the available P and K in soil with a significant positive correlation. At P500, the greatest and significantly higher than other treatments on plant biomass and root mycorrhizal infection rates of the tomato plants were observed. Conclusion P played an important role in the interaction between tomato and potato-onion. At the 500 mg·kg−1 application level, P maximized the interaction and enhanced the tomato root mycorrhizal infection which facilitated transfer of nutrients from soil to plant promoting the growth.
2022, 37(3): 335-343.
doi: 10.19303/j.issn.1008-0384.2022.003.008
Abstract:
Objective Effects of laser and light-emitting diode (LED) exposures on growth, photosynthesis, and physiological and biochemical characteristics of Solanum lycopersicum seedlings were investigated. Method A CIRAS-3 system was used to determine the photosynthetic response of 30-d-old tomato seedlings exposed to 2 red and 1 blue monochromatic laser or LED. Then, using a color temperature of 6 000 K white LED as control the seedling growth under the LED white light supplemented with a small amount of blue light along with the photosynthesis-stimulating red light as treatments was compared. Result The photosynthetic capacity of the seedlings exposed to 650nm red light was greater than the other wavelengths of red light when the photosynthetic quantum flux density PPFD was below 400 μmol·m−2·s−1. The capacities produced by laser of 650 nm and 450 nm were greater than LED of same wavelengths. The growth indicators, maximum net photosynthetic rate, and water use efficiency of the seedlings exposed to either laser or LED was greater than control, but laser significantly higher than LED (p＜0.05). All treatments had a same light compensation point, but the seedlings grown under white LED supplemented with both 650 nm and 450 nm laser had the lowest light saturation point. In addition, laser was significantly more effective than LED in increasing the contents of chlorophyll a, carotenoid, and malondialdehyde (MDA) and the activity of peroxidase (POD), although it did not affect the superoxide dismutase (SOD) activity. Conclusion The white LED supplemented with laser, especially both 650nm and 450nm, significantly promoted the growth, photosynthetic capacity, and antioxidant activities of the tomato seedlings in comparison to LED supplementation.
2022, 37(3): 344-353.
doi: 10.19303/j.issn.1008-0384.2022.003.009
Abstract:
Objective An open tissue culture with added bacteriostatic agents in medium for disinfection and disease prevention was established and genetic stability of the plantlets verified for the development of commercialized propagation of rhododendron. Method Terminal buds and stem segments with attached axillary buds were cut from current year branches of Rhododendron pulchrum Sweet plants. Methods using bacteriostatic agents in varied concentrations to disinfect the cut tissues and prevent infection during proliferation stages in an open tissue culture were evaluated. Genetic of the materials in transition from parent to plantlet was scrutinized using an ISSR molecular marker technology to ensure a reliable stability in the process. Result The explants could be adequately disinfected with 10% H2O2 for 10 to 15m. A survival rate of terminal buds at 61.67% with a contamination rate of 33.33% and that of stem segments at 23.33% with a contamination rate of 68.33% were achieved. For the open tissue culture, 0.01% addition of NaClO in the medium was found sufficient to achieve the bacteriostatic effect with a survival rate of 62.22% on the plantlets, which had abundant, slender, new leaves and a proliferation coefficient of 3.067. The ISSR molecular maker analysis showed high genetic similarity coefficients ranging from 0.919 to 0.995 between the disinfected explants, the test-tube buds, and the exophyte plantlets. Conclusion This study preliminarily explored the open tissue culture for the feasibility of rhododedron tissue factory nursery. The cut rhododendron tissues for the culture was satisfactorily disinfected with 10% H2O2 in 10-15 m. The survival rate of terminal buds after the treatment was higher than that of stem segments. In the early stage of the open tissue culture, a 0.01% addition of NaClO in medium provided sufficient bacteriostatic effect without significant reduction on the survival rate and proliferation coefficient of the treated plantlets. The genetic distance between the parent and the explants remained close, indicating little variation introduced by the propagating operation. The disinfection method and culture procedure appeared feasible for the development of rhododendron seedling generation at nurseries.
2022, 37(3): 354-363.
doi: 10.19303/j.issn.1008-0384.2022.003.010
Abstract:
Objective Correlation between soil nutrients and amino acids content of fresh tea leaves in autumn was analyzed to optimize the cultivation. Method Based on the projected importance of variables, indices on soil nutrients that significantly affect the amino acids in fresh tea leaves were used in a partial least squares regression analysis to establish linear programming equations. A scheme to optimize the amino acids synthesis and accumulation in tea leaves through soil management was formulated using LINGGO software. Result Correlations between the amino acids in fresh tea leaves and the nutrients in the cultivation soil were obtained. The optimal soil pH for amino acids accumulation in tea leaves was in the range of 4.39 and 4.85, the organic matters at 31.91g·kg−1 (that for taurine and glycine, 34.6 g·kg−1), the total phosphorus 0.44–0.52 g·kg−1, the total potassium at 20.01 g·kg−1, the total nitrogen 1.73–2.13 g·kg−1, the available phosphorus 178.27–219.77 mg·kg−1, the available potassium 180.38–196.54 mg·kg−1, and the available nitrogen 73.22–143.48 mg·kg−1. Conclusion Different soil nutrients affected the composition of tea leave amino acids differently. A plantation managed to use organic fertilizer, mitigate acidification, and apply ample nutrients, especially available nitrogen, in the cultivation soil could significantly increase the amino acids content in tea leaves harvested in autumn.
2022, 37(3): 364-370.
doi: 10.19303/j.issn.1008-0384.2022.003.011
Abstract:
Objective Adults and larvae of Papilio Polytes were studied with the complete mitochondrial genome sequenced for the butterfly genomics library collection. Method According to the morphological characteristics of wing markings, sequences of the mitochondrial genomes of P. Polytes were determined using the second-generation Illumina Hiseq 4 000 high-throughput sequencing technology. Result The wing markings of P. polytes polytes was found significantly different from those of P. polytes tibetanus’s. The length of complete mitochondrial genome was 15 267 bp (GenBank accession no. MZ188895) consisting of 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and a control region. The average contents of A+T was 80.6% of the entire sequence representing a significant A+T deflection that had 11 gene intervals and 12 gene overlaps. Except Cox1, all protein coding genes started with ATN, whereas Cox2 ended with codon T. The nucleotide composition showed a significant AT skew. The relative synonymous codon usage (RSCU) of UUA was the highest one. Other than trnS1, the transfer RNAs had the typical clover-leaf-like structure with U-U or U-G base mismatched in the secondary structure and 9 transfer RNAs without mismatch. The A+T average content was the highest in control region at 94.5%. Conclusion Morphologically, P. polytes polytes and P. polytes tibetanus mainly differed in location and distribution of the elements. The structures and sequences of the genomes of P. Polytes mitochondria as determined were in line with those of Lepidoptera insects.
2022, 37(3): 371-380.
doi: 10.19303/j.issn.1008-0384.2022.003.012
Abstract:
Objective Inhibitory activities and antagonistic mechanisms of Bacillus velezensi (Bv) strains against certain soil-borne pathogens were studied in search for new venues of biological disease control. Method Antagonism of 6 Bv strains, NN01, NN02, NN04, NN05, NN88, and NN95, on 7 soil-borne pathogens, Fusarium oxysporum f. sp. cubense, Sclerotinia sclerotiorum, Scleritium rolfsii, Botrytis cinerea, Rhizoctonia solani, and Phytophthora nicotianae, were studied using a plate confrontation test. Morphological responses of the pathogen mycelia to the Bv strains were observed under an optic microscope, and the control efficacy verified in vitro on mulberry and lettuce leaves. Activities of the extracellular enzymes (e.g., cellulase, protease, and β-1,3-glucanase) produced by the Bv strains were identified with differential media, and 10 antibiotic-related genes (i.e., mycB, fenB, ituA, sfp, bamC, Erisa, spaS, bacA, yndJ, and Qk ) in the bacteria detected by PCR amplification with specific primers. Result To varying extents the 6 Bv strains inhibited the mycelia growth of the 6 target pathogens. The strongest effect was shown on S. rolfsii. NN01, NN02, NN04, and NN88 displayed inhibition rates ranging from 40.56% to 56.30% on F. oxysporum. The appearance of mycelia on edge of inhibition rings changed significantly with broken, leaking intracellular substances, and darked color. In vitro the Bv strains significantly inhibited disease development on the plant leaves by S. sclerotiorum with a control effect of 53.40-71.32% and 43.57-65.68% by S. rolfsii, which were higher than or equal to the inhibition by B. subtilis. All 6 Bv strains secreted proteases and cellulases with the presence of 5 lipopeptide antibiotic-related genes (i.e., mycB, fenB, ituA, bacA, and yndJ), except no fenB found in NN95. Conclusion All 6 Bv strains had varying inhibitory effects against the 7 soil-borne pathogens. They showed extracellular protease and cellulase activities, and almost all of them carried 5 lipopeptide antibiotic-related genes. These Bv strains could potentially be applied as biocontrol agents for control of diseases caused by the soil-borne pathogens.
2022, 37(3): 381-389.
doi: 10.19303/j.issn.1008-0384.2022.003.014
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Objective Effects of addition of a nitrification inhibitor, dicyandiamide (DCD) or 2-chloro-6 (trichloromethyl) pyridine (NP), on the N2O and CO2 emissions and nitrate content in soil and yield and quality of Chinese cabbage grown on the soil in a greenhouse were studied. Method A pot experiment using the soil from a Chinese cabbage greenhouse at Beichakou Village, Daxinge Township, Yongqing County, Langfang City was conducted to grow Chinese cabbage in a static solar greenhouse. A blank control that applied no fertilization (CK) along with 5 treatments that included the addition to the soil of a water-soluble fertilizer (R1), R1(DCD), R1(NP), a liquid sludge nitrogen fertilizer (L), or L(DCD). N2O and CO2 emitted from the soils were collected for the determination using static image-gas chromatography. At harvest, nitrate nitrogen in 0–30 cm depth of soil was measured by a flow analyzer, and yield and quality of vegetables grown on the soil recorded. Result The fertilizations significantly increased N2O emission over CK. However, the addition of nitrification inhibitor reduced the cumulative emission by 45.70% under R1(DCD) and 62.46% under R1(NP) over R1, and that under L(DCD) lower by 45.81% over L. And after topdressing, the cumulative N2O emission under R1(DCD) became 71.54% and R1(NP) 66.81% lower than those under R1, while that under L(DCD) 37.13% lower than under L. On the cumulative CO2, it fluctuated after the fertilizations but no apparent effect shown by the inhibitor applications. In the 0–30 cm soil layer, the nitrate nitrogen concentration increased when fertilizerd with increasing depth and decreased with increasing biochemical regulating fertilizers DCD and NP. The nitrification inhibitors improved somewhat the Chinese cabbage quality and yield but not significantly. R1(DCD) and R1(NP) reduced the nitrate content from R1 by 11.10% and 3.41%, respectively, while L(DCD) did by 7.69% over L. Conclusion Biochemical regulating fertilizer improved somewhat the vegetable yield and quality, while reduced the N2O emissions of the soil benefitting the eco-system.
2022, 37(3): 390-397.
doi: 10.19303/j.issn.1008-0384.2022.003.015
Abstract:
Objective Applications of cattle and sheep manures for fertilization on soda saline-alkali soil in western Jilin Province were compared. Methods Started in 2017 a field experiment for the fertilization study was carried out on a typical soda saline-alkali land in Zhenlai County, Baicheng City, Jilin Province. Three treatments including control and the uses of cattle or sheep dung on the randomly selected lots were designed to generate information on the pH, total soluble salts, exchangeable sodium content, cation exchange capacity, and organic carbon content in soil for the comparison. Results The application of either cow or sheep manure had no significant effect on soil pH, particle size distribution and mean weight diameter of water-stable aggregates. However, cow manure rose the total organic carbon, water-soluble organic carbon, and humus carbon by 27.2%, 55.6%, and 36.8%, respectively, while sheep manure 52.8%, 122%, and 82.1%, respectively. Both applications significantly increased the organic carbon in the water-stable aggregates. However, the total salt, exchangeable sodium, cation exchange capacity, total organic carbon, water-soluble organic carbon, humic acid carbon, humus carbon, water-stable agglomeration body, and ratios of alkyl/aromatic carbon, alkyl/alkoxy carbon, and hydrophobic/hydrophilic carbon were higher, but the alkalinity, and alkoxy/carboxyl carbon and aliphatic/aromatic carbon ratios lower, in the soil fertilized with sheep manure than cow manure. Conclusion The application of cow or sheep manure increased the contents and enriched the components of organic carbons and also improved the quality of organic matters in soil. It did not significantly alter the soil structure in the short term, however. Sheep dung was more effective in ameliorating the soil degradation and in increasing the soil organic carbon, whereas cow manure more conducive to improving the quality of organic matters. Thus, using both materials simultaneously could maximize the effect on soda saline-alkali soil.
2022, 37(3): 398-404.
doi: 10.19303/j.issn.1008-0384.2022.003.016
Abstract:
Objective Enhancing effect of chemical fertilizers on the phytoextraction of king grass (Pennisetum sinese Roxb) on cadmium (Cd) in contaminated soil were evaluated. Method Chemical fertilizers, i.e., NH4Cl, KCl, and CO(NH2)2, at the rate of 0.6 kg·m−2 were applied, along with control, to the soil nearby a cadmium-contaminated mining field for the experimentation. Result The fertilizations significantly increased the aboveground biomass of the king grass in 150 d (P＜0.05). The addition of NH4Cl or KCl raised the Cd concentration in the grass leaves (P Conclusion It was recommended twice a year of 150 d harvest cycle with NH4Cl-fertilization be applied on the Cd-contaminated soil to mitigate the pollution in soil.
2022, 37(3): 405-413.
doi: 10.19303/j.issn.1008-0384.2022.003.017
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Objective Bacteria with a high cellulase-producing capacity were isolated from different varieties of tobacco for the potential of upgrading the economic value of tobacco raw materials. Methods Candidate bacterial strains were isolated and purified from 37 flue-cured tobacco strip samples using dilution coating method. They were screened by the Congo red staining combined with shaking flask culture and cellulase activity determination. Phylogenetic property of a strain identified by morphological observation was confirmed with 16S rRNA sequencing. The cellulase activities were investigated. Results FX-1 was preliminarily identified as a strain that produced high cellulase activity of 56.261 U·mL−1 after 48h fermentation at 37 ℃. It was a gram-positive, rod-shape, spore-producing bacterium that showed a perfectly matching 16S rRNA sequence in a branch of Bacillus subtilis phylogenetic tree. The cellulase from FX-1 displayed a peak activity at 60 ℃ and pH 5.0. Greater than 90% of its relative activity was retained after being held at 30-55 ℃ or pH 3.0-7.0 for 30 min. Conclusion A high cellulase-producing bacterium screened from 37 flue-cured tobacco strip samples was preliminarily identified as a strain of B. subtilis. The cellulase produced by the strain FX-1 exhibited a wide-range temperature and pH stability, and thus, had a considerable potential to be developed for new commercial use in tobacco manufact.
2022, 37(3): 414-422.
doi: 10.19303/j.issn.1008-0384.2022.003.018
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Objective Conditions to achieve high-efficiency secretory expression of the thermophilic α-cyclodextrin glucosyltransferase (α-CGTase) in Bacillus subtilis RIK1285 were explored to understand the role played by signal peptide. Method A library based on 173 signal peptides from B. subtilis was constructed to identify the highest secretion efficiency candidate. Using the saturation mutagenesis of segments in the selected signal peptide, the secretion expression of α-CGTase was enhanced. Result There were 9 signal peptides with high expression efficiency identified from the library. Among them, the signal peptide citH showed the highest secretion efficiency. Subsequently, the saturation mutagenesis of Gly2, Asn3, and Thr4 of citH produced a mutant, G2R-N3K-T4L-CGT, with an extracellular activity of α-CGTase as high as 14.2 U·mL−1 and a secretion efficiency increased by 47.9% over the non-mutated signal peptide (9.6 U·mL−1), which was 21.5 times higher than that of the wild-type Geobacillus caldoxylosilyticus CHB1 (0.66 U·mL−1). The purified α-CGTase had a maximal activity at pH 6.0 and 60 ℃, was thermally stable within 50 ℃, and could be activated by Mg2+ and Ca2+. Conclusion The important effect signal peptide had on the high-efficiency expression of cyclodextrinase in B. subtilis was verified. The result provided a new and valuable reference for studies on the expression of extraneous proteins in the bacteria.
