Pinghong MENG, Houjun XIAO, Jingtao GUO, Xia CAI, Dehuai PAN, Jiyong FU, Guilian LI*

1. Guizhou Horticulture Institute,Guizhou 550006, China;

2. Guizhou Soil and Fertilizer Institute, Guizhou 550006, China;

3. Sandu Development Station of Fruits and Vegetables, Sandu 558100, China;

4. Fuquan Station of Fruits and Vegetables, Fuquan 555800, China

In recent years, using the limited land resources and playing climatic and ecological advantages,a series of vegetable efficient planting modes suitable for different altitude areas of Guizhou were studied and applied in production, such as "early spring Chinese cabbage-summer and autumn eggplant-autumn and winter asparagus lettuce", "wild cabbage-Chinese cabbage-wild cabbage" and"pepper intercropping spring Chinese cabbage-autumn and winter asparagus lettuce", which improved multiple cropping index and output value per unit of land, and obtained better economic benefit. Vegetable industry has become characteristic advantage industry of Guizhou key development.Different crop varieties and planting modes have varying influences on soil quality of different habitats.Researches of Wang Shan et al. showed that biological character of soil could sensitively reflect soil quality change, was indispensable indicator for soil quality evaluation, and received more and more attention[1-3].Biological indicators of soil included plant, animal and microorganism growing in soil, in which soil microbial index was widely applied, including microbial amount and diversity index, etc. Researches of Chen Hui et al. pointed out that soil microbial amount was not only motion for conversion and cycle of soil organic matter and nutrient, but also reserve place of plant available nutrient in soil. Its amount change could indicate variation of farmland ecosystem function[4-5]. Wu Fengzhi et al. thought that cultivation system had important impact on diversity index of soil microorganism[6]. Soil enzyme activity couldreflect conversion ability of soil nutrient, and is also one of important indexes evaluating soil fertility. As biological active index of soil quality evolution, soil enzyme activity has been widely accepted, and could reflect variation of soil quality under time sequence or various conditions and reasonably estimate soil quality condition at one moment[7]. Research of Dong Yan et al. thought that crop rotation was conducive to increasing numbers of bacteria and actinomyces in soil,declining fungi number and improving soil enzyme activity[8]. However, there was no report about the influences of vegetable efficient planting mode in different altitude areas of Guizhou on soil microbial flora and enzyme activity.Therefore, we analyzed change characteristics of microorganism and enzyme activity indexes under vegetable efficient planting mode,cleared its impact on soil environmental quality,and determined reasonable planting mode in different regions, which could provide theoretical basis for promoting sustainable development of vegetable.

Materials and Methods

General situation of test site

Low-altitude area Altitude of Group One of Gugua Village, Gugua Township, Sandu County is about 800 m,and annual average temperature is 17.6 ℃. Average temperature in January is more than 7.8 ℃,while it is between 26 and 27 ℃in July. Efficient planting mode is"spring Chinese cabbage-summer and autumn eggplantautumn and winter asparagus lettuce"three-maturity system in one year,while control mode is traditional "paddy-rape" two-maturity system in one year. Terrain is river valley, and vegetable planting mode is implemented for 4 years.

Middle-altitude area Altitude of Yujiashan Group, Lishan Village, Lishan Township,Fuquan City is between 600 and 1 500 m.Annual average temperature is between 13.0 and 18.3 ℃,and average temperature in January is more than 3.1 ℃. Efficient planting mode is "pepper intercropping spring Chinese cabbage-autumn and winter asparagus lettuce" three-harvest system in two seasons of one year, while control mode is pepper monoculture.Terrain is hills, and vegetable planting mode is implemented for 4 years.

High-altitude area Altitude of Group Two of Lengdi Village, Daxi Town,Dafang County is between 1 000-1 800 m.Annual average temperature is between 11.5 and 16.0 ℃, average temperature in January is more than 1.3℃. Efficient planting mode is "garlicsummer and autumn Chinese cabbage-autumn and winter wild cabbage" three-maturity system in one year, while control mode is corn monoculture.Terrain is table land,and vegetable planting mode is implemented for 4 years.

Implementation time of efficient planting mode in three sites was during 2010-2014.

Soil sampling

In different altitude t est regions, 5 representative lands were selected,and 6 sampling sites were taken from each land by using checkerboard layout, with 0-18 cm of sampling depth.After mixing evenly, 0.3 kg fresh soil sample was conserved at 0-5 ℃for measuring soil microbial number and enzyme activity.

Sample determination and data analysis

(1) Determination of soil microbial number. Bacteria culture used beef extract peptone medium; fungi culture used Martun medium; actinomyces culture used Gause’s No.1 medium.Dilution plate method was used to cultivate and count. Microbial diversity index[8]:

Here, niwas number of the i kind of species; N was number of all species in colony.

Shannon evenness index (E) =H/lnS (S was total species number in colony)

(2) Determination of soil enzyme activity. Acid phosphatase,alkaline phosphatase and catalase activities were determined by reagent box method. Urease activity was determined by indophenol blue colorimetric method, and was showed by NH3-N mg/g (37 ℃, 24 h). Concrete method referred to literature[9]. To eliminate errors of soil and reagent, each soil sample all set control without matrix and soil.Enzyme activity was calculated based on dried soil weight (105 ℃,24 h),and there were three repetitions.

(3) Detection data used statistical methods of Excel and DPS v13.01 for statistics and analysis(t test).

Results and Analysis

Soil microbial number

Seen from Table 1, soil microbial number of vegetable efficient planting mode at the same site was significantly higher than that of control. In Sandu County with low altitude,total microbial number of vegetable efficient planting mode was 1.075 8 ×1010cfu/g,which was 3.05 times of control (3.517×109cfu/g). In Fuquan City, total microbial number of vegetable efficient planting mode was 1.84 times of control. In Dafang County,total microbial number of vegetable efficient planting mode was 2.92 times of control. Seen from soil microbial composition,bacteria accounted for 99.5% of total microbial number in Sandu County, while actinomyces and fungi respectively accounted for 0.47% and 0.03% . In Fuquan City, bacteria accounted for 99.2% of total microbial number, while actinomyces and fungi accounted for 0.74% and 0.06% respectively. In Dafang County,bacteria accounted for 99.56% of total microbial number,while actinomyces and fungi accounted for 0.40%and 0.04%.Soil microbial composition of control traditional mode was similar with that of vegetable efficient planting mode.Bacteria occupied absolute advantage, while proportions of actinomyces and fungi were very small.

Via t test, total microbial number and bacteria number in low-altitude area had extremely significant difference between vegetable efficient planting mode and control (P=0.006＜0.01), and actinomyces difference reached significant level (P= 0.018＜0.05), while fungi difference was close to significant level(P=0.06).In middlealtitude area, total microbial number and bacteria number differences between vegetable efficient planting mode and control were close to significant level (P=0.076,0.079),and actinomyces difference was close to significant level(P=0.063),while fungi difference reached extremely significantlevel (P=0.002＜0.01). In high-altitude area, total microbial number and bacteria number between vegetable efficient planting mode and control had significant differences(P=0.049＜0.05),and actinomyces difference was not significant(P=0.192＞0.05),while fungi difference reached extremely significant level(P=0.002＜0.01).

Table 1 Changes of soil microbial flora in different vegetable growing regions and planting modes

Table 2 Changes of soil microbial diversity in different vegetable growing regions and planting modes

Diversity of soil microorganism

Biodiversity index is used to describe number and evenness of biological type, and could reflect species abundance in colony and distribution proportion of each type at certain degree. Seen from Table 2, Shannon evenness index, Shannon-Weaver index and Simpson index of vegetable efficient planting mode were all improved at certain degree when compared with control. Maybe vegetable efficient planting increased plant type,and caused diversity and number of material and energy flows into soil increased, which provided rich energy and carbon source for microbial propagation in rhizosphere soil, increased soil microbial diversity, and improved micro ecological environment of soil.The ratio of bacteria and fungi in soil(B/F) is an important characteristic index of soil microbial community structure[10]. B/F of vegetable efficient planting mode in each area was obviously higher than control:B/F of Sandu County was 6.69 times of control,while B/F of Fuquan City was 7.04 times, and B/F of Dafang County was 13.42 times. It illustrated that vegetable efficient planting mode provided suitable environmental condition for microbial propagation in rhizosphere soil in short term, and promoted bacteria propagation, thereby making B/F rise.

Soil enzyme activity

Soil enzyme activity is an important index showing soil fertility, quality and health[4].Seen from Table 3,phosphatase,catalase and urease activities of vegetable efficient planting mode in different cultivation areas were higher than control at varying degrees. Because available phosphorus content of efficient mode in Sandu County was high, which inhibited phosphatase activity, phosphatase activity was lower than control, while catalase and urease activities were larger than control,which were improved by 1.37 and 2.80 times respectively. Phosphatase and catalase of vegetable efficient planting mode in Fuquan City were higher than control, which were respectively improved by 1.52 and 2.41 times, while urease activity was close to control.Phosphatase, catalase and urease activities of vegetable efficient planting mode in Dafang County were all higher than control, which were improved by 1.38,1.44 and 1.51 times respectively.Via t test, urease activity between vegetable efficient planting mode and control had extremely significant difference(P=0.002＜0.01)in Sandu Coun-ty,while P values of catalase,acid and alkaline phosphatase between vegetable efficient planting mode and control were 0.130, 0.132 and 0.466 respectively, which had insignificant difference(P ＞0.05).In Fuquan City,P values of alkaline phosphatase and catalase between vegetable efficient planting mode and control were 0.031 and 0.013 respectively,which had significant difference (P＜0.05).P values of acid phosphatase and urease between vegetable efficient planting mode and control were 0.134 and 0.996 respectively,which had insignificant difference (P＞0. 05). In Dafang County, difference of catalase between vegetable efficient planting mode and control was close to significant level(P=0.058),while P values of acid and alkaline phosphatase and urease between vegetable efficient planting mode and control were 0.564,0.357 and 0.075 respectively, which had insignificant difference (P＞0.05).Under vegetable efficient planting mode, because material species and number input into soil increased, soil biochemical process was promoted,which was conducive to improving soil enzyme activity. But due to altitude influence, the improvement degree was different.

Table 3 Soil enzyme activities in different vegetables growing areas and planting modes

Conclusions and Discussion

(1)Within certain period,total microbial number and bacteria number of vegetable efficient planting mode were obviously higher than traditional mode,in which bacteria occupied absolute advantage, while proportions of actinomyces and fungi were very small.Under vegetable efficient planting mode, both microbial diversity index and B/F were higher than control. Research showed that nutrient supply condition and soil pH change had close connection with microbial flora change[5,11].The research result showed that as soil pH rise, soil actinomyces number increased, but number variations of fungi and bacteria were irregular,which needed further research.

(2) The impacts on soil catalase,urease and phosphatase activities by vegetable efficient planting mode were the same with microbial change. Soil catalase and urease activities presented significant positive correlations with soil bacteria number and total microbial number. It illustrated that soil microorganism had close relationship with enzyme activity.Soil enzyme activity was affected by its related microbial number, and the related enzyme also could form influence via indirect relationship[11-14]. Suitable nutrient species and number in soil made soil microbial biodiversity increase, and soil enzyme activity was significantly improved. However, too much nutrient input could inhibit soil enzyme activity.Available phosphorus of vegetable efficient planting mode in Sandu County was high, which caused soil phosphatase activity was lower than that of traditional mode. The application of vegetable efficient planting mode in different areas was conductive to improving soil environment quality in a given period.

[1]WANG S(王珊),LI TX(李廷轩),ZHANG XZ (张锡洲),et al.Study on changes of microbial characters in greenhouse soil(设施土壤微生物学特性变化研究)[J].Journal of Soil and Water Conservation(水土保持学报),2006,20(5):82-86.

[2]DU LF (杜连凤),ZHANG WL (张维理),WU SX (武淑霞), et al. Influence of planting age of greenhouse vegetable on soil quality degradation in Yangtse delta area (长江三角洲地区不同种植年限保护菜地土壤质量初探)[J].Plant Nutrition and Fertilizer Science (植物营养与肥料学报),2006,12(1):133-137.

[3]LI N(黎宁),LI HX(李华兴),ZHU FJ(朱风娇), et al. Relationships between soil microbial ecological characteristics and physical-chemical properties of vegetable(菜园土壤微生物生态特征与土壤理化性质的关系)[J].Chinese Journal of Applied Ecology (应用生态学报),2006,17(2):285-290.

[4]CHEN H (陈慧), HAO HR (郝慧荣),XIONG J(熊君),et al.Effects of successive cropping Rehmannia glutinosa on rhizosphere soil microbial flora and enzyme activities (地黄连作对根际微生物区系及土壤酶活性的影响)[J]. Chinese Journal of Applied Ecology(应用生态学报),2007,18(12):2755-2759.

[5]ZHANG GH(张国红),REN HZ(任华中),GAO LH (高丽红), et al. The soil microbe populations and enzyme activities in helio-greenhouse of Beijing suburbs(京郊日光温室土壤微生物状况和酶活性)[J].Scientia Agricultura Sinica(中国农业科学),2005,38(7):1447-1452.

[6]WU FZ (吴风芝),WANG XZ (王学征).Effect of monocropping and rotation on soil microbial community diversity and cucumber yield, quality under protected cultivation (设施黄瓜连作和轮作中土壤微生物群落多样性的变化及其与产量品质的关系)[J].Scientia Agricultura Sinica(中国农业科学),2007,40 (10):2274-2280.

[7]LU P(路鹏), SU YR(苏以荣), NIU Z(牛铮), et al. Soil quality assessment indicators and their spatial-temporal variability(土壤质量评价指标及其时空变异)[J]. Chinese Journal of Eco-Agriculture(中国生态农业学报),2007,15(4):190-194.

[8]DONG Y (董艳), DONG K (董坤),ZHENG Y (郑毅), et al. Soil microbial community and enzyme activities in greenhouse with different cultivation years and planting system (种植年限和种植模式对设施土壤微生物区系和酶活性的影响)[J]. Journal of Agro-Environment Science (农业环境科学学报),2009,28(3):527-532.

[9]YAO HY(姚槐应),HUANG YY(黄禺勇).Soil microbial ecology and its test technology (土壤微生物生态学及其试验技术)[M].Beijing:Science Press (北京: 科学出版社),2006:1-216.

[10]MA YH(马云华),WEI M(魏珉),WANG XF (王秀峰). Variations of microbial community and enzyme activity in helio-greenhouse continuous cropping cucumber rhizosphere (日光温室连作黄瓜根区微生物区系及酶活性的变化)[J].Chinese Journal of Applied Ecology(应用生态学报), 2004, 15 (6): 1005-1008.

[11]HAN F(韩峰),GAO X(高雪),CHEN HY(陈海燕). Enrichment difference of different types of vegetables to heavy metals (不同种类蔬菜对土壤重金属的富集差异)[J].Guizhou Agricultural Sciences (贵州农业科学), 2014, 42(6):129-132.

[12]YIN R (尹睿), ZHANG HY (张华勇),HUANG JF(黄锦法),et al.Comparison of microbiological properties between soils of rice-wheat rotation and vegetable cultivation(保护地菜田与稻麦轮作田土壤微生物学特征的比较)[J].Plant Nutrition and Fertilizing Science(植物营养与肥料学报),2004,10 (1):57-62.

[13]WANG P (王萍),HE TB (何腾兵).Area change regulation of soil characteristic of vegetable bases in Guiyang(贵阳市蔬菜基地土壤特性的区域变化规律)[J].Guizhou Agricultural Sciences(贵州农业科学),2007(35):36-39.

[14]WU FZ (吴风芝),MENG LJ (孟立君),WANG XZ(王学征).Soil enzyme activities in vegetable rotation and continuous cropping system of under shed protection(设施蔬菜轮作和连作土壤酶活性的研究)[J]. Plant Nutrition and Fertilizer Science (植物营养与肥料学报),2006,12(4):554-558.