讀書報告6BT棉花對根際土壤酶活性和土壤微生物的影響

1、effect of bt cotton on enzymes activity and microorganisms in rhizosphere bt棉花對根際土壤酶活性和土壤微生物的影響 usha mina 、anita chaudhary、anju kamra journal of agricultural science（2011） page 2 outline 1 introduction 2 materials and methods 2.1 field preparation and cultural practices 2.2 soil sampling 2.3 dehydro

2、genase 、alkaline phosphatase 、urease 、 nitrate reductase activity 2.4 nematodes（線蟲）、collembola（彈尾目） and ants 3 results and discussion page 3 1 introduction n in india nine million hectares (m ha) area was under cotton cultivation and it is one fourth of the global area under cotton cultivation . bac

3、illus thuringiensis (bt) cotton was introduced in india in 2002. following its success, during the last 7 years (2002-2008), the area under bt cotton has increased by 7.6 m ha from 0.029 m ha . 在印度棉花的種植面積達九百萬公頃，占全球棉花種植面積的四分之一。印 度在2002年引進蘇云金芽孢桿菌(bt)棉。在過去的7年(2002 - 2008) ，種植面 積從29萬公頃增加到760萬公頃。 james,2

4、008 page 4 n although there are diverse benefits of bt cotton, public concern also exist because both in vitro and in vivo studies on bt cotton showed that bt toxin produced in leaves, stems and roots of bt cotton plants is introduced in soil. 通過對bt棉體外和體內(nèi)的研究表明，bt棉花在葉片、莖和根部產(chǎn)生bt 毒素并釋放到土壤中 。 n bt-toxin

5、 from bt cotton plants introduced into the soil through two pathways, i.e., biomass incorporation and root exudates . bt毒素通過兩條途徑從bt棉花植物體釋放到土壤，例如，生物量合成和 根分泌物 。 saxena and stotzky 2001 mina et al., 2008 liu 2009 page 5 n bt toxin released in soil get adsorbed or bound on clay particles, humic componen

6、ts, or organic mineral complexes and then be protected against degradation by soil microorganisms (tapp et al., 1995) . 釋放到土壤中的bt毒素被粘土顆粒、腐植酸或有機礦物復合體吸附或束 縛, 防止其被土壤微生物降解。 n continuous growing of bt crops on same location enhance its existing levels to a certain concentration that might affect the comp

7、osition and activity of soil microbial communities (donegan and seidler 1999; stotzky 2004; wei et al., 2006) and the soil biochemical. 在同一地點連續(xù)種植bt作物其濃度就會增加，當達到某一定濃度時就有可能 影響土壤微生物群落的組分和活動以及土壤的生物化學特性。 page 6 n some studies indicate that bt cotton has no negative effects on soil flora and fauna and may

8、 even have beneficial effects (saxena and stotzky 2001; sarkar et al., 2009)， while some have reported adverse effects (cui and xia 2000; tan et al.,2002). 一些研究表明bt棉花不會對土壤植物和動物造成負面影響,甚至可能產(chǎn)生有 益作用，同時也有一些不良影響的報導。 n therefore, we have studied the effects of bt cotton (var. mech 162) on activity of soil

9、enzymes and microorganisms at indian agriculture research institute farms, new delhi, india. an evaluation of the ecological risks of bt cotton was made on the basis of changes in enzymes activity and number of nematodes, collembola and ants as compared to non bt cotton in the respective rhizosphere

10、s. 因此，我們研究印度農(nóng)業(yè)研究所農(nóng)場、新德里、印度的bt棉花對土壤酶活性 和土壤微生物的影響。針對bt棉花和非bt棉花的植物根際酶活性變化量和線 蟲、彈尾目昆蟲和螞蟻的數(shù)量變化進行生態(tài)風險評價。 page 7 2 materials and methods n 2.1 field preparation and cultural practices field experiments were conducted at the research farm of the indian agricultural research institute, new delhi,india. 田間試驗布

11、置在印度的農(nóng)業(yè)研究所的農(nóng)場、新德里、印度。 experiments were conducted for three consecutive years (2004, 2005 and 2006) in a large plot(450 m2) where bt and non bt cotton had ever planted. this plot was subdivided into 24 subplots (3.75m x 5m). 在常年種植bt和非bt棉花的土壤上進行了三年(04、05、06年)的 連續(xù)試驗，總面積為450m2，分為24個小區(qū)(3.75m5m)。 page 8 n

12、 treated :seeds of non bt cotton and bt cotton. n distance between row to row and plant to plant :60 cm and 45 cm respectively. n buffer zone : a 6 m also established surrounding the main plot. n recommended dose of npk fertilizer :660 g n as urea, 250 g p as ssp, 350 g k as mop n applied time:phosp

13、horus and potash was applied at time of sowing, whereas nitrogen was given in split dose, half at the time of thinning and other half at flowering stage. n irrigate time:first irrigation to cotton was given one week after sowing and subsequent irrigations at an interval of two weeks. n harvest time:

14、in the first week of december in all the three years page 9 page 10 2.2 soil sampling n soil samples from the rhizosphere of bt cotton and non bt cotton plants were collected at regular interval (30days interval, coinciding with different growth stage of cotton) since the date of sowings till harves

15、ting in all the three years. bt棉花和非bt棉花根際土壤樣品在整個三年內(nèi)都是自播種之日起有規(guī)律間隔采 集的(30天間隔,正好與棉花不同生育期相符合)。 page 11 n 2.3 dehydrogenase 、alkaline phosphatase 、urease 、 nitrate reductase activity enzymewavelength dehydrogenase492nm alkaline phosphatase400nm urease527nm nitrate reductase activity520nm n measured using

16、 uvvis spectrophotometer (uv-1201, shimadzu corp, japan)紫外可見光譜分光光度計 page 12 n 2.4 nematodes（線蟲）、collembola（彈尾目） and ants nematodes:從水里提取后用立體解剖顯微鏡計數(shù) collembola and ants：用干漏斗提取后用立體解剖顯微鏡計數(shù) page 13 3. results and discussion page 14 page 15 n on average dehydrogenase, alkaline phosphatase, nitrate reduct

17、aase and urease enzymes activity was high in bt cotton rhizosphere as compared to non bt rhizosphere. n on comparing enzymes activity for the interaction of crop variety (bt and non bt trait) over a monthly period, activity of dehydrogenase and urease enzymes were non significant and activity of pho

18、sphates and nitrate reductase enzymes were significant. 總體來講，與非bt棉花根際土壤相比，bt棉花根際土壤的脫氫酶、堿性磷酸 酶、硝酸還原酶和脲酶活性較高。 在比較作物品種(bt和非bt特質(zhì))相互作用的酶活性超過一個月后，脫氫酶和 脲酶活性都沒有較大變化，而磷酸酶和硝酸還原酶有顯著的變化。 page 16 n figure 1. variations in activity of (a) dehydrogenase (b) alkaline phosphatase (c) nitrate reductase and (d)urease

19、enzymes at different growth stages in bt and non bt cotton rhizosphere page 17 n except dehydrogenase enzyme, differences in activity of alkaline phosphatase, nitrate reductase and urease enzymes between bt and non bt plants rhizosphere were statistically non significant. over the crop growth period

20、 (of 150 days) the activity of phosphatase, nitrate reductaase and urease enzymes activity was high in the rhizosphere at early vegetative and flowering stage,whereas activity of dehydrogenase enzyme was high at boll formation stage .activity of all the four enzymes declined at crop harvesting stage

21、 . 除了脫氫酶以外，堿性磷酸酶、硝酸還原酶和脲酶活性在bt和非bt棉花根 際之間的差異不顯著。作物生長期間(150天)，磷酸酶、硝酸還原酶和脲酶 活性在早期營養(yǎng)生長和開花階段較高，脫氫酶活性則在鈴形成階段較高 。 四種酶在作物收獲階段活性都會降低。 page 18 n study demonstrated enhanced phosphatase, nitrate reductase and urease activity in the rhizosphere of bt cotton, but most of the time differences in enzymes activity

22、 between bt and non-bt cotton rhizosphere were non significant. 有研究證實bt棉花根際土壤的磷酸酶、硝酸還原酶和脲酶活性增強，但大部 分時間里，bt棉和非 bt 棉根際酶活性之間的差異并不顯著。 n in present study variation in dehydrogenase enzyme activity between bt and non-bt cotton rhizosphere was significant (p0.05) and activity of dehydrogenase enzyme was hi

23、gh in bt cotton rhizosphere. 目前的研究表明，非bt棉和bt棉花之間根際土壤脫氫酶活性變化是顯著的(p 0.05)，bt棉花根際土壤的脫氫酶酶活性高于非bt棉。 page 19 n the enhancement in activity of dehydrogenase in bt cotton rhizosphere may be due to altered composition of its root exudates. root exudates have a profound qualitative and quantitative effect on

24、the rhizospheric microorganisms. bt棉花根際土壤的脫氫酶活性增強可能是由于其根際分泌物成分的變化。根 際分泌物對于微生物的組成起著重大的定性和定量的作用。 schenck, 1976 page 20 table 4. number of nematodes, collembola, ants in bt and non bt cotton rhizosphere page 21 n significant differences (p0.05) were observed in the number of nematodes, collembola and a

25、nts between the bt and non bt cotton rhizosphere (table 4). number of nematodes, collembola and ants were more in bt plants rhizosphere as compared to non bt plants rhizospere. number of nematodes, collembola and ants were highest in bt and non bt cotton rhizosphere at flowering stage. 研究發(fā)現(xiàn)bt棉花和非bt棉

26、花根際的線蟲、彈尾目昆蟲及螞蟻數(shù)量（表4)有顯 著差異(p 0.05)。與非bt棉花相比，bt棉花根際的線蟲、彈尾目昆蟲和螞 蟻數(shù)量更多。bt和非bt棉花這三者的數(shù)量均在開花階段達到最高。 page 22 n temporal variation in number of nematodes, collembola and ants is a complicating factor in impact assessment of bt transgenic cotton, because the impact of the genetic modification may be transie

27、nt and minor compared to the variation caused by soil condition and growth stage of crop. 線蟲、彈尾目昆蟲和螞蟻數(shù)量的時間變化在bt轉(zhuǎn)基因棉影響評價中是一個 復雜因素，因為與土壤條件和作物的生長階段帶來的變化相比，基因轉(zhuǎn)變的 影響可能是短暫的、微小的 。 n however these results should be considered as preliminary, as nematodes, collembola and ants are mobile and slight change in their niche environment may affect their mobility