植物营养与肥料学报
植物營養與肥料學報
식물영양여비료학보
PLANT NUTRITION AND FERTILIZER SCIENCE
2014年
4期
870-876
,共7页
无菌培养%有机磷%磷酸单酯酶%磷酸双酯酶%根际pH
無菌培養%有機燐%燐痠單酯酶%燐痠雙酯酶%根際pH
무균배양%유궤린%린산단지매%린산쌍지매%근제pH
axenic cultivation%organic phosphorus%phosphomonoesterase%phosphodiesterase%rhizosphere pH
【目的】土壤有机磷在土壤全磷中占有很大比重，是植物潜在的有效磷源，但必须通过磷酸酶的水解作用释放出无机磷才能被植物利用。土壤中有机磷的主要形式为磷酸单酯和磷酸双酯。本研究中，我们探讨了无菌条件下不同形态的氮源引起的根际pH变化如何影响植物对这两种有机磷的活化利用。【方法】采用琼脂无菌培养体系种植玉米，向玉米植株供应两种形态的氮源和磷源，氮源为硝态氮和铵态氮，磷源为植酸钙和卵磷脂，植酸钙属于磷酸单酯盐，卵磷脂属于磷酸双酯盐。不同的供氮形态会导致根际pH变化，进而研究根际pH变化对磷酸单酯盐和磷酸双酯盐的活化利用所产生的影响。【结果】当给玉米供应铵态氮时，根际pH从5.5降至4.0；供应硝态氮时，根际pH升至6.6。测定玉米根际的琼脂中根系分泌的磷酸单酯酶和磷酸双酯酶活性发现，磷酸单酯酶活性在pH 6.07.0之间最高，磷酸双酯酶活性在pH 7.08.0之间达到最高。无论以植酸钙还是卵磷脂为有机磷源，相对于铵态氮处理，硝态氮处理能够使根际保持较高的磷酸单酯酶或磷酸双酯酶活性。有机磷的水解过程由磷酸酶活性和底物有效性两个因素控制，而植酸钙的水解受根际pH影响很大，在一定pH范围内，植酸钙的溶解度随根际pH值降低而升高，有效态磷浓度的增加，使得磷酸酶的底物有效性提高。在供应铵态氮时，根际pH值降低，玉米对植酸钙的利用效率高于硝态氮处理，尽管供硝态氮时磷酸单酯酶活性更高。同时，在供应铵态氮条件下，植株对植酸钙的利用率要显著高于卵磷脂，原因在于虽然磷酸双酯酶和磷酸单酯酶活性较低，由于植酸钙的溶解度较大，它的底物有效性更高。因此，植酸钙处理中植株的磷含量更高。相反，在供应硝态氮时，植酸钙溶解度减小而两种磷酸酶活性较高，卵磷脂处理中植株的磷含量更高。【结论】土壤中有机磷的水解过程由磷酸酶活性和有机磷底物有效性两个因素控制，酶活性与根际pH密切相关。本研究说明土壤有机磷的活化必须首先转化为溶解于水溶液中的状态，才能作为磷酸酶的底物被催化水解。我国长期施用化肥导致北方土壤大范围酸化，这种酸化无疑对土壤固有或随有机物料进入农田的有机磷的活化利用是具有重要贡献的，应该在北方土壤养分管理中应加以考虑。
【目的】土壤有機燐在土壤全燐中佔有很大比重，是植物潛在的有效燐源，但必鬚通過燐痠酶的水解作用釋放齣無機燐纔能被植物利用。土壤中有機燐的主要形式為燐痠單酯和燐痠雙酯。本研究中，我們探討瞭無菌條件下不同形態的氮源引起的根際pH變化如何影響植物對這兩種有機燐的活化利用。【方法】採用瓊脂無菌培養體繫種植玉米，嚮玉米植株供應兩種形態的氮源和燐源，氮源為硝態氮和銨態氮，燐源為植痠鈣和卵燐脂，植痠鈣屬于燐痠單酯鹽，卵燐脂屬于燐痠雙酯鹽。不同的供氮形態會導緻根際pH變化，進而研究根際pH變化對燐痠單酯鹽和燐痠雙酯鹽的活化利用所產生的影響。【結果】噹給玉米供應銨態氮時，根際pH從5.5降至4.0；供應硝態氮時，根際pH升至6.6。測定玉米根際的瓊脂中根繫分泌的燐痠單酯酶和燐痠雙酯酶活性髮現，燐痠單酯酶活性在pH 6.07.0之間最高，燐痠雙酯酶活性在pH 7.08.0之間達到最高。無論以植痠鈣還是卵燐脂為有機燐源，相對于銨態氮處理，硝態氮處理能夠使根際保持較高的燐痠單酯酶或燐痠雙酯酶活性。有機燐的水解過程由燐痠酶活性和底物有效性兩箇因素控製，而植痠鈣的水解受根際pH影響很大，在一定pH範圍內，植痠鈣的溶解度隨根際pH值降低而升高，有效態燐濃度的增加，使得燐痠酶的底物有效性提高。在供應銨態氮時，根際pH值降低，玉米對植痠鈣的利用效率高于硝態氮處理，儘管供硝態氮時燐痠單酯酶活性更高。同時，在供應銨態氮條件下，植株對植痠鈣的利用率要顯著高于卵燐脂，原因在于雖然燐痠雙酯酶和燐痠單酯酶活性較低，由于植痠鈣的溶解度較大，它的底物有效性更高。因此，植痠鈣處理中植株的燐含量更高。相反，在供應硝態氮時，植痠鈣溶解度減小而兩種燐痠酶活性較高，卵燐脂處理中植株的燐含量更高。【結論】土壤中有機燐的水解過程由燐痠酶活性和有機燐底物有效性兩箇因素控製，酶活性與根際pH密切相關。本研究說明土壤有機燐的活化必鬚首先轉化為溶解于水溶液中的狀態，纔能作為燐痠酶的底物被催化水解。我國長期施用化肥導緻北方土壤大範圍痠化，這種痠化無疑對土壤固有或隨有機物料進入農田的有機燐的活化利用是具有重要貢獻的，應該在北方土壤養分管理中應加以攷慮。
【목적】토양유궤린재토양전린중점유흔대비중，시식물잠재적유효린원，단필수통과린산매적수해작용석방출무궤린재능피식물이용。토양중유궤린적주요형식위린산단지화린산쌍지。본연구중，아문탐토료무균조건하불동형태적담원인기적근제pH변화여하영향식물대저량충유궤린적활화이용。【방법】채용경지무균배양체계충식옥미，향옥미식주공응량충형태적담원화린원，담원위초태담화안태담，린원위식산개화란린지，식산개속우린산단지염，란린지속우린산쌍지염。불동적공담형태회도치근제pH변화，진이연구근제pH변화대린산단지염화린산쌍지염적활화이용소산생적영향。【결과】당급옥미공응안태담시，근제pH종5.5강지4.0；공응초태담시，근제pH승지6.6。측정옥미근제적경지중근계분비적린산단지매화린산쌍지매활성발현，린산단지매활성재pH 6.07.0지간최고，린산쌍지매활성재pH 7.08.0지간체도최고。무론이식산개환시란린지위유궤린원，상대우안태담처리，초태담처리능구사근제보지교고적린산단지매혹린산쌍지매활성。유궤린적수해과정유린산매활성화저물유효성량개인소공제，이식산개적수해수근제pH영향흔대，재일정pH범위내，식산개적용해도수근제pH치강저이승고，유효태린농도적증가，사득린산매적저물유효성제고。재공응안태담시，근제pH치강저，옥미대식산개적이용효솔고우초태담처리，진관공초태담시린산단지매활성경고。동시，재공응안태담조건하，식주대식산개적이용솔요현저고우란린지，원인재우수연린산쌍지매화린산단지매활성교저，유우식산개적용해도교대，타적저물유효성경고。인차，식산개처리중식주적린함량경고。상반，재공응초태담시，식산개용해도감소이량충린산매활성교고，란린지처리중식주적린함량경고。【결론】토양중유궤린적수해과정유린산매활성화유궤린저물유효성량개인소공제，매활성여근제pH밀절상관。본연구설명토양유궤린적활화필수수선전화위용해우수용액중적상태，재능작위린산매적저물피최화수해。아국장기시용화비도치북방토양대범위산화，저충산화무의대토양고유혹수유궤물료진입농전적유궤린적활화이용시구유중요공헌적，응해재북방토양양분관리중응가이고필。
[Objectives]Soil organic phosphorus is accounted for a large proportion in total soil phosphorus, and is a kind of potential available phosphorus. Hydrolyzing by phosphatase is the only way obtaining phosphorus for the plants. There are mainly two forms of organic phosphorus in the soil, one is phosphomonoester, and the other one is phosphodiester. An axenic agar cultivation in Petri dish was conducted to study effects of pH on phosphomonoesterase or phosphodiesterase utilization in maize rhizosphere. [Methods]The method of an axenic agar in Petri dish was used in this experiment. Two kinds of nitrogen forms ( NO3- and NH4+) and two kinds of organic phosphorus forms ( phytin: phosphomonoester and lecithin: phosphodiester ) were supplied in the maize rhizosphere. Different nitrogen forms will lead to the pH changes in rhizosphere, which can be used to evaluate the effects of pH on phosphomonoesterase or phosphodiesterase utilization in maize rhizosphere. [Results]When the NH4+ form was supplied, rhizosphere pH was decreased from 5. 5 to 4. 0, while nitrogen was supplied in the NO3-form, rhizosphere pH was increased to 6. 6. Activity analysis showed that activity of phosphomonoesterase secreted by maize roots in the axenic agar is highest when pH is 6. 0-7. 0 , and phosphodiesterase activity is highest when pH is 7. 0-8. 0. Whether phytin or lecithin was supplied, phosphomonoesterase or phosphodiesterase activity in the NO3- treatment was higher than that in the NH4+ treatment. For the phosphorus was derived from organic phosphates of maize in each treatment, the hydrolyzation of organic phosphorus is controlled by phosphatase activity and availability of substrate. The hydrolysis of phytin was strongly influenced by rhizosphere pH, especially in the acid condition, the solubility of phytin increased and then the availability of phosphatase substrate increased, and the concentration of the organic phosphorus became higher than before, and led to that the maize could absorb more phosphorus. The maize absorbed more phosphorus from phytin in the NH4+ treatment than that from in the NO3-treatment, although the phosphatase activity was not higher. In a similar way, when the NH4+ form nitrogen was supplied , the phosphorus use efficiency by the maize in the phytin treatment was higher significantly than that in the lecithin treatment, because the solubility of phytin was higher under this condition. Although phosphomonoesterase or phosphodiesterase activity was lower, the effectiveness of phosphatase substrate was higher, therefore, the maize absorbed more phosphorus. In the contrast, when NO3- was supplied, the solubility of phytin decreased and the activity of two kinds of phosphatase was increased, and led to that more phosphorus absorbed by maize in the lecithin treatment was higher than that in the phytin treatment. [Conclusions]Hydrolyzation of organic phosphorus is influenced by phosphatase activity and substrate availablilty, and the changes of soil enzyme activity is closely related to pH environment. Activation of organic phosphorus in the soils must be transformed into the dissoluble form, which is a substrate of phosphatase and is hydrolyzed. Fertilizer application for a long time in China can result in acidification in large areas, and this acidification can be helpful to activation of organic phosphorus in soils and/or in organic residues, indicating that the practices of soil acidification should be scientifically considered in soil nutrient manegement in northern China.
