Influence of urea on the cherry leaf spot pathogen, Blumeriella jaapii, and on microorganisms in decomposing cherry leaves
Influence of urea on the cherry leaf spot pathogen, Blumeriella jaapii, and on microorganisms in decomposing cherry leaves
复制标题
DOI：
10.1016/j.soilbio.2006.04.027
复制
发表时间：
2006-09
影响因子：
9.7
通讯作者：
H. Green;M. Bengtsson;X. Duval;H. Pedersen;J. Hockenhull;J. Larsen
中科院分区：
文献类型：
--
作者：
H. Green;M. Bengtsson;X. Duval;H. Pedersen;J. Hockenhull;J. Larsen
生长室和果园进行了实验，以澄清樱桃叶斑病菌，Blumeriella jaapii，和落叶中的微生物的响应，以两个水平的尿素（2.5%或5%）后，落叶酸樱桃叶。总体而言，施用尿素减少了B的发育。在春季，通过定量PTA-ELISA在落叶和孢子计数中测量jaapii的生物量，并增加了总体微生物生物量（用生物标志物磷脂脂肪酸（PLFA）测量）和真菌活性（评估为β-N-乙酰氨基葡萄糖苷酶活性）。除B外，施用尿素后凋落物中所有微生物类群的生物量均立即增加。jaapii和含有生物标志物PLFA cyclo 17：0的革兰氏阴性细菌的处理，在氨和pH水平稳定至与对照叶相似的水平后约10天继续。施用2.5%的尿素增加了大多数腐食性微生物的生物量，加速凋落物分解的程度高于施用5%的尿素，在处理后的第一周内，5%的尿素水平抑制了总微生物生物量。这可能归因于氨毒性，因为施用后第一周，5%尿素导致的氨升高明显高于2.5%尿素。从那时起，在2.5%和5%的治疗真菌和革兰氏阳性菌群受益于降低C：N比，增加其活动约2倍相比，水处理的控制。抑制B。jaapii与尿素分解期一致，其中在处理的叶片中测量到氨和叶片pH水平升高。这一时期持续了大约10天，之后B.处理叶片中的JAAPII继续以缓慢但比未处理叶片中更快的速率降低。我们的研究结果表明，尿素的应用引起了叶片pH值和氨水平的升高，这与凋落物分解的加速一起，对B的腐殖生长产生不利影响。jaapii，导致第二年春天子囊孢子和冬分生孢子的产生减少。
Growth chamber and orchard experiments were carried out to clarify the response of the cherry leaf spot pathogen, Blumeriella jaapii, and microorganisms in the leaf litter to two levels of urea (2.5% or 5%) applied post leaf fall to sour cherry leaves. In general, urea application reduced the development of B. jaapii measured as biomass by quantitative PTA-ELISA in the leaf litter and spore counting in the spring and increased the overall microbial biomass (measured with biomarker phospholipid fatty acids (PLFAs)) and fungal activity (assessed as β-N-acetylglucosaminidase activity). The biomass increase of all groups of microorganisms in the litter generally began immediately after application of urea and, with the notable excepts of B. jaapii and Gram-negative bacteria containing the biomarker PLFA cyclo17:0, continued after the ammonia and pH levels had stabilized to levels similar to the control leaves approximately 10 days later. Application of 2.5% urea increased the biomass of most groups of saprotrophic microorganisms and accelerated litter decomposition to a higher extent than application of 5% urea and during the first week after treatment applications the 5% urea level inhibited the total microbial biomass. This may be ascribed to ammonia toxicity as 5% urea resulted in a markedly higher ammonia elevation than 2.5% urea, the first week after application. From then onwards in both the 2.5% and 5% treatments the fungal and Gram-positive communities benefited from a lowered C:N ratio, increasing their activities approximately 2 times compared to a water-treated control. Inhibition of B. jaapii coincided with the period of urea breakdown in which elevated levels of ammonia and leaf pH were measured in the treated leaves. This period lasted for approximately 10 days after which the biomass of B. jaapii in the treated leaves continued to decrease at a slow but faster rate than in the untreated leaves. Our results indicate that the urea application caused an elevation in leaf pH and ammonia levels, which together with an acceleration in litter decomposition, adversely affected the saprotrophic growth of B. jaapii, leading to reduced production of ascospores and winter-conidia the following spring.