Calcareous amendments in truffle culture: A soil nutrition hypothesis

Several statistical studies have indicated that a high concentration of active carbonate in the soil favours Tuber melanosporum fruit body production. The amount of active carbonate is significantly higher and the total carbonate is significantly lower inside than outside the T. melanosporum brûlés. These statistical patterns and other works show that T. melanosporum mycelia may acidify their immediate soil environment and solubilise carbonated fractions. Subsequently, the particular environmental conditions of brûlé soils may favour a secondary carbonate precipitation with a net increase in active carbonate which would in turn favour T. melanosporum mycelia. The greater brûlé size and fruiting are simultaneously both related to how well the fungus is growing, suggesting that the model which best explains the cause-effect of all these observations is a feedback process. Other statistical studies suggest that active carbonate favours increased fruiting of T. melanosporum as compared with Tuber aestivum, Tuber mesentericum and Tuber rufum, which has led to the use of calcareous amendments in truffle culture. We have studied the carbonated fractions of 46 soil samples from T. melanosporum plantations contaminated and uncontaminated with Tuber brumale (a serious problem in truffle culture), and it appears that the use of calcareous amendments does not serve to eradicate T. brumale from these plantations. However, we have observed the positive effect of calcareous amendments on the production of fruit bodies of both species. The similar response by T. melanosporum and T. brumale to soil active carbonate may be related to the close phylogenetic relationships between both species. Based on these findings, we propose a new soil nutrition hypothesis as a guide for research procedures in truffle soil ecology. Soils which are high in active carbonate lead to host plant chlorosis, which is a symptom of an underlying nutrient deficiency. This nutrient deficiency could lead to greater colonisation of T. melanosporum ectomycorrhizas and favour the growth of mycelia, fruit body production and brûlé development, which in turn encourages the formation of new amounts of active carbonate on the basis of the proposed feedback model.     

基于猕猴桃黄化病的土壤养分分析研究

探讨分析猕猴桃黄化原因,为农业生产提供理论支撑。2019年果实采收后,在眉县选取5个黄化猕猴桃园、5个正常猕猴桃园,采集土样,带回实验室处理后进行养分测定分析。该黄化猕猴桃园土壤pH值过高,有机质含量偏低,整体土壤地力瘠薄。因此,调节土壤pH,增施有机肥,平衡施肥是防治猕猴桃黄化病的基础措施。     

美味猕猴桃叶片有效铁含量与黄叶病相关性研究

通过对关中渭河流域42个猕猴桃园60个美味猕猴桃叶样(其中正常叶30个,黄叶30个)中铁含量的测定分析,认为美味猕猴桃叶片中所含有效铁及全铁间无相关性(绿叶的相关系数r=0.28010;黄叶的相关系数r=0.14607).在正常叶中,有效铁含量E=67.13±27.63 (mg/kg),全铁含量T=164.75±52.10 (mg/kg);黄叶中有效铁含量E=55.02±19.68 (mg/kg),全铁含量T=166.13±50.52 (mg/kg).t检验证明无论有效铁(t=3.70)、全铁/有效铁(t=3.98)还是有效铁/全铁(t=2.85),黄叶和绿叶间均差异显著(t0.01=2.74).唯有全铁含量差异不显著(t=0.166).     

Fe-EDDHA矫治桃叶失绿效果及对叶元素含量的影响

在西安北郊石灰性桃园土壤上施用不同剂量的Fe-EDDHA制剂中叶绿灵，结果表明，萌芽时株施30-45g叶绿灵对矫治桃叶失绿黄化有明显效果，可一直维持到当年落叶，同黄化植株相比，叶片叶绿素含量增加391．7％－71．8％，果实品质明显提高，还改善了叶片营养元素的平衡比例。     

摘心及6－苄基腺嘌呤处理对桑叶缺铁性黄化早衰的延缓作用

当生长在石灰性土壤上的桑树新梢行将缺铁性黄化时，进行叶面追施６－苄基腺嘌呤（６－ＢＡ）和摘心处理。处理枝的早衰症状明显延缓，叶形增大，叶色转绿；各叶位的叶绿素、蛋白质及ＳＯＤ、ＣＡＴ、ＰＯＸ含量或活性水平不同程度地增加；膜脂过氧化作用产物ＭＤＡ含量明显降低，起了延缓早衰的作用。延缓作用摘心比６－ＢＡ处理有效。     

The coat protein of <Emphasis Type="Italic">Tomato mosaic virus</Emphasis> L<Subscript>11</Subscript>Y is associated with virus-induced chlorosis on infected tobacco plants

The L₁₁Y strain of Tomato mosaic virus (ToMV) causes severe chlorosis on infected tobacco leaves. Sequencing analysis for the genome showed that L₁₁Y contained multiple nucleotide changes and that some led to amino acid substitutions, when compared with that of the common L strain of ToMV. The chimeric virus, which has the CP of L₁₁Y in the context of the L strain RNA genome, caused severe chlorosis on infected tobacco plants, suggesting that the CP of L₁₁Y containing three amino acid changes (E33S, A86T and E97K) was the determinant of the chlorosis. Two of these amino acid changes (A86T and E97K) were associated with the induction of chlorosis when present together in the CP. Severe destruction and deformation of chloroplasts and the formation of discrete dark-staining materials adjacent to chloroplasts were observed with electron microscopy in L₁₁Y-infected plants. Fewer virus particles accumulated in the cytoplasm of L₁₁Y-infected plant cells. The level of accumulation of CP subgenomic RNA and CP in the infected protoplasts was similar between L and L₁₁Y. Fewer virus particles accumulated in L₁₁Y-infected protoplasts, and many of them were shorter-than-full-length. The nucleotide sequence data reported is available in DDBJ/EMBL/GenBank databases as accession AB355139.     

Cloning of a specific DNA region of white top pathogen of pea and its detection by polymerase chain reaction

White top strain (WT strain) of Pseudomonas syringae pv. pisi (Ppi) is a variant strain causing white top disease of peas. The WT strain is distinguishable from common Ppi strains only by symptom expression chlorosis and whitening of apical shoots. To develop a specific detection method for the WT strain, we cloned a specific DNA region of the WT strain using transposon tagging. Five mutants defective in white top symptom expression were obtained. A part of the Tn5-flanking region was cloned and labeled as a hybridization probe. One clone, pAY3, gave two signal bands, one of which was detected from the genomic DNA of all the WT and the common Ppi strains; another was specific to WT strains. A restriction map of pAY3 showed that it contains two BamHI fragments; one is 5.0kb in length involving a part of Tn5, and the other is 1.5kb, did not carry Tn5, and may have been accidentally ligated into pAY3. The 1.5-kb band was subcloned as pAY13 and was used as a probe. It hybridized specifically to WT strains. These results suggested that the WT strains have a specific DNA region and that part of the region was successfully cloned. Sequence analysis of pAY13 showed that it is similar to part of nonribosomal peptide synthetases (NRPSs) genes. The deduced amino acid sequence of pAY13 suggested the existence of eight conserved motifs of NRPSs. WT strain-specific PCR primers, PS1 and PS2, were designed from the DNA sequence. These primers gave a specific amplification product of 981bp from both the genomic DNA and a direct cell preparation of WT strains. No specific amplicon was produced from Ppi strains that caused only water-soaked lesions or from strains of other P. syringae pathovars. A specific amplicon was not produced from four strains of the pea pathogen: P. marginalis pv. marginalis, P. viridiflava, Erwinia carotovora ssp. carotovora, Xanthomonas campestris pv. pisi. Using the primers, WT strain was detected from water-soaked lesions and green and white tissues without water soaking.The sequence reported in this paper has been deposited in the DDBJ database under accession no. AB117755     

铁肥品种和施肥方式对黄化苹果树复绿和铁含量的影响

铁胁迫致苹果黄叶时,对根系输铁液能在较短时间内提高叶片叶绿素和铁的含量,从而达到复绿的效果。在Ｆｅ Ｃｉｔｒｉｃ ａｃｉｄ、Ｆｅ ＥＤＴＡ 和Ｆｅ Ｎ 三种铁肥中,Ｆｅ Ｎ 是适宜根系输液的铁肥品种,主干强力高压注射铁肥复绿较慢,叶面喷布效果不显著。     

根际操作施肥矫正苹果缺铁黄叶病的研究

采用根部输硫酸亚铁、柠檬酸铁、ＥＤＴＡ铁、根际施硫酸亚铁和自制专用肥的方法对苹果黄叶病进行矫正。结果表明：各种补铁措施均可提高叶片中活性铁及叶绿素含量,使黄叶病树病梢率和失绿级数下降。与对照比较,根际施硫酸亚铁效果差。各输液处理间没有明显差异,表现叶片复绿较快,但肥效持续时间短,操作困难,输用浓度为０．０２７ｍｏｌ·Ｌ＾－１铁液,果树幼嫩叶片有轻度卷曲的受害症状。自制专用肥效果最好,经一年春、秋２     

玉米矮花叶病抗性鉴定的研究

利用严重的玉米矮花叶病区和人工接种诱发自然传播的方法,鉴定了我国主要玉米自交系及杂交种220个,并将其抗病程度分为高抗、中抗、耐病、中耐及感病五个等级。发现抗病自交系16种,其中获白、二南24、黄早四的抗病力强,配合力好,是我国目前最优抗源。全国现已应用此抗源育成新的抗耐病杂交种20个以上,在生产上收到明显的经济效益。