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首页> 外文会议>STI/PUB/1285; Consultants Meeting on Management Practices for Improving Sustainable Crop Production in Tropical Acid Soils; 19990501-03; Vienna(AT) >IDENTIFICATION AND CHARACTERIZATION OF ALUMINIUM-RESISTANT, PHOSPHORUS-EFFICIENT PLANT GENOTYPES ADAPTED TO TROPICAL ACID SOILS
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IDENTIFICATION AND CHARACTERIZATION OF ALUMINIUM-RESISTANT, PHOSPHORUS-EFFICIENT PLANT GENOTYPES ADAPTED TO TROPICAL ACID SOILS

机译：适应于铝酸土壤的耐铝磷肥植物基因型的鉴定与鉴定

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In most tropical acid soils, aluminium (Al) toxicity and phosphorus (P) deficiency are the most important factors limiting plant growth and crop yields. One of the key elements of sustainable cropping systems on these soils is the integration of crops and/or crop cultivars with high Al resistance and P efficiency. Experimental activities on enhancing plant P efficiency concentrated on the characterization of the P mobilising capacity of different leguminous grain and cover crops, and their effect on P availability to less P-efficient cereals grown in mixed culture and in rotation. Fractionation of P in the rhizosphere soil revealed the capacity of some legumes to better use P from sparingly soluble soil P fractions than maize. Field experiments conducted on 2 sites in the Northern Guinea Savannah of Nigeria and accompanying green-house pot-experiments revealed a positive rotational effect of P-efficient cover crops on maize growth and grain yield with and without return of crop residues. This could be attributed to a better P supply to maize especially on the strongly P-fixing soil. Experimental work related to Al toxicity and resistance focussed on the development of a selection technique for Al resistance and thus adaptation to acid soils, the genetics of Al resistance in maize, the role of cell-wall and plasma-membrane characteristics, and organic acid metabolism in Al resistance in maize, and the characterisation of differences in Al resistance in common bean. A 15x15 cultivars diallel was evaluated under field conditions and in hydroponics for Al-induced callose formation. The statistical analysis clearly showed that the General Combining Ability (GCA) rather than the Specific Combining Ability (SCA) is of major importance for Al resistance. Al-induced callose formation was negatively correlated to yields on acid soils. This screening technique proved to be a powerful tool in the identification of germplasm with high combining ability for adaptation to acid Al-toxic soils. Among the cell-wall properties the pectin content and its degree of methylation appeared to be of particular importance as indicated by a positive correlation between Al injury of root apices and pectin content and its degree of methylation. Silicon-induced amelioration of Al toxicity could be related to an in-planta effect. Al-treated plants accumulated higher amounts of Si in the root apical cell walls than non Al-treated plants, thus reducing the amount of the readily exchangeable Al in the cell walls. The importance of plasma-membrane properties for Al resistance was indicated by experiments with A8-sphingolipid desaturase-transformed maize plants which were more affected by Al than the wild-type, and differences in the degree of desaturation of fatty acids between a resistant and a sensitive maize cultivar. The changes were small, but experiments with yeast transformed with a 9-acyl desaturase showed that a small change in the degree of desaturation led to a very strong increase in Al resistance.
机译：在大多数热带酸性土壤中，铝（Al）毒性和磷（P）缺乏是限制植物生长和作物产量的最重要因素。在这些土壤上可持续种植系统的关键要素之一是高抗铝和高磷效率的农作物和/或农作物品种的整合。提高植物磷效率的实验活动集中于表征不同豆科作物和覆盖作物的磷动员能力，以及它们对混合培养和轮作中生长的磷效率较低的谷物的磷有效性的影响。根际土壤中的P分级显示出一些豆科植物比玉米更能利用难溶性土壤P馏分中的P的能力。在尼日利亚北部几内亚萨凡纳州的2个地点进行的田间试验以及伴随的温室盆栽试验表明，磷肥覆盖作物对玉米生长和谷物产量的正向轮换效应，有或没有残留农作物。这可能归因于向玉米提供更好的磷供应，尤其是在固氮能力强的土壤上。与铝毒性和抗性有关的实验工作集中在开发一种铝抗性选择技术（从而适应酸性土壤），玉米中铝抗性的遗传学，细胞壁和质膜特性的作用以及有机酸代谢方面玉米抗铝性的研究，以及普通豆抗铝性差异的表征。在田间条件下和在水培法中评估了15x15的品种Dialel，以测定Al诱导的call形成。统计分析清楚地表明，一般结合能力（GCA）而非特异性结合能力（SCA）对耐铝性具有重要意义。铝诱导的ose质形成与酸性土壤上的产量负相关。事实证明，这种筛选技术是鉴定种质的有力工具，具有对酸性铝毒土壤的高适应能力。在细胞壁特性中，果胶含量及其甲基化程度显得尤为重要，这由根尖A1损伤与果胶含量及其甲基化程度之间的正相关性表明。硅诱导的铝毒性的改善可能与体内效应有关。经过铝处理的植物比未经铝处理的植物在根尖细胞壁中积累的硅含量更高，因此减少了细胞壁中易交换的铝的含量。 A8-鞘脂去饱和酶转化的玉米植株的实验表明，质膜特性对Al抗性的重要性，这种植物受Al的影响大于野生型，并且抗性和抗性之间的脂肪酸去饱和度差异也不同。玉米敏感品种。变化很小，但是用9-酰基去饱和酶转化的酵母进行的实验表明，去饱和度的很小变化会导致铝抗性非常强烈地增加。

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