【作者】 张丽梅；

【导师】 贺立源； 李建生；

【作者基本信息】 华中农业大学 ， 植物营养学， 2005， 博士

【摘要】 玉米是世界第三大粮食作物，也是我国主要的粮食作物、饲料作物及工业原料。缺磷是限制玉米生产的重要因素之一，改良玉米的磷营养效率可经济有效地解决这一问题。本研究对来自国内外不同遗传背景的300个玉米自交系进行苗期土培筛选，并对部分材料进行全生育期鉴定，获得一部分耐低磷和低磷敏感的自交系。同时利用选出的典型材料深入开展耐低磷营养及生理特性的研究，以期为磷效率改良工作提供材料和理论上的依据。主要研究结果如下： 1．采用苗期初筛并结合全生育期鉴定的方法，通过大规模土培试验，筛选出一批典型耐低磷和低磷敏感的玉米自交系。该方法省时省工且符合生产实际，筛选的自交系典型可靠。 2．首次通过多个磷浓度梯度试验，提出玉米耐低磷苗期筛选的合适的P处理浓度和行之有效的筛选指标。确定在严重缺磷土壤(有效磷含量小于5mg／Kg)中进行苗期筛选时，以0.10g／Kg的磷用量作为低磷处理浓度，以0.25g／Kg或0.30g／Kg的磷用量作为正常磷处理浓度较为合适，鉴定效果较好。首次提出并证明苗期筛选以综合指数，即缺素症状和干重相对指数的加权平均值(权重均为1／2)作为筛选指标更可靠更全面。通过大田产量试验验证，本筛选方法的可靠性可达76.9％。 3．对不同基因型玉米阶段生长发育特征进行了研究，发现不同自交系在生长发育过程中对低磷胁迫的反应存在明显差异。苗期和拔节期，低磷胁迫下，耐低磷自交系表现为相对植株干重较高，无缺磷症状或症状轻微；孕穗期，耐低磷自交系上部叶干重、茎干重受低磷影响的程度显著低于敏感自交系；吐丝期，耐低磷自交系的穗位高、雄花分枝数、功能叶面积均显著高于敏感自交系；成熟期，缺磷时耐低磷自交系的相对产量较高。缺磷还影响玉米的生育进程。低磷胁迫下，敏感自交系99152S的抽雄期、抽穗期、吐丝期和散粉期显著延迟，而耐低磷自交系99180T和99239T受影响较小或几乎不受影响。 4．首次对不同基因型玉米各生育期对P的吸收、利用和分配特性进行研究，发现苗期和拔节期，磷吸收效率是决定耐低磷特性的主要变异来源，低磷胁迫下，耐低磷自交系99180T和99239T的相对植株吸磷量显著高于敏感自交系99152S；孕穗期，玉米耐低磷特性主要体现在上部叶磷累积量较高；吐丝期，低磷胁迫下耐低磷自交系99180T和99239T的磷吸收效率和再分配效率仍明显高于敏感自交系99152S，其中99239T主要表现为吸收效率较高，99180T则表现出更强的再分配能力。 5．营养学特性研究表明，玉米苗期P营养对其它元素的吸收利用有一定影响。缺磷抑制玉米植株对N的吸收，但耐低磷自交系受影响程度较敏感自交系小。低磷条件下，耐低磷自交系不仅比低磷敏感自交系吸收和累积钾元素的能力强，且适当低磷处理有利于某些耐低磷自交系对K的吸收，严重缺磷抑制所有自交系对K的吸收。缺磷使Ca、Mg百分含量增加，累积量减少，但吸磷能力较强的耐低磷自交系更多还原

【Abstract】 Maize is the third largest food crop in the world, and also the major crop for food, fodder and industrial material in China. The deficiency of P is one of the main problems that hinder the productivity of. maize. Fortunately, it could be solved through the improvement of P efficiency effectively and economically. In this study, 300 maize inbred lines of various genetic backgrounds from both domestic and abroad were screened at seedling stage with soil culture, and some inbreds were tested in full-life stage with block experiment in the field. Thus, some inbreds of low-P resistance and low-P sensitive were obtained. Meanwhile, sortie typical lines were selected to study their nutritional characters and physiological mechanism for low-P tolerance. Based on the studies, we expected to lay some theoretical foundations for the improvements of P efficiency and provide materials for such studies. The main results of this study were summarized as follows:1. Though seedling screening and full-life identifying with soil culture to gain some typical low-P tolerant and low-P sensitive maize genotypes. The methods were not only practical but also time and labor economic. The results yielded were reliable.2. P concentration for seedling screening and related indicators were proposed by multi P concentration gradient tests. The study revealed that the concentration of 0.10g/Kg is suitable for low-P treatment and 0.25 or 0.30g/Kg is proper for normal P treatment in the seedling screening in serious P deficiency soil. The synthesized index for seedling screenings was firstly presented and verified to be reliable and comprehensive. It was defined as the mean of relative P-deficiency symptom and relative dry weight. The field test showed that the reliability of this method could reach 76.9%.3. Characteristics of growth and development of certain stages were studied for different maize genotypes. It was illustrated that under low-P stress, P-tolerant lines had higher dry weight, showed no or slight P-deficiency symptom compared with that of P-sensitive lines at seedling and steming stages. The dry weights of upper leaves and stems were significantly less affected than P-sensitive lines at earing stage. At silking stage, some other indicators such as ear height, number of staminate flower branches and areas of functional leaves were observed to be significantly different among of different lines besides plant dry weight. The relative values for such indicators of P tolerant lines were much higher than that of P sensitive lines. In mature stage, yields of P-tolerant lines were higher as well. The results of this paper also showed that the P deficiency could also influence the growth stages by delaying tasselling, heading, pollen-shedding and silking stage for P sensitive line 99152S, while P tolerant lines such as 99180T and 99239T were less or non affected.4. Characteristics of P uptake, utility and distribution are found to be different for different lines in all stages. At seedling and steming stages, the efficiency of P uptake is the main contributor to low-P tolerance. And the P uptake amounts of P-tolerance lines 99180T and 99239T are significantly higher than P sensitive line 99152S under low P stress. At earing stage, the characteristics of low P tolerance are represented by the higher P accumulated amount in upper leaves. When come to the silk stage, P uptake and redistribution efficiencies of 99180T and 99239T are still significantly更多还原