【作者】 张木；

【导师】 胡承孝；

【作者基本信息】 华中农业大学 ， 植物营养学， 2013， 博士

【摘要】 钼和硒是人体所必需的营养元素,人体钼硒缺乏均会导致生理代谢上的疾病,摄入适量的铝和硒还可以提高人体的抗氧化机能。钼和硒在土壤中有很多相似的化学特性,二者对植物的有效性均随着土壤pH值的下降而降低,缺钼土壤也多伴随着缺硒。中国有大面积的土壤存在着钼硒缺乏的状况,人体从粮食作物中所摄取的钼硒含量就有所不足,因此铝硒配施不但具有实践意义而且还具有人体营养学意义。以往的研究大多关注于钼与硫、钼与磷、硒与硫、硒与磷关系的研究,而对于铝与硒关系的研究尚没有系统性的报道。钼与硒均以阴离子酸根的形态被植物吸收利用,并且都可以通过磷酸盐及硫酸盐转运子进入植物体内,因此研究钼与硒的关系还具有很强的理论研究意义。本文在总结以往既有零星研究的基础上,通过土培试验和水培试验,系统的研究了小白菜钼硒营养机制。得出主要结论如下：1.通过土培试验研究了铝硒配施对小白菜产量及品质的影响。结果表明：铝硒配施在一定程度上增加了小白菜的产量,提高了小白菜Vc、可溶性糖、可溶性蛋白、粗蛋白、有机酸及氨基酸的含量,在一定程度上降低了小白菜硝酸盐的含量,进而改善了小白菜的品质；在提升小白菜品质方面,施钼的效果要明显好于施硒的效果。2.通过水培试验研究了小白菜对钼、硒养分吸收的影响。结果表明：硒不但能抑制小白菜对钼的吸收,而且还能抑制过多的钼向地上部转移,避免过量的钼对植物体产生毒害作用。当外界硒浓度达到一定水平根硒相对饱和时,小白菜根中硒含量并没有随着施硒的量增加而增加,此时施钼对小白菜硒的吸收没有显著地影响,小白菜对硒的吸收能力仅取决于向地上部的转移能力；当小白菜根硒含量没有达到相对饱和的状态时,施钼对小白菜硒的吸收有着明显的抑制效应。尽管在此水培试验中钼与硒之间表现出了拮抗效应,但是钼与硒仍能容易的从外界转移至植物体,从根中转移至地上部,因此在生产中钼硒配施可以满足生产富铝富硒作物的需求。3.通过短期施用钼、硒试验研究小白菜对钼、硒吸收动态的影响。结果表明：在动态吸收试验中,长期缺钼、缺硒生长条件下的小白菜当重新供给铝硒时,施钼对小白菜硒的吸收表现出了抑制效应,尽管所供应的硒浓度在长期培养试验中是使根硒达到饱和状态的浓度,施铝仍然对小白菜硒的吸收也表现出了拮抗作用,但是随着处理时间的延长,施钼对硒吸收的拮抗作用会越来越小,在根硒达到相对平衡状态以后,铝对硒吸收的影响就会减弱。各亚细胞结构的表现特性基本类似,大致呈拮抗效应。在吸收动力学参数方面,施硒对小白菜钼吸收动力学特征参数有负面影响,而施铝对硒吸收动力学参数的影响则有着复杂的两面性,一方面缘于施钼对植物根系的改良作用,Km值和Cmin向着有利于硒吸收的方向发展,另一方面缘于竞争,Vmax又表现出略有降低的趋势。4.通过水培试验研究小白菜铝硒配施对小白菜体内铝、硒化学形态的影响。结果表明：施硒能增加小白菜地上部及地下部醇溶态钼、水溶态钼含量,对小白菜地上部及地下部盐溶态及醋酸溶态钼的含量则表现出了拮抗效应,对地上部盐酸溶态钼含量影响不大,但对地下部盐酸溶态钼含量则有着促进作用。施钼对小白菜地上部醇溶态、水溶态硒的含量影响不大,提高了盐溶态及盐酸溶态硒的含量,降低了醋酸溶态硒的含量；施铝对小白菜地下部醇溶态硒含量影响不大,降低了水溶态硒的含量,增加了盐溶态、醋酸溶态及盐酸溶态硒的含量。施用四价硒源对小白菜可食部位硒的有机化较为有利,施钼能促进高硒水平小白菜体内硒的有机化。5.通过土培连作试验研究施用钼硒对铝、硒在土壤中后效的影响。结果表明：钼硒配施能增加第1茬小白菜的产量,对第2茬小白菜产量影响不大；铝硒配施可以促进第1茬及第2茬小白菜对钼和硒的吸收,钼在土壤中有一定的后效作用,可以满足两茬作物的需求,施硒仅能满足第1茬作物富硒的需求；铝可以满足两茬小白菜富钼的需求是因为钼在两茬种前都具有较高的有效性,施硒仅可以满足第1茬富硒的需求是因为硒在第1茬种植后有大量水溶态和交换态的硒向低有效性的方向转化。6.通过水培试验及土培试验研究铝硒配施对小白菜钼、硒吸收的影响。结果表明：钼硒配施对小白菜钼、硒吸收的影响存在着复杂的两面性,在水培试验中铝与硒之间有着拮抗效应,而在土培试验中二者又有着协同效应。铝为植物所必须的营养元素,在缺钼土壤上施用适量的钼对生长的促进作用所带动的植物对硒的吸收效应可能会大于钼对硒的拮抗效应,此时就表现出钼对硒吸收的促进作用。土壤不缺钼时,施铝对植物生长的促进作用就不是太明显,那么此时钼对硒的拮抗作用就会占主导地位。硒的有益和毒害的界限很窄,当硒对植物产生毒害又或是潜在毒害时,硒会对铝的吸收表现出拮抗作用。试验中土壤钼、硒均较为缺乏,施用低浓度的钼与硒,因此二者表现出了协同效应。水培试验中,钼、硒的有效性均较高,在最低的钼硒浓度时,植物体内钼、硒的含量是土培试验的数十倍,这说明水中的钼硒较易被吸收。此时钼与硒竞争转运子的效应就占了主导地位。7.研究了钼硒配施对盐胁迫下小白菜生长的影响。结果表明：施钼、施硒以及钼硒配施均提高了盐胁迫下小白菜的产量,其中以单施钼、钼硒配合施用的效果最佳,均达到了显著性水平；施钼和钼硒配施均增加了盐胁迫下小白菜体内钼的含量,特别是提高了缺钼土壤小白菜的钼营养水平；施钼、施硒以及钼硒配施提高了小白菜抗氧化酶活性,增加了非酶类抗氧化物质的含量,进而增强了小白菜的抗氧化防御能力；施钼、施硒以及钼硒配施增加了小白菜的渗透调节物质含量,改善了小白菜的渗透调节能力；施钼以及钼硒配施对光合速率均有不同程度的提高,单独施钼主要是通过非气孔因素来提高的,而钼硒配施则是通过气孔因素来提高的。在增强小白菜抗盐胁迫的效果上,以单施钼以及钼硒配施的效果较好,单独施硒的效果稍差,但是对缓解盐胁迫也具有一定的作用。更多还原

【Abstract】 Molybdenum and selenium are both essential trace elements for human health. A low intake of Mo and Se may increase the risk of many diseases, and intake of a certain amount of Mo and Se can also improve the body’s antioxidant capacity. There are many similar chemical properties of Mo and Se in the soil. In low soil pH, bioavailability of Mo and Se both trend to decrease. Large areas of soil are Mo deficiency, and most of those areas go with Se deficiency. In China, a large area of the land is Se and Mo deficiency and often results in the lack of Se and Mo in human body in this area. Therefore, co-application of Mo and Se not only has significance of human nutrition but also has significance of practical. Previous studies has focused more on Se-S, Mo-S, Se-P and Mo-P interactions in soil and solution culture, but little has been paid to the possible interactions of Mo-Se. Mo and Se are both absorbed by plants in form of anion, and they were both transported via sulphate and phosphate transporters. Therefore, the study of the relationship between Mo and Se also has a strong theoretical significance. On the basis of previous studies, soil and hydroponics trials were conducted to investigate the interactive effects of Mo and Se and its mechanism of Chinese cabbage. The Main results as follows:1. A pot experiment was conducted to determine the effects of co-application of Mo and Se on yield and quality of Chinese cabbage. The results showed that co-application of Mo and Se could increase yield, contents of vitamin C, soluble sugar, soluble protein, crude protein, organic acids and amino acids, as well as decrease nitrate content of Chinese cabbage. The effect of application of Mo is better than the effect of application of Se in improving quality of Chinese cabbage.2. A solution culture experiment was conducted to determine the effects of co-application of Mo and Se on nutrition uptake of Chinese cabbage. The results showed that Se decreased Mo concentration and inhibited translocation of excess Mo from roots to shoots in Chinese cabbage. When Se concentration reaches a certain level in the outside, root Se content did not increase with an increasing solution Se concentration, and application of Mo had no significant effect on plant uptake of Se and the capacity of Chinese cabbage uptake of Se depended only on the ability of translocation of Se from root to shoot. When root Se concentration was not saturated, application of Mo significantly decreased Se concentration. Although, there had a strong antagonism between Mo and Se on nutrition uptake, results showed that both Mo and Se could be easily translocated from solution to plants and from roots to edible parts. Therefore, co-application of Mo and Se could meet the need of producing Mo-enriched and Se-enriched crops.3. A short-term solution culture experiment was conducted to determine the effects of co-application of Mo and Se on Mo and Se absorption dynamics of Chinese cabbage. The results showed that there had a strong antagonism between Mo and Se on nutrition uptake, especially when Mo and Se deficiency persisted for long periods. Although the solution Se level can make root Se reach saturate, application of Mo decreased Se concentration. However, with the treatment time increasing, the antagonism between Mo and Se will become smaller and smaller. When the root Se concentration was saturated, application of Mo had no effect on Se uptake in Chinese cabbage. The performance characteristics of subcellular structures were similar, there has an antagonism between Mo and Se in subcellular structures. The effect of application of Se on the absorption kinetics parameters of Mo had a trend that it was not conducive to the absorption of Mo. The effects of application of Mo on the absorption kinetics parameters of Se had complex two sides. Due to the positive role of Mo on Chinese cabbage, both Km and Cmin had a trend that it was conducive to the absorption of Se. But due to competition between Mo and Se, Vmax had a slightly decreasing trend.4. A solution culture experiment was conducted to determine the effects of co-application of Mo and Se on chemical forms of them. The results showed that application of Se increased alcohol soluble and water soluble Mo concentrations of roots and shoots and decreased salt soluble and acetic acid Mo concentrations of roots and shoots in Chinese cabbage. Application of Se had no significant effect on shoot hydrochloric acid Mo concentration, but application of Se increased root hydrochloric acid Mo concentration. Application of Mo had no significant effects on shoot alcohol soluble and water soluble Se concentrations, application of Mo increased salt soluble and hydrochloric acid Se concentrations and decreased acetate acid Se concentration. Application of Mo had no significant effect on root alcohol soluble Se concentration, and application of Mo decreased water soluble Se concentration and increased salt soluble, acetate acid and hydrochloric acid Se concentrations. Application of tetravalent Se was conducive to the conversion of inorganic Se to organic Se, and application of Mo can promote the transformation of inorganic Se to organic Se in high Se level.5. A pot experiment was conducted to determine the effects of application of Mo and Se on soil available Mo and Se contents during two successive planting periods. The results revealed that yield was significantly increased by application of Mo and Se in the first harvest, which was not significantly increased by application of Mo and Se in the second harvest. Both application of Mo and Se could prompt Chinese cabbage uptake of Mo during the two successive planting periods; Soil available Mo maintained high level during the two successive planting periods, and application of Mo could meet the needs of producing Mo-riched cabbage during the two successive planting periods; Though both application of Mo and Se could prompt Chinese cabbage uptake of Se during the two successive planting periods, water souble Se and exchangeable Se were decreased after the first harvest and application of Se could only meet the need of producing Se-riched cabbage in the first harvest.6. Soil and solution culture experiments were conducted to determine the effects of application of Mo and Se on Mo and Se nutrition uptake in Chinese cabbage. The results showed that there had a strong antagonism between Mo and Se in solution culture experiment and had synergies between Mo and Se in soil experiment. Mo is an essential micronutrient for plants, and appropriate application of Mo can promote plant growth and then stimulate the absorption of selenium in Mo deficiency soil. Application of Mo had no obvious effect in promoting plant growth in Mo rich soil, and the antagonism between Mo and Se will be dominate. The beneficial and harmful boundaries of Se for plants are very narrow. When plants suffer from Se toxicity or potentially toxicity, Se would decrease Mo uptake. In our experiment, application of Mo and Se in Mo and Se deficiency soil, there had synergies between Mo and Se. In solution culture experiment, both Mo and Se had a very high effectiveness. The contents of Mo and Se of Chinese in the lowest solution Mo and Se levels are few times than the contents of Mo and Se of Chinese cabbage in soil experiment, and the transporters competition between Mo and Se will be dominate.7. A pot experiment was conducted to determine the effects of Mo and Se on the growth of Chinese cabbage under salt stress. The results showed that application of Mo and Se increased yield of Chinese cabbage, and the best treatments were combination of Mo and Se. The contents of Mo in Chinese cabbage were increased by application of Mo and combination of Mo and Se, especially when soil Mo deficiency. Mo and combination of Mo and Se increased activities of antioxidant enzymes and the contents of non-enzymatic antioxidants and then increased the capacity to eliminate active oxygen. Application of Mo, Se and combination of them increased osmotic-adjustment products contents and then increased the ability of osmotic-adjustment. Application of Mo and combination of Mo and Se increased photosynthesis rate in varying degrees. Application of Mo increased photosynthesis rate by non-stomatal factors, and combination of Mo and Se increased photosynthesis rate by stomatal factors. Mo and combination of Mo and Se were the best treatments in resisting salt stress of Chinese cabbage. Application of Se played a very small role in enhancing salt stress tolerance in Chinese cabbage.更多还原