【作者】 华瑞；

【导师】 李世清；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2008， 硕士

【摘要】 磷素不足已成为限制作物产量重要因素之一,因此,如何提高小麦、玉米对介质磷素吸收利用能力,筛选“磷高效”种质资源,对充分发挥植物高效利用土壤磷素营养潜力具有重要科学和实践意义。以往对小麦、玉米磷营养研究往往集中在单一作物不同基因型的比较,而有关小麦和玉米两种作物对磷素反应差异的比较性研究还较少。本试验选取2种不同分蘖类型的冬小麦基因型（多分蘖品种小偃22号和少分蘖品种兰考4号）和2个不同产量潜力的玉米基因型（高产品种屯玉65号和低产品种户单4号）作为研究对象,利用营养液培养方法,研究了在介质不同供磷水平（无磷、低磷胁迫、中等磷胁迫和标准供磷）下冬小麦和玉米不同基因型苗期冠层、根系及整株的生物量和磷积累量,作物光合荧光参数、根系形态特征和生物学性状等,系统比较了两种作物不同基因型间磷素吸收利用效率的差异,为快速筛选磷高效基因型和耐低磷基因型提供选择指标和一定理论依据。研究获得以下主要结果:1.从植株生物量指标看,小麦和玉米两种作物在苗期对磷胁迫均有良好反应,且玉米对磷素的反应并不比小麦逊色,只是二者对磷素敏感的阶段不同,且这种敏感性因作物基因型差异而异。植株不同部位对磷素反应亦不相同。在苗期早期生长阶段（即出苗后40 d以前）,作物冠层生长并不需要介质较高供磷水平,而在苗期后期（即出苗后40～50 d）,磷胁迫对冠层生长会产生明显抑制作用;介质较低供磷水平有利于促进玉米根系生长,而对小麦根系则需要较高供磷水平。总体而言,在苗期早期生长阶段,玉米对介质低磷胁迫的反应强于小麦,而进入苗期后期生长阶段,小麦的反应又强于玉米。2.介质供磷水平对小麦和玉米苗期磷累积量的影响显著不同,且因作物基因型、器官及测定时期不同而异。不同器官磷素养分累积量主要取决于生物量,而不是磷含量。介质供磷后,苗期早期生长阶段（出苗后25 d以前）,小麦磷累积量对介质最佳供磷水平的反应较玉米高;在苗期后期（即出苗后40～50 d）时,小麦和玉米最佳供磷水平一致。如果以低磷胁迫（P1）作为对比进行分析,玉米苗期整株（冠层+根系）磷累积量对介质供磷的敏感性比小麦更强。试验供试小麦基因型间差异较玉米基因型间差异大,即兰考4号对介质供磷的敏感性较小偃22号强,屯玉65号和户单4号对介质供磷反应的敏感性基本一致。3.在缺磷胁迫下小麦和玉米叶片的Pn、Gs、Ls均降低,而胞间CO₂（Ci）浓度升高,说明试验作物叶片Pn的降低主要受非气孔因素限制。在介质完全缺磷情况下,小麦叶片Pn较玉米高;但供磷后,玉米叶片Pn显著大于小麦,且其对磷素的反应较小麦敏感。玉米不同基因型Pn在供磷水平间所表现出的规律性较小麦强,屯玉65号始终大于户单4号;而两种小麦基因型Pn的差异因供磷水平不同而异。缺磷处理下小麦、玉米叶片F_m、F_v、PSⅡ原初光能转换效率（F_v/ F_m）、PSⅡ潜在活性（F_v/ F₀）下降,F₀升高,表明PSⅡ的光能转换和利用效率降低。玉米低磷处理P1叶片F_v/ F_m降低,而小麦叶片F_v/F_m并未降低,表明低磷胁迫对小麦未产生光抑制;因此,以P0处理参比,玉米荧光参数对介质供磷的反应比小麦更敏感。两种玉米基因型F_v/ F_m、F_v/ F₀差异的规律性较小麦明显。户单4号受磷胁迫的影响小于屯玉65号,表现出较强的耐低磷能力。4.处理50 d后根系测定结果表明,磷素供应显著增加小麦和玉米根系干重、根长、根表面积和根体积,这进一步证明了磷可促进根系的生长,增大根系在土壤中的养分吸收空间。试验供磷处理对小麦和玉米根长的增加作用主要是细根长度的增加。从供试不同基因型看,小偃22号与兰考4号相比、屯玉65号和户单4号相比,在低磷胁迫情况下前者较后者有较大的根部生物量和根冠比,根系的生长状况相对较好。5.供磷水平显著影响小麦和玉米株高、叶面积等生物学性状。缺磷处理下小麦不分蘖或分蘖数减少。从不同基因型看,对小麦来说,供磷后兰考4号分蘖数、株高及叶面积均高于小偃22号;对玉米来说,供磷后户单4号叶片数、株高及叶面积等性状均高于屯玉65号。与玉米不同,磷素供应对苗期冬小麦的影响主要通过影响分蘖而影响生物量。更多还原

【Abstract】 Phosphorus stress is one of the key factors to limit crop production. Screening of crops varieties which efficiently use phosphate is important to increase the crops capacity to utilize soil phosphate. Few researchers reported the differences of response to phosphate between wheat and maize.Two varieties of wheat （Xiaoyan 22 with more tillerings, and Lankao 4 with less tillerings） and maize （Tunyu 65 with potentially higher yield, and Hudan 4 with potentially lower yield） were grown in Hoagland solution to investigate the effects of phosphate concentration on biomass of shoot and root, P uptake, Chlorophyll fluorescence parameters and root morphological character of them at different seedling stage. Phosphate levels referred to 0 （P0）, 0.05 （P1）, 0.3 （P2）, 0.5 （P3） P2O5 mmol·L^-1. The main results of the research are as follows:1. Both of wheat and maize responded to low phosphorus stress. However, the responses were different in growth period and genotypes. Shoot biomass and root biomass of crops also responded differently. During the early stage of seedling （40 days after emergence）, shoot biomass of crops didn’t decrease significantly with the low concentration of phosphate comparing with normal phosphate (0.5 P₂O₅ mmol·L^-1) while opposite results were found during the later stage of seedling （40～50 days after emergence）. Under low-phosphate stress, root biomass of maize increased while root biomass of wheat was found to be decreased. Total biomass of maize was more sensitive to the reduction of phosphate concentration than that of wheat during the early stage of seedling while the reverse was true during the later stage of seedling.2. There were different effects of phosphate level on P uptake by wheat and maize. They also depended on genotypes, organs and time of measuring. P uptake in different parts of crop mainly depended on biomass rather than P concentration of crop. The maximum P uptake by wheat was higher than maize during the early seedling stage （25 days after seedling emergence）, while no difference was found during the later seedling stage （40-50 days after seedling emergence）. When 0.05 mmol·L^-1 treatment was used as a control, P uptake of whole plant for maize was more sensitive to P in medium than for wheat, Lankao 4 was more sensitive than Xiaoyan 22, and no difference was found between Tunyu 65 and Hudan 4. 3. Leaf net photosynthetic rate （Pn）, stomatal conductance （Gs） and stomatal limiting value （Ls） of wheat and maize were gradually reduced while intercellular CO₂ concentration （Ci） was enhanced because of P deficiency, suggesting that the decreased photosynthetic rate might be controlled by non-stomatal limitation. When no phosphate was applied, leaf net photosynthetic rate （Pn） of wheat was higher than maize while Pn of maize was significantly higher than wheat and it was also more sensitive to phosphate when phosphate was supplied. Leaf net photosynthetic rate （Pn） of Tunyu 65 was always greater than Hudan 4 while the difference of Pn between two wheat genotypes was fluctuant with the phosphate levels. Comparing with normal phosphate level （P3）, lack of phosphate （P0） caused reduces of maximum fluorescence （F_m）, variable fluorescence （F_v）, the intrinsic photochemical efficiency （F_v/ F_m） and potential activities （F_v/ F₀） of wheat and maize leaves and increases of original fluorescence （F0）, indicating that the photo change and PSⅡuse efficiency decreased. F_v / F_m of maize leaf was reduced due to P deficiency （P1） while that of wheat leaf wasn’t. This suggested that photo-inhibition of photosynthesis happened to maize under low phosphorus stress. Hudan 4 showed greater tolerance to low phosphorous stress than Tunyu 65.4. Root dry weight, length, surface area and volume of wheat and maize increased significantly when phosphate was applied, comparing with P0. Increase of root length attributed mainly to fine roots. Xiaoyan 22 had greater root biomass and root shoot ratio under low-P stress than Lankao 4 while Tunyu 65 had greater root biomass and root shoot ratio than Hudan 4.5. When phosphate was applied, Lankao 4 had greater tillers number, height and leaf area than Xiaoyan 22 while Hudan 4 had greater leaves number, height and leaf area than Tunyu 65.更多还原