ISWC OpenIR  > 水保所知识产出(1956---)
玉米根系吸水调控机制
刘 小 芳
Subtype博士
Thesis Advisor张 岁 岐
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword玉米 根系吸水 品种 根系形态 干旱胁迫 硝态氮 铵态氮
Abstract

根系吸水对于作物生长发育及产量有着重要的影响,深入了解根系吸水机
理,分析不同调控措施对根系吸水的影响,对于实现节水、高效、高产的现代农
业具有重要的科学价值和现实意义。本论文以玉米为研究对象,采用水培试验和
盆栽试验相结合的方法,就不同玉米品种、水分条件和氮素形态调控措施下,作
物生长、生理特性、根系吸水能力、水分利用效率等问题进行了研究,以期为作
物的高效用水机理提供科学依据。研究主要取得以下结果:
(1 ) 水分条件 明显影响了 玉米根系形态特征, 不同玉米品种 间存在显著差
异, 与天四和 478  相比,户四具有较大的根系 生长 。与正常供水相比,干旱胁迫
下三个玉米品种根系总表面积和总根长增加,根系干重降低。干旱胁迫显著增加
玉米初生根长、次生根长、种子根主根长、种子根总根长、一级侧根密度和平均
长度。两种水分条件下,三个玉米品种间的根系生长总体表现为户四优于 478
和天四的趋势。与其它两个品种相比,户四具有较高的根系干重、较大的总根长
和总表面积。而户四较大的总根长主要是由于初生根特别是种子根长较大,一级
侧根密度和长度也较大,而次生根长的品种间差异不显著。总体而言,户四的根
系生长体现出在适应水分环境方面的优势。
(2 ) 水分条件 明显影响了 玉米根系 吸水 能力 , 不同品种 在细胞、单根和整
根 水平的根系吸水 能力 存在 显著差异,表现为户四根系吸水能力优于天四和
478 。细胞水平下,水分胁迫显著降低了三个玉米品种的根皮层细胞膨压,表现
为户四>天四>478 且品种间差异显著,但正常供水条件下品种间差异不显著。用
HgCl 2 和 2-巯基乙醇先后处理根皮层细胞,其水导先降低后升高,但并未恢复到
初始水平,表明 HgCl 2 抑制了水通道蛋白活性,2-巯基乙醇则使水通道蛋白活性
部分恢复。两种水分条件下各处理阶段根皮层细胞水导均表现为户四>天四>478
且品种间差异显著,水分胁迫显著降低了根皮层细胞水导。单根水平下,两种水分条件下的玉米静水压下单根水导均为户四>天四>478,品种间差异显著,且水
分胁迫显著降低了其径向导度和轴向导度。不同品种在渗透压下也有相同趋势。
单根解剖结构与单根水导具有显著的相关性,单根径向导度与皮层厚度占根直径
的比例呈负相关关系(R = – 0.77, P < 0.01);单根轴向导度则主要受木质部导管
的影响,与中央木质部导管直径(R = 0.75, P < 0.01)和木质部导管总横截面积
(R = 0.93, P < 0.01)呈正相关关系。整根水平下,两种水分条件下三个品种的
整根水导呈户四>天四>478 的趋势,品种间差异显著,且水分胁迫显著降低了玉
米整根水导。
(3) 土壤 水分条件 和氮素形态显 著影响 了 玉米地上部和地下部生长。与正
常供水相比,干旱胁迫对玉米地上部和地下部生长均有抑制作用,增加植株根冠
比,促进光合作用产物在根部积累。施用氮肥能显著改善玉米生长,且随着施氮
量增加效果更显著。相同供氮水平下,硝态氮和铵态氮混施显著提高玉米地上部
和地下部生物量,显著降低根冠比,更有利于植株生长,特别是根系的生长发育。
水分条件和氮素形态主要通过对玉米净光合速率和叶绿素等因子的调控,从而影
响作物光合作用,调控作物生长。
(4) 土壤 水分条件 和氮素形态显著影响 了 玉米地上部蒸腾耗水和根系吸水
能力,从而调控植株体内水分 平衡。水分胁迫条件下玉米地上部蒸腾耗水和根系
吸水能力较正常供水显著降低。同一供水条件下,施氮能显著提高玉米的地上部
蒸腾速率和根系吸水能力,且高氮处理优于低氮处理。硝态氮和铵态氮混施较相
同施用量单施处理能更有效增强地上部蒸腾作用,提高生物量水分利用效率;而
单施硝态氮可增强细胞和整根水平的根系吸水能力,更有利于使植株保持较好的
水分状况。
关键词:玉米;根系吸水;品种;根系形态;干旱胁迫;硝态氮;铵态氮

Other Abstract

Water uptake by roots plays an important role in the growth and development as
well as the yield of crops. In-depth understanding of the mechanism water uptake by
roots and analysis the impact of different control measures on water uptake by root
are of scientific values and practical significance to water-saving, high-efficiency,
high-yielding modern agriculture. To investigate the mechanism of water uptake by
crop roots, this research project chose maize as the plant material and employed a
combination method of water culture experiment and pot experiment. The key crop
indices, e.g., crop morphogenesis, physiological characteristics, water uptake ability
by roots, and water use efficiency were determined under different control measures
in terms of corn genotype (i.e., Hu 4, Tian 4, and 478), water condition (i.e., well
watered and water deficit conditions), and nitrogen (N) form of the fertilizer
(nitrate-N and ammonium-N). The results should contribute to understanding of the
mechanism of efficient water use by crops. The main findings of this study were as
follows:
(1) Water supply conditions substantially influenced the morphological
characteristics of maize roots. There were significant variations among different
maize genotypes. Hu 4 produced a larger root system than Tian 4 and 478.
Compared with well watered, water deficit increased the total root surface area and
total root length while decreasing the root dry weight of different maize genotypes. In
addition, water deficit significantly increased the length of primary and secondary
roots, the length and main root length of seminal roots, and the linear frequency and
length of first-order lateral roots. Under different water regimes, the root growth of
Hu 4 was better than that of 478 and Tian 4. As compared to 478 and Tian 4, Hu 4 had greater root dry weight, total root length, and total surface area. In particular, Hu
4 was characterized by large length of primary roots as well as large linear frequency
and length of first-order lateral roots, whereas the length of secondary roots showed
no significant variations among different maize genotypes. Overall, the root growth of
Hu 4 showed advantages in adapting to the water conditions.
(2) Water supply conditions substantially influenced water uptake by maize
roots. There were significant variations among different maize genotypes at
cellular, single root and whole root system levels, with the water uptake ability of
Hu 4 was higher than that of Tian 4 and 478. At cellular level, the turgor of cortical
root cells of the three maize genotypes decreased under water deficit, and the turgor
ranking was in the order Hu 4 > Tian 4 > 478. But, the turgor of the three maize
genotypes was with no genotypic differences under the well watered condition. After
treated by HgCl 2  and 2-mercaptoethanol under two water levels,cell hydraulic
conductivity (Lp c ) of the three maize genotypes were firstly decreased,then increased,
and the final values were even lower than the original values. The results indicated
HgCl 2  inhibited the activity of aquaporins, and 2-mercaptoethanol parted reversed the
activity of aquaporins. The Lp c of the three genotypes substantially decreased in the
water deficit treatment, and the Lp c ranking was in the order Hu 4 > Tian 4 > 478 in
the two water treatments. At single root level, the hydrostatic hydraulic conductivity
(Lp sr ) of single roots varied among genotypes under the two water levels, with the
highest in Hu 4 and the lowest in 478. Radial hydraulic conductivity (radial Lp sr ) and
axial hydraulic conductance (L ax ) of the three genotypes varied similarly as Lp sr , and
water stress decreased radial Lp sr and L ax . The osmotic Lp sr in the Hu 4 was the
highest (Hu 4 > Tian 4 > 478) across the water conditions. The variations in hydraulic
parameters were related to root anatomy. Radial Lp sr was negatively correlated with
the ratio of cortex width to root diameter (R = – 0.77, P < 0.01), whereas L ax was
positively correlated with the diameter of the central xylem vessel (R = 0.75, P < 0.01)
and the cross-sectional area of xylem vessels (R = 0.93, P < 0.01). At whole root
system level, hydraulic conductivity (Lp wr ) of the whole root system followed the
same trend under the two water conditions, with the highest values in the Hu 4.
Moreover, the Lp wr of each genotype substantially decreased under water deficit.  (3) Soil moisture conditions and N forms significantly influenced the growth
of the shoot and root system of maize. Compared with well watered condition,
water deficit had an inhibitory effect on the growth of the shoot and root system of
maize, which increased the root-to-shoot ratio and promoted the accumulation of
products of photosynthesis in the roots. Application of N fertilizer significantly
improved plant growth in a dose-dependent manner. When applied at the same level,
the mixture of nitrate-N and ammonium-N significantly increased plant biomass of
the shoot and root system while significantly reducing the root-to-shoot ratio. Thus,
this application of mixed N fertilizers was more conducive to plant growth, especially
the root growth and development. Soil moisture conditions and N forms mainly
through regulation of the net photosynthetic rate and the chlorophyll content of maize
leaves, further influencing the photosynthesis process and regulating growth of the
crop.
(4) Soil moisture conditions and N forms significantly influenced the
transpiration and root water uptake capability of the above-ground part of
maize, thereby regulating water balance in plant body. Under water deficit, the
transpiration and root water uptake capability of the above-ground part of maize were
significantly lower than those under well watered condition. Under the same water
conditions, application of N fertilizers significantly improved transpiration rate of the
above-ground part and water uptake ability of maize roots, and the improvement
effect was stronger in higher-N treatments than in low-N treatments. Application of
nitrate-N mixed with ammonium-N was more effective than single use of the N
fertilizer in enhancing th e transpiration of the above-ground part of maize and
improving the water use efficiency of the biomass. On the other side, application of
nitrate-N alone enhanced the water uptake ability by roots at cellular and whole root
system levels, thus facilitating the plants to maintain good water conditions.
Key words: Maize; Water uptake ability of roots; Genotype; Root morphology; Water
deficit; Nitrate-N; Ammonium-N

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8967
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
刘 小 芳. 玉米根系吸水调控机制[D]. 北京. 中国科学院研究生院,2013.
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