ISWC OpenIR  > 水保所知识产出(1956---)
密度和根修剪对冬小麦产量及水分利用效率的影响
方燕
Subtype博士
2010-11
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword冬小麦 产量 水分利用效率 黄土旱塬 竞争能力 根系效率
Abstract

小麦作为世界上主要的粮食作物,产量的增加主要来自于新品种的培育和不断改
进的田间管理。在水资源不足的干旱半干旱地区,提高籽粒产量和水分利用效率是两
个同等重要的目标。本文采取盆栽与大田试验相结合的技术路线,以黄土旱塬区冬小
麦品种长武135 为实验材料,探讨冬小麦播种密度和人工干扰根系大小对同化产物生
成、分配、籽粒产量形成以及对土壤水分消耗的影响,从而为提高产量和水分利用效
率寻找新的科学途径。
本研究共设置两个实验:
实验1:
(1) 2006/07 设置盆栽试验和大田试验。盆栽试验设置四个处理:(1)常规密度不剪根
(LN: 12 株/盆,直径28cm× 高50 cm);(2) 常规密度剪根(LP); (3)高密度不剪根(HN:
15 株/盆,密度提高约25%);(4)高密度剪根( HP);设置两个水分处理,湿润水分处
理(WW):土壤水分含量为田间持水量的80-85%;干旱胁迫处理(MD):土壤
水分含量为田间持水量的55-60% ;根修剪(距主茎两侧3cm 处,垂直下切13cm)
于返青期进行(3 月2 日),垂直剪根量40~42%。
(2) 田间试验设置四个处理:(1) 常规密度不剪根(LN: 225 株m-2);(2) 常规密度剪根
(LP); (3)高密度不剪根(HN: 280 株m-2);(4)高密度剪根( HP),密度提高约25%。根
修剪(距主茎两侧3cm 处,垂直下切13cm)于返青期进行(3 月15 日),垂直剪根量
40~42%。
实验2:2007/08―2008/09 设置大田试验。实验设置三个密度:SR1 (225 株m-2:当
地常规密度);SR2 (280 株m-2);SR3 (340 株m-2),平均密度增长约25%;两个根修
剪处理:W (越冬期根修剪:11 月15 日);S (返青期根修剪3 月15 日); 不剪根处理
作为对照(CK)。两个时期根修剪处理的切根量均为40~42%。
主要研究结果如下:
1. 密度和根修剪对产量的影响。盆栽试验中,水分亏缺引起产量降低。湿润条件下,
密度增加产量显著增加。常规密度条件下,根修剪处理对产量没有显著影响,但高密度条件下产量增加显著。田间试验表明,在干旱年份,提高密度降低产量;
在水分条件较好的年份,提高密度进行根修剪处理后可以显著增加产量,这与盆
栽结果一致。
2. 密度和根修剪对水分利用的影响。盆栽试验表明,两个水分条件下,密度增加提
高耗水量;根修剪处理显著提高水分利用效率;在实验2 中,冬期剪根处理显著
减少了冬后-返青前的土壤耗水量,返青期根修剪则显著减少了返青期-成熟期的
土壤水分消耗,其土壤耗水量显著低于其它两个处理,因此返青期根修剪的水分
利用率为最高。
3. 密度和根修剪处理对冬小麦根系生物量的影响。实验1 证明,提高密度显著增加
根系生物量和根冠比;根修剪处理对小麦根系和根冠比的影响效果与此相反。田
间试验表明,提高密度显著提高花期时各个土层根系生物量,但根修剪显著减少
表层40cm 以上根系生物量,并且其80-120m 土层的根量和根系分配比例显著
增加。
4. 密度和根修剪处理对冬小麦群体结构的影响。实验2 表明,密度越高,叶面积指
数越高。但在降水量较少的2008 年,密度对叶面积指数(LAI)没有影响,单位面
积总分蘖数(有效分蘖和无效分蘖)随密度的增加而线性增长,有效分蘖数(成
穗数)不受密度影响,而单株分蘖则随密度的提高而降低。两个时期根修剪处理
均增加了叶面积指数,降低了总分蘖数和单株分蘖,但对有效分蘖没有影响。
5. 密度和根修剪对气体交换的影响。盆栽试验发现,密度增加和干旱胁迫处理显著
降低冬小麦光合速率和光合活性,但根修剪显著提高旗叶光合能力。实验2 表明,
随密度增加,旗叶光合速率(Pn)和光合活性下降,根呼吸速率提高(Rr),根系效
率(Pn:Rr)显著降低。与此相反,两个时期根修剪处理均显著提高旗叶光合速率并
降低了根呼吸速率,因此有较高的根系效率。由此可见,根系的减少提高旗叶的
光合能力,同时降低了根系耗碳量,将更多的光合产物用于产量建成。
6. 采用简化的de Wit 替代系列法阐明了冬小麦密度和根修剪对冬小麦竞争能力的
关系。在实验1 中,混播条件下不剪根小麦的相对产量均大于1,而根修剪小麦
相对产量均小于1。常规密度在湿润条件下,相对总产量为1.06,显著高于1.00,
说明与根修剪小麦相比,不剪根植株具有较强的竞争性。另外在水分条件较好时,
不剪根和根修剪处理在常规密度条件下混播可以显著增加产量。
7. 在大田条件下阐明了密度和根修剪对N、P 利用的影响。随密度的增加,叶片中
的N 含量和P 含量均呈显著下降趋势。两个时期的根修剪处理增加叶片氮磷元素的含量。由此可见,根修剪冬小麦拥有较高的光合速率也与其叶片中较高的N、
P 含量有关。
8. 实验2 指出,孕穗后地上部干物质积累和转移随密度增加而显著增加。两个时期
根修剪处理孕穗后干物质的积累显著高于不剪根处理。孕穗后干物质积累对籽粒
建成具有重要意义,因此根修剪植株产量的提高可能与其较高的孕穗后干物质积
累相关。
本研究表明,在黄土旱塬区达到多年平均降水量的情况下,提高密度和根修剪处
理可以增加籽粒产量和提高水分利用效率。提高密度后,产量的增加来源于单位面积
穗数和谷粒数的增加;而根修剪处理减少了冬小麦生育前期的耗水量,将更多的水分
用于花后灌浆,提高了水分利用效率,同时根修剪处理减少了无效分蘖,优化冠层结
构,并提高了光合速率和根系效率,减少了无益的根系碳损耗,增加了孕穗后干物质
积累,最终提高产量。但在严重干旱年份,提高密度后增加了对冬小麦个体间土壤水
分的竞争,最终引起产量降低。因此在该类地区通过提高密度和根修剪处理达到产量
和水分利用效率同步提高是有希望的。
关键词:冬小麦;产量;水分利用效率;黄土旱塬;竞争能力;根系效率

Other Abstract

As a major world crop, winter wheat has shown increased yields following advances
in breeding and crop management. On the semi-arid Loess Plateau of China, water stress is
one of the major limiting factors of yield for winter wheat. The improvements in grain
yield and water use efficiency (WUE) are two equally important goals in arid or semi-arid
areas. ChangWu 135, which developed for the semi-arid dryland agriculture area of the
Loess Plateau, was studied in the experiments. Pot experiments and field experiments were
conducted to assess whether seeding density in winter wheat affects grain yield and water
use efficiency when combined with root pruning by changes in the accumulation,
remobilization of photosynthate and water consumption.
Two experiments were conducted in our research:
Experiment 1:
(1) Pot experiment and field experiment were conducted in 2007/08. Pot experiment
comprised four treatments: (1) LN, low density (12 seedlings to a pot, 8 cm in diameter ×
50 cm high) and no root pruning; (2) LP, low density with root pruning; (3) HN, high
density (15 seedlings to a pot, 25% higher than low density) and no root pruning; and (4)
HP, high density with root pruning. Two water regimes were employed from stem
elongation: (i) plants maintained at 85% field capacity, and (ii) plants maintained at 55%
field capacity by regular watering. At stem elongation roots were pruned 40~42% on 2
March. And roots were cut back to keep their length to 13 cm and to limit their lateral
spread to 3 cm from the plant.
(2) Field experiment comprised four treatments: (1) LN: plants at low density (225 seeds
m-2, the recommended density in the region), roots not pruned; (2) LP: plants at low
density, roots pruned; (3) HN: plants at high density (280 seeds m-2, 25% higher than low
density), roots not pruned; and (4) HP: plants at high density, roots pruned. At stem
elongation roots were pruned by 40~42% on 15 March. And roots were cut back to keep their length to 13 cm and to limit their lateral spread to 3 cm from the plant.
Experiment 2: Field experiments conducted in 2007/08 and 2008/09 comprised. The
seeding rates were: SR1 (225 seeds m-2 the optimal seeding rate for the region),; SR2, 280
seeds m-2; and SR3, 340 seeds m-2. Two root pruning treatments were: W (roots pruned on
15 November just at the beginning of over-wintering period) and S (root pruned on 15
March at the beginning of the spring-growth stage); un-pruned plants (CK) served as the
control. Roots were pruned by 40~42%.
The main results are as follows:
1. The effects of grain yield by seeding rate and root pruning. In the pot study, the yield
reduction with water shortage. Grain yield increased significant with seeding rate
increased under the well watered condition. Normal seeding rate had no effect on grain
yield, while higher seeding rate increased grain yield significantly when root pruning.
Field Experiment observed that grain yield decreased with the seeding rate increased in
severe drought years. However, the reverse result was observed favorable weather.
Similar results found in pot experiment.
2. The effects of water use efficiency by seeding rate and root pruning. In pot experiment,
availability of water significantly increased overall water use as did increasing the
planting density (P<0.01), but root pruning increased water use efficiency significantly.
In experiment 2, root pruning in winter (W) primarily led to a significant decrease in
water use from winter to stem elongation stage. While root pruning in spring
significant reduced water use after stem elongation stage, used less soil water than
winter pruned roots and the un-pruned controls, and had highest water use efficiency.
3. The effect of root biomass by seeding rate and root pruning. In experiment 1 , root
biomass and R:S ratio significant increased with increasing seeding rate. The reserves
results found in root pruning treatment. In field experiment, root biomass in each layer
of soil were higher at the higher planting density at anthesis, while root pruning
significantly (P<0.05) reduced the root biomass in the upper 40 cm of soil, but
increased the root biomass and the proportion of root biomass in the 80-120 cm soil
layer.
4. The effect of population structure by seeding rate and root pruning. In experiment 2,
higher seeding rates led to higher LAI. However in 2008 seeding rate had no  significant effect on LAI. The total number of tillers (fertile tillers: those with a head
and infertile tillers: those without a head) per unit area increased linearly with seeding
rate whereas the number of tillers per plant decreased, and the spiker density did not
affect by seeding rate. Two root pruning treatments increased the values of LAI in both
seasons and decreased tiller density and the number of tillers per plant (P<0.05), but
had little effect on the number of fertile tillers (spikes).
5. The effect of the exchange of gases by seeding rate and root pruning. Water shortage
and increasing the planting density significantly decreased flag leaf photosynthesis and
photosynthetic activity, while root pruning significantly increased the photosynthetic
capacity of the flag leaf in pot experiment. In experiment 2, higher seeding rates
decreased the rate of flag leaf photosynthesis (Pn) and photosynthetic activity ,
increased the rate of root respiration (Rr), leading to a significant decrease in root
efficiency (Pn : Rr). In contrast, leaf photosynthetic rate increased and root respiration
rate decreased in the root pruning treatments, leading to a higher Pn : Rr ratio. It
indicated that the reducing of root biomass decreased the carbon consumed, leading to
more photosynthetic product was used to increase grain yield.
6. The effect of seeding rate and root pruning on competition ability of winter wheat was
invested using de Wit replacement series. In experiment 1, the relative yield of
unpruned plant was significantly higher than 1 while root pruning wheat was lower
than 1 in mixture. The relative total yield of normal density was 1.06 when water was
plentiful, which was significant greater than 1, indicated that unpruned plant was a
superior competitor, the mixture of unpruned plant and root pruning in normal density
could increase the grain yield significantly under the well watered condition.
7. Nitrogen and phosphorus use efficiency were researched in field experiment. The
nitrogen and phosphorus in leaves decreased with the seeding rate increased. Two root
pruning treatments had higher nitrogen and phosphorus content in leaves than that of
unpruned treatment. It suggested that the higher photosynthetic rate of root pruned
plant may associate with the higher nitrogen and phosphorus content in leaves.
8. In experiment 2, both post-heading dry matter accumulation and translocation
significantly increased with seeding rate. In W and S, post-heading dry matter
accumulation significant higher than unprunned plants. Post-heading dry matter accumulation was very important for increasing grain yield, it suggested that the
greater grain yield of root pruning plants may associate with the higher post-heading
dry matter accumulation.
In presednt study, increasing seeding rate and root pruning treatments can increase
grain yield and water use efficiency in average-rainfall years on the semi-arid Loess
Plateau. The greater grain yield in higher seeding rate derived from higher spike density
and grain number per unit. While root pruning reduced the water consumption before
anthesis, more soil water used for grain filling, and increased water use efficiency.
Meanwhile, root pruning reduced the infertile tillers, improved the canopy structure,
decreased the useless carbon consumed, and increased the post-heading dry matter
accumulation, and resulted in higher grain yield. However, the competition of soil water in
winter wheat increased due to increasing seeding rate and led to decreased grain yield in
severe drought years. In conclusion, it is hopeful that improved grain yield and water use
efficiency by increasing seeding rate and root pruning in arid or semi-arid areas.
Key words: Winter wheat (Triticum aestivum), Grain yield, Water use efficiency,
Semi-arid Loess Plateau, Competition ability, Root efficiency

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8905
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
方燕. 密度和根修剪对冬小麦产量及水分利用效率的影响[D]. 北京. 中国科学院研究生院,2010.
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