Effects of Soil Moisture on Dynamic Distribution of Dry Matter Between Winter Wheat Root and Shoot

The dynamic relationship of dry matter accumulation and distribution between winter wheat root and shoot was studied under different soil water conditions. The dry matter accumulation in root was greatly influenced by water stress, so as to the final root weight of the treatment with 40% field moisture capacity(FMC) was less than 1/4 of that of the treatment with 80% FMC on average. Water stress during the 3-leaf stage to the tillering stage had the greatest influence on root, and the influence of water stress during the jointing stage to the booting stage on shoot was greater than root. However, water stress during the tillering stage to the booting stage had a balanced effect on root and shoot, and the proportion of dry matter that distributed to root and shoot was almost the same after rewatering. Water recovery during the jointing stage to booting stage could promote R/S, but the increasing degree was related to the duration of water limitation. Soil water condition had the lowest effect on R/S during the flowering stage to the filling stage and the maximal effect on R/S during the jointing stage to the heading stage, R/S of 40% FMC treatment was 20.93 and 126.09% higher than that of 60% FMC and 80% FMC treatments respectively at this period.

The Equilibrium and Growth Stability of Winter Wheat Root and Shoot Under Different Soil Water Conditions

The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at whole growth phase, moderate deficiency irrigation at whole growth phase, serious deficiency irrigation at whole growth phase, sufficient irrigation at jointing stage, tillering stage, flowering stage, and fillering respectively, after moderate and serious water deficit during their previous growth stage. Root and shoot biomass were measured. On the basis of the cooperative root-shoot interactions model, the equilibrium and growth stability were studied on the strength of the kinetics system theory. There was only one varying equilibrium point between the root and shoot over the life time of the winter wheat plant. Water stress prolonged the duration of stable growth, the more serious the water deficit, the longer the period of stable growth. The duration of stable growth was shortened and that of unstable growth was prolonged after water recovery. The growth behavior of the plants exposed to moderate water deficit shifted from stable to unstable until the end of the growth, after rewatering at flowering. In the life-time of the crop, the root and shoot had been adjusting themselves in structure and function so as to maintain an equilibrium, but could not achieve the equilibrium state for long. They were always in an unbalanced state from the beginning to the end of growth. This was the essence of root-shoot equilibrium. Water stress inhibited the function of root and shoot, reduced root shoot interactions, and as a result, the plant growth gradually tended to stabilize. Rewatering enhanced root shoot interactions, prolonged duration of instable growth. Rewatering at flowering could upset the inherent relativity during the long time of stable growth from flowering to filling stage, thus leading to unstable growth and enhanced dry matter accumulating rate in the whole plant.

Cytological Correlation Between Flower and Vegetative Shoot Development from Immature Embryo-Derived Calli in Wheat

In this paper, the traits of immature embryo culture from 45 genotypes of bread wheat were investigated in detail, and trait correlation analysis in combination with histomorphological examination was used to study the cytological origin of flower as well as the correlation between it and vegetative shoot development from the calli. The rate of floral development in the subculture was highly significantly and positively related to that of the differentiation culture, which reveals that the genetic system of floral development from immature embryo-derived calli in wheat was highly correspondent and stable. The rate of floral development was related neither to the traits in the dedifferentiation culture, nor to the vegetative shoot formation from the total induced calli, but significantly and positively related to that of the calli without leaf-like green spots in the differentiation culture. These findings indicate the partial correlation as well as differentiation between flower and vegetative shoot development. The floral development might only be associated with the genetic system controlling organ regeneration, while vegetative shoots formed from the two ways, including somatic embryogenesis and organ regeneration.

The Wheat Plastochron Mutant, fushi-darake, Shows Transformation of Reproductive Spikelet Meristem into Vegetative Shoot Meristem

In wheat plants at the vegetative growth stage, the shoot apical meristem (SAM) produces leaf primordia. When reproductive growth is initiated, the SAM forms an inflorescence meristem (IM) that differentiates a series of spikelet meristem (SM) as the branch. The SM then produces a series of floret meristem (FM) as the branch. To identify the mechanisms that regulate formation of the reproductive meristems in wheat, we have investigated a leaf initiation mutant, fushi-darake (fdk) which was developed by ion beam mutagenesis. The morphological traits were compared in wild type (WT) and fdk mutant plants grown in the experimental field. WT plants initiated leaves from SAM at regular intervals in spiral phyllotaxy, while fdk plants had 1/2 alternate phyllotaxy with rapid leaf emergence. The fdk plants have increased numbers of nodes and leaves compared with WT plants. The time interval between successive leaf initiation events (plastochron) was measured in plants grown in a growth chamber. The fdk plants clearly show the rapid leaf emergence, indicating a shortened plastochron. Each tiller in fdk plants branches at the upper part of the culm. The fine structure of organ formation in meristems of fdk plants was examined by scanning electron microscopy (SEM). The SEM analysis indicated that fdk plants show transformation of spikelet meristems into vegetative shoot meristems. In conclusion, the fdk mutant has a heterochronic nature, i.e., both reproductive and vegetative programs were simultaneously in operation during the reproductive phase, resulting in a shortened plastochron and transformation of reproductive spikelets into vegetative shoots.

Physiological Responses of Two Wheat Cultivars to Nitrogen Starvation

Plants need to be efficient in nutrient management, especially when they face the temporal nutrient defficiencies. Understanding how crops respond to nitrogen （N） starvation would help in the selection of crop cultivars more tolerant to N deficiency. In the present work, the physiological responses of two wheat cultivars, Yannong 19 （YN） and Qinmai 11 （QM）, to N starvation conditions were investigated. The two cultivars differed in biomass and N rearrangement between shoots and roots during N starvation. QM allocated more N to roots and exhibited higher root/shoot biomass ratio than YN. However, tissue measurement indicated that both cultivars had similar nitrate content in leaves and roots and similar remobilization rate in roots. Microelectrode measurement showed that vacuolar nitrate activity （concentration） in roots of QM was lower than that in roots of YN, especially in epidermal cells. Nitrate remobilization rates from root vacuoles of two cultivars were also identical. Moreover, vacuolar nitrate remobilization rate was proportional to vacuolar nitrate activity. During N starvation, nitrate reductase activity （NRA） was decreased but there were no significant differences between the two cultivars. Nitrate efflux from roots reduced after external N removal and QM seemed to have higher nitrate efflux rate.

Effect of Plant Derived Smoke on Germination and Post Germination Expression of Wheat (Triticum aestivum L.)

Smoke produced from burning of plant material elicits a striking increase in seed germination in various plant species. In present work, effect of plant derived smoke exposure on wheat (Triticum aestivum L.) seeds germination and post germination response has been studied in laboratory. Plant derived smoke was generated by burning of plant material (leaf, straws etc.) in a special designed furnace. Non-imbibed and imbibed seeds of wheat were exposed to plant derived smoke for 1 hr time duration. Best results were observed in non-imbibed seeds treated with plant derived smoke while imbibed seeds showed poor response to germination percentage, germination index, seedling vigor index and root shoot length. It has been proved from present study that plant derived smoke has stimulatory effect on germination & post germination response of non-imbibed seeds while it may cause inhibitory effect in imbibed seeds of wheat.

灌水和施氮对冬小麦根系特征及氮素利用的影响

植株根系的形态和生理特性决定着其获取养分和水分的能力,分析麦田冬小麦根系形态特征、根系活力对水氮的响应及其与地上干物质积累、产量和氮素利用的关系,有利于构建合理的冬小麦根群结构,促进根冠协调生长并提高氮肥利用效率。在麦田定位试验基础上,采用裂区试验设计,设置2个灌溉主处理(W0:全生育期不灌水、W1:拔节期和开花期各灌水1次)以及3个施氮副处理(N0:0 kg hm^(–2)、N180:180 kg hm^(–2)和N300:300 kg hm^(–2))。结果表明:与W0处理相比,W1抑制根长密度的增加,但增加根系平均直径,提高0~20 cm土层根表面积和根干重密度,显著提高根系活力4.98%~22.7%,降低根冠比1.47%~11.25%;2年平均小麦产量、氮素吸收效率和氮肥偏生产力分别提高15.50%、13.40%和14.91%。施氮促进根系生长,与不施氮处理相比,施氮显著提高根系平均直径、根长密度、根表面积、根干重密度和根系活力,降低根冠比。其中N180更有利于根系生长,提高冬小麦根系各形态指标和根系活力,与N300相比,2年平均产量提高2.53%,而氮素吸收效率和氮肥农学效率分别显著提高44.51%和39.37%。相关分析表明,拔节期至开花期根干重密度与产量、氮利用率呈显著正相关关系;根冠比与产量呈显著负相关关系,与氮利用率呈正相关关系。因此,合理的灌水和施氮能够优化根系形态及分布,提高根系活力,协调根冠干物质分配,提高产量和氮利用率。在冬小麦生产中拔节和开花期各灌水1次结合180 kg hm^(–2)施氮量有利于促进产量和氮素利用效率协同提高。

不同土壤水分处理对冬小麦根冠生长的影响

通过温室冬小麦不同水分处理(土壤含水量分别为田间持水量的75%～100%,65%～55%,35%～45%)盆栽试验,研究了冬小麦根冠对水分的响应。试验结果表明:不同供水量并不影响冬小麦根系、冠层干物质累积过程的总趋势,但随胁迫的增强,根、冠干物质累积速率、干物质累积总量降低,且二者并不呈线性相关关系;根冠比(R/S)随胁迫的增强而增大;水分供应量的减少缩短了冬小麦的生育周期,随胁迫的增强,根冠生物量最大值出现的时间提前;充分供水的处理则有最大的根冠比(R/S)。这可能是由于水分胁迫发生,大量的同化产物运往根系,分配于根系的同化干物质增加,调整了根系的结构,改善其功能以增大水分的吸收量,缓减植株由于缺水造成的损失,导致根系干重增加,根冠比增加。对于供水超过75%的植株,根冠比达到所有处理的最大,可能原因为过量水分促使庞大根系的建成,从而消耗较多的同化产物,使根重增加,冠重减少。

小麦芽生长点的基因枪转化技术研究

为建立简易的不依赖组织培养和抗性筛选的小麦转基因技术,以小麦品种石4185为对象,以gus和badh/bar为外源基因,围绕适于基因枪转化的种子芽生长点受体的制备、基因枪轰击参数的优化等开展了试验,建立了＂用解剖刀去除种子根、用镊子把芽鞘掰去、用镊尖扫去包盖生长点的未展开叶、将带生长点的部分与胚乳分离＂为特点的受体制备方法;确定1100 Psi＋9 cm为最佳轰击参数组合。对轰击后的小麦芽生长点（70个×3批）进行gus基因瞬时表达检测,以受体数统计时,转化率为22.9%-35.7%;以生长点数统计时,转化率为5.7%-8.6%。用含badh/bar的pABH9质粒转化1000个受体,发育成了802个T0植株,对T0植株所结种子长成的穗行喷200 mg/kg的PPT进行抗性筛选,获得了105个抗性株,究其来源为42个T0株,由此计算抗性率为5.2%。用PCR检测T1植株,6个呈阳性。初步建立了基因枪法转化小麦种子芽生长点的技术。

土壤水变动对冬小麦生长产量及水分利用效率的影响

采用盆栽和管栽试验,研究土壤水变动对冬小麦地上部生长、产量及水分利用效率的影响。结果表明:株高对水分胁迫的发生时期较敏感,叶面积对水分胁迫的持续时间更敏感,与其他水分胁迫处理相比,分蘖至拔节阶段水分胁迫处理的株高最小,分蘖至孕穗阶段水分胁迫处理的叶面积最小。冠重主要受胁迫持续时间的影响,分蘖至孕穗阶段水分胁迫处理的冠重最小。水分胁迫对冬小麦穗数和WUE的影响基本上表现为正效应,而对每穗粒数、千粒重及产量的影响则全部为负效应。在各水分胁迫处理中,拔节至孕穗阶段经中度水分胁迫后抽穗期复水的处理,产量最高,达到充分供水对照的62%;分蘖至拔节阶段经中度水分胁迫后孕穗期复水的处理,WUE最大。试验结果表明,冬小麦株高、叶面积及各产量要素对土壤水变动的响应存在差异。

小麦茎顶端原基发育模拟模型的研究

本文系统地模拟了小麦植株茎顶端不同类型原基的发育过程 ,建立了叶原基分化、小穗原基分化和小花原基分化、退化、败育、受精结实及籽粒生长的子模型。模型引入每小穗分化的最大小花原基数、退化的最大小花原基数和籽粒潜在重量 3个遗传参数 ,分别反映了不同小麦品种小花分化、退化和籽粒生长等方面的遗传差异。利用南京地区两组田间试验资料对所建模型进行了检验 ,表明模型对小麦叶原基分化、小穗原基分化和小花原基的分化、退化、败育、受精结实以及籽粒重等均有较好的预测性和适用性 ,其平均差平方和的根值均小于 2。

土壤水分对冬小麦根、冠干物质动态消长关系的影响

在不同供水条件下 ,研究了冬小麦根、冠干物质积累的动态消长关系。结果表明 ,在水分胁迫条件下 ,冬小麦根系的干物质积累受到了明显的影响 ,40 %田间持水量处理植株的最终根重平均不到 80 %田间持水量处理的1/ 4。三叶期至分蘖期水分胁迫对根的抑制作用最大 ,拔节期至孕穗期水分胁迫对冠的抑制作用大于根 ,从分蘖期开始并延续到孕穗阶段的水分胁迫对根和冠的抑制作用较均衡 ,复水后干物质向根系和冠层的分配比例近似。拔节期至孕穗期复水对根的促进作用大于冠 ,干物质向根分配的比例增加 ,R/S提高 ,但提高的程度与复水前水分胁迫的历时有关。水分条件对冬小麦R/S值影响最小的时期是开花期至灌浆期 ,最大的时期是拔节期至抽穗期 ,此阶段 40 %田间持水量处理的R/S分别比 60 %和 80 %田间持水量处理提高 2 0 .93 %和 12 6.0 9%。

麦秆、油菜秆还田腐解速率及养分释放规律研究

采用尼龙网袋法直接覆盖还田和组织结构切片方法,研究了麦秆、油菜秆还田后的腐解速率及养分释放规律。结果表明,麦秆、油菜秆还田后,腐解速率均表现为前期快,后期慢。试验期间(100 d),麦秆、油菜秆的累计腐解率分别为66.18%和55.62%;养分释放均为钾>磷>氮。麦秆、油菜秆还田前10 d内,钾的释放分别达到98.92%和98.74%。在麦秆腐解过程中,前50 d未见任何明显的结构破坏;50 d后,组织结构的破坏主要发生在基本组织的薄壁细胞及其所包围的维管束,表皮和机械组织以及其所包围的维管束的破坏仍不明显。在油菜秆腐解过程中,组织结构的破坏主要发生在腐解的前10 d,次生木质部以上的维管形成层、韧皮纤维、皮层薄壁组织和表皮均受到破坏而脱落。结果说明,秸秆中的钾是水可浸提的,为速效钾,作物推荐施肥量中可减去所用秸秆的钾含量;由于秸秆中氮、磷含量较低,特别是磷,因此在还田初期可不考虑调整氮、磷肥用量。

TDZ预处理及激素诱导对小麦茎尖丛生芽形成的影响

为了给遗传转化提供更好的受体,从而降低离体芽转化直接成苗出现的嵌合体现象,以4个普通小麦品种(系)为材料,研究了小麦籽粒细胞分裂素TDZ(噻二唑苯基脲)浸泡预处理及激素对小麦茎尖丛生芽形成的影响。结果表明,TDZ浸泡预处理降低了小麦胚萌发率,但显著提高了小麦茎尖丛生芽的分化,在TDZ最佳浓度5mg·L-1时,4种供试小麦材料的丛生芽诱导率和平均芽个数均达到最高,其中扬麦18最优,丛生芽诱导率和平均芽个数分别达到了50.9%和2.82个;萌发培养基中的TDZ浓度为4mg·L-1时,小麦茎尖丛生芽的诱导率和平均芽个数最高;诱导培养基中TDZ和6-BA(6-苄基脲嘌呤)浓度均为3mg·L-1时,诱导小麦丛生芽的效果最佳,并且TDZ诱导效果优于6-BA;细胞分裂素与生长素配合诱导时,在TDZ/IAA(吲哚乙酸)为6、6-BA/2,4-D(2,4-二氯苯氧乙酸)为60时,诱导效果较好,但低于细胞分裂素单独诱导的效果,且随着比值的进一步增大,其诱导效率急速下降;同时基因型对小麦茎尖丛生芽诱导有重要影响,供试的4个材料中,扬麦18的丛生芽诱导率最高,扬麦12次之,西农183、小偃22较差。

水氮调控对冬小麦根冠比和水分利用效率的影响研究

通过田间和桶栽试验研究了水、氮调控对冬小麦根冠比和水分利用效率的影响。田间试验结果显示,土壤水分条件对冬小麦根冠生长影响显著。当冬小麦生育期60 cm土层土壤水分维持在田间持水量的60%以上时,根冠比维持稳定状态,不随灌溉次数的增加而变化;当冬小T麦生育期60 cm土层土壤水分低于田间持水量的60%时,土壤越干旱,根冠比越大。桶栽试验结果显示,氮素水平对冬小麦根冠比影响显著,而水氮互作效应对根冠比影响不显著。在所有水分处理条件下,随着施氮量增加,冬小麦根量减少。施氮对冬小麦地上部分和地下部分的影响不同。在水分亏缺条件下,随着氮用量增加,冬小麦经济产量呈增加趋势,水分利用效率与施氮量存在明显正相关关系;而在充分灌溉条件下,产量随着施氮量的增加表现出先增加后降低的趋势,存在一个氮肥用量阈值。因此,水氮通过调控地上地下干物质分配而影响作物产量和水分利用效率,在水分供应受限制条件下,增施氮肥会降低根冠比,更利于地上干物质的积累和经济产量形成。田间试验和桶栽试验均表明,冬小麦根冠比与水分利用效率呈负相关,根冠比大不利于地上部分干物质的积累和作物产量的形成,导致水分利用效率降低。

水分胁迫持续时间对冬小麦根冠生物量累积的影响

为了解冬小麦根、冠对土壤含水量变化的响应，对不同水分条件下温室盆栽冬小麦作了分析研究。该试验包括七个水分状态，充分供水A处理（75％～100％FC，FC为田间持水量），中度胁迫B处理（55％～65％FC）和重度胁迫C处理（35％～45％FC）以及分蘖期开始中度、重度胁迫到孕穗期复水的BA1、CA1处理和抽穗期复水的BA2、CA2处理。试验结果表明：分蘖期开始的水分胁迫无论何时恢复供水都不影响冬小麦根、冠生长过程的总趋势；但随胁迫程度、胁迫持续时间的增加。胁迫期内根、冠的相对生长率。根、冠总重均降低。但根重占有量增大。且水分供应量的减少和胁迫时间的延长使冬小麦生育周期提前结束；随胁迫的增加，胁迫时间的延续，最大根重减小。但较大根重维持的时间延长；当复水后。各处理对复水存在不同程度的滞后效应和激发补偿生长。导致短期胁迫的根重占有量小于长期胁迫处理，中度胁迫小于重度胁迫，冠重也随之改变。造成此现象的原因：水分胁迫影响植株的功能。但自适应能力的作用促使分配于根系的同化物质增加，改善和提高根系的吸水能力。缓减植株由于缺水造成损失；对于供水超过75％FC的植株，生育后期的冠重占有量较小。根重较大则归因于生长过程已形成的庞大根系。

水分胁迫对冬小麦根、冠生长关系及产量的影响

以冬小麦品种北农 10号为材料 ,研究了水分胁迫效应对作物根、冠生长关系及产量的影响。结果表明 ,冬小麦根、冠间存在异速生长关系 ,导致根冠比随植株发育进程而呈指数下降。根、冠间的这种异速生长关系可用模型y =a +bx表示 ,y代表根干重的自然对数 ,x代表冠干重的自然对数 ,a为截距 ,b为线性回归系数。水分条件不足时 ,b值减小 ,根、冠的异速生长明显 ;水分胁迫后复水 ,b值增加 ,根、冠生长的异速性减小 ,趋于协调。在本试验条件下 ,水分胁迫对冬小麦穗数的影响基本上表现为正效应 ,而对每穗粒数、千粒重、产量及WUE的影响则全部为负效应。在各水分胁迫处理中 ,拔节至孕穗阶段中度水分胁迫抽穗期复水的冬小麦 ,由于受胁迫时间较短 ,因而产量最高 ,达到充分供水对照的6 2 %。

西南麦区高产多穗型小麦单株分蘖特征研究

为探究西南麦区特殊生态环境下高产多穗型小麦单株分蘖出现规律、成穗规律及其与产量形成的关系,以3种穗型小麦为试验材料,采用田间调查、室内体视解剖观察和间接酶联免疫吸附(ELISA)等方法,分别对单株分蘖出现时间和茎顶端生长进行了调查统计,对茎蘖内源赤霉素(GAs)、吲哚乙酸(IAA)、分裂素(ZR)、脱落酸(ABA)和玉米素(ZT)的含量进行了测定,比较分析了以上因素与分蘖穗部性状的关系。结果表明,与大穗型和中间型小麦相比,高产多穗型小麦单株分蘖平均出现时间(7.41d)和相邻分蘖发生的平均间隔时间(2.66 d)最短;相邻分蘖顶端原基生长阶段均差(1.10)最小。相邻分蘖的GAs、IAA、ZR和ABA含量平均差值最小,分别为0.59、1.01、0.13、8.73 ng·g-1FW;二级分蘖的IAA/ABA(0.65)和ZR/ABA(0.08)最高,IAA/(ZR+ZT)(1.06)最低,3个比值与一级分蘖的相关比值差距最小。相邻分蘖穗部结实性状的平均差值最小,分别为穗粒数1.69、单穗平均粒重2.31mg、不孕小穗数0.87和结实小穗数1.61;单株成穗率(87.50%)和单株平均粒重(23.75g)最高。综上,在3种穗型小麦中,多穗型小麦单株各分蘖的出现和生长存在着更为均匀的协调关系,使得分蘖成穗较高,这有利于西南麦区特殊生态环境下单株产量因子的合理构成和突破性品种的选育。

保水剂对冬小麦生长及水分利用效率的影响

为阐明保水剂对不同生育阶段作物的生长及水分利用等的影响,选择小麦品种郑麦9694和矮抗58通过大田试验,研究了不同用量保水剂(0,30,60,90 kg/hm2)对2个冬小麦生长过程中各生育期阶段的群体变化、株高、叶面积、根冠比及与产量和水分利用效率等作用特征。结果表明:施用保水剂提高了各生育期冬小麦的总群体数、株高和叶面积,各项指标均高于对照。除90 kg/hm2处理外,均随其用量的增加群体数增加,尤其在拔节期和灌浆期,且郑麦9694的增加幅度较矮抗58高,特别是60 kg/hm2处理;株高表现为郑麦9694>矮抗58,且在孕穗期郑麦9694较矮抗58株高增幅大,而在拔节期和灌浆期,结果相反;郑麦9694在各生育期的叶面积均低于矮抗58,但保水的施用使其叶面积增幅较矮抗58大。各生育期的根冠比表现为:拔节期>孕穗期>灌浆期、收获期,且郑麦9694的根冠比均小于矮抗58。郑麦9694在拔节期各处理的根冠比均显著低于矮抗58,但随小麦生育期的推进,施用保水剂处理的根冠比差异减小。施用保水剂减少了小麦的总耗水量,提高了冬小麦产量、千粒重及水分利用效率,且郑麦9694千粒重和产量及水分利用效率(30 kg/hm2除外)高于矮抗58,且2个品种均以保水剂用量为60 kg/hm2时的效果较佳。

水分胁迫下小麦地上和地下部的反应及其抗旱性研究

本试验较系统地研究了四个小麦品种（科遗２６、４４２Ｍ－１、山农２１５９５３、中国春）水分胁迫下地上、地下部的形态、生理和信息传递物质的变化及其抗旱性，为高等植物的抗旱机理研究提供了一些有价值的资料．为抗旱育种和旱农栽培提供理论上的依据。