Otoplasty: sequencing the operation for improved results

LEARNING OBJECTIVES:: After studying this article, the participant should be able to: 1. Understand the anatomy and embryology of the external ear. 2. Understand the anatomic causes of the prominent ear. 3. Understand the operative maneuvers used to shape the external ear. 4. Be able to sequence the otoplasty for consistent results. 5. Understand the possible complications of the otoplasty procedure. Correction of prominent ears is a common plastic surgical procedure. Proper execution of the surgical techniques is dependent on the surgeon's understanding of the surgical procedure. This understanding is best founded on an understanding of the historical bases for the operative steps and the execution of these operative steps in a logical fashion. This article describes the concept of sequencing the operation of otoplasty to produce predictable results combining the technical contributions from many authors. The historical, embryological, and anatomic bases for the operation are also discussed. Finally, the authors' preferred techniques are presented. Sequencing the steps in the preoperative assessment, preoperative planning, patient management, operative technique, and postoperative care will produce reproducible results for the attentive surgeon. Careful attention to the details of the operation of otoplasty will avoid many postoperative problems.     

Combined otoplasty technique: chondrocutaneous conchal resection as the cornerstone to correction of the prominent ear

The failure to correctly analyze the complex deformity that comprises the prominent ear is the most common cause of the undesired surgical result. Recognizing conchal hypertrophy as one of the leading causes of the prominent ear deformity has led to a versatile and reproducible otoplasty technique that is easily modified to the common side-to-side variation in deformity. From January of 1993 to August of 2000, chondrocutaneous conchal resection has been used as the cornerstone to a combined sequence of maneuvers in otoplasty. The operation was performed on 47 patients (40 bilateral cases and 7 unilateral), and the total number of ears operated on was 87. There were three complications requiring revision surgery, and follow-up periods ranged from 6 months to 7 years, with all patients achieving a satisfactory result. Detailed methods of chondrocutaneous conchal resection along with the sequence of the authors' combined otoplasty techniques are presented.     

Prominent ears in children younger than 4 years of age: what is the appropriate timing for otoplasty?

The present study was conducted to determine whether otoplasty performed in children younger than 4 years of age has an acceptable long-term outcome. This two-part study consisted of (1) a questionnaire mailed to 481 members of the American Association of Plastic Surgeons to ask their opinion on the timing of otoplasty, and (2) a consecutive series of 12 patients who had otoplasty performed before the age of 4 years. The survey demonstrated that the majority (57 percent) of the respondents perform otoplasty on patients who are aged 5 years or older. The prospective series consisted of 12 patients ranging in age from 9 months to 3 years at the time of the procedure. Otoplasty was bilateral in nine patients and unilateral in three patients. Length of follow-up ranged from 21 months to 7(1/2) years, with a median follow-up of 41 months. Growth following otoplasty was evaluated in three patients who underwent unilateral otoplasty by measuring the length of both ears at the time of final follow-up. No difference in ear length was noted between the sides that were and were not operated on during a follow-up period of 46 to 63 months. Noticeable recurrence was noted in only one (8 percent) of 12 patients. In response to a follow-up questionnaire to the patients' families, all respondents (n = 10) stated that if again asked to choose the timing of otoplasty in their children, they would opt to have it performed at the same age of younger than 4 years. Otoplasty can be safely performed at ages younger than previously thought without interfering with growth of the operated ear.     

Ear reduction with or without setback otoplasty

Ear reduction has been performed occasionally for aesthetic considerations. This series is comprised of 8 patients representing 7 bilateral reductions and 1 unilateral reduction for a total of 15 ears. Historically, surgery for macrotia consisted of resections of full-thickness wedges from the periphery of the ear. The surgical defect was repaired by directly approximating the wound edges. Additional removal of triangular or crescent-shaped segments from adjacent sides of the wound prevented the cupping of the reconstructed ear. Secondary deformities were not uncommon consequences. The most distressing were cruciform scars that defaced the lateral surface of the ear. These were frequently exacerbated by the uneven coaptation of the underlying cartilages. The current technique places the incisions at strategic locations where the scars that form are less conspicuous. The initial steps are essentially identical with the lateral transhelical approach to otoplasty for protruding ears. In some patients, both procedures have been combined during the same operative session.     

Understanding the unfavorable result after otoplasty: an integrated approach to correction

The correction of an unfavorable outcome after otoplasty requires a thorough understanding of the anatomy of prominent ear and recognition of the spectrum of secondary deformities and their origin. The goal of this article is to describe the causes of postotoplasty deformity, including both undercorrection and overcorrection. The latter presents the more complicated reconstructive problem, as both skin shortage and permanent cartilage disruption need to be addressed. The authors propose an algorithm for revision otoplasty based on clinical findings and patient concerns. Finally, a case with overcorrection secondary to both skin deficiency and cartilage disruption is illustrated showing the sequential steps needed for optimal correction.     

Otoplasty: anterior scoring technique and results in 500 cases

Corrective otoplasty is a commonly performed procedure to change the shape of the auricular cartilage. Many techniques use permanent sutures to maintain the cartilage folding, whereas other techniques rely on cartilage incisions (partial thickness or full thickness). At this institution, a cartilage cutting and anterior scoring technique has been used for more than 30 years with pleasing results. The surgical techniques published in the past have been reviewed and compared with the procedure used at this institution to point out the advantages, disadvantages, and differences of these various techniques. Also reviewed were 500 consecutive cases operated on under local or general anesthesia between January of 1993 and December of 1995 to determine the incidence of early and late complications. The patients were contacted by mail to return for a follow-up examination or answer a questionnaire, at least 2 years after the procedure. Early complications were bleeding in 13 cases (2.6 percent) and hematoma in 2 cases (0.4 percent). There were no infections or ear necrosis. A small cutaneous wound was present on the anterior skin in three patients (0.6 percent), and there was one wound dehiscence (0.2 percent). Late complications were keloids in two cases and inclusion cysts in three cases. Residual deformity was noted in 22 cases and asymmetry in 28 cases. Secondary surgery was performed in six cases. The questionnaire was answered by 387 patients (77.4 percent response rate): pain when the ear is touched was present in 22 cases (5.7 percent), hypesthesia in 15 cases (3.9 percent), occasional cutaneous irritation in 38 cases (9.8 percent), asymmetry in 71 cases (18.4 percent), and abnormal ear shape in 17 cases (4.4 percent). Twenty-nine patients (7.5 percent) also noted that the ear was more sensitive to cold or touch. The satisfaction rate was 94.8 percent: very satisfied, 74 percent; satisfied, 20.8 percent; dissatisfied, 4.2 percent; and very dissatisfied, 1 percent. These results were compared with other published series of complications and late results after otoplasty; the complication rates are similar or lower in this study. Therefore, it can be concluded that the cartilage cutting and anterior scoring technique otoplasty is a safe procedure with a high patient-parent-surgeon satisfaction rate.     

Production of huitlacoche, Ustilago maydis: timing inoculation and controlling pollination

Huitlacoche is the name given to young, fleshy, edible galls that form when ears of Zea mays are infected by Ustilago maydis. Huitlacoche is processed and sold fresh at markets in Mexico. Interest has increased recently in producing U. maydis as a specialty mushroom in the United States. Silk-channel inoculation methods developed to evaluate common smut resistance in maize can be used to produce huitlacoche commercially. This research assessed the effects of time of inoculation and preventing pollination on the severity of ear galls and yield of huitlacoche produced by inoculating silks with U. maydis. Yield of huitlacoche and severity of ear galls were closely related, as was evident from highly significant linear or curvilinear regressions. Severity and yield were greatest when ears were inoculated 4-8 d after the mid-silk growth stage. Ear galls were 5-15% more severe and yield of huitlacoche was 18-150% greater on ears that were not pollinated, compared to those that were pollinated. Maximum yield of huitlacoche was 131 g ear(-1) from unpollinated male-sterile field corn inoculated 6 d after the mid-silk growth stage and 92 g ear(-1) from detasseled sweet corn inoculated 6 d after mid-silk. About 25% of the total weight of ears consisted of marketable huitlacoche when yields were highest. Quality of huitlacoche was not affected by time of inoculation or pollination treatments, but quality of huitlacoche harvested 12-14 d after inoculation was unacceptable primarily due to lack of teliospores, which affected color and flavor.     

Survival of Tillers and Distribution of Dry Matter between Ear and Shoot of Barley Varieties

Plants of Plumage Archer barley grown in pots produced moreshoots than did Proctor, but had fewer ears at maturity, becausesome shoots died about 7 days before ear emergence. The numberand position on the plant of the shoots that died were consistentfor particular growing conditions. Shoots that died were notalways the last to be produced. There were no consistent differencesin dry weight, leaf area, nitrogen content, or apex developmentbetween shoots that did and did not survive; nor did removingthree developing ears on older shoots affect the survival ofother shoots. Growth of Plumage Archer plants was not checkedby death of shoots; dry matter, nitrogen, and leaf area wereredistributed so that increase in surviving shoots compensatedfor losses in the dead shoots. The dry-weight ratio of ear to shoot was smaller for Proctorthan for Plumage Archer at ear emergence and anthesis, but atmaturity it was greater for Proctor, both when ears were shadedto prevent them photosynthesizing and when they were unshaded.The varietal difference in ear: shoot dry-weight ratio was reversedbecause the relative growth-rate of ears of Proctor was greaterand because more dry matter was lost from its shoots. Both changesmay have been caused by translocation to the ear of a greaterproportion of the assimilate from the shoots of Proctor thanof Plumage Archer. Leaves of Proctor appeared to be more efficientin producing dry matter for the ear than those of Plumage Archer.     

Some treatments affecting growth substances in developing wheat ears

Cytokinin, auxin and gibberellin-like substances were bio-assayed in extracts from developing ears of wheat plants grown in various conditions. Changes in cytokinin activity along the ears may be related to the earlier flowering in the middle of the ear. Ears on the main stems of plants from which all the tillers had been removed contained less cytokinin than the main-stem ears of normal tillered plants. When grain development was stopped by preventing fertilization of the ovules the ear contained more cytokinin than normal ears. With de-tillered plants, removing flag leaves before anthesis increased cytokinin, gibberellin and auxin in the ears; later removal of flag leaves did not affect cytokinin but decreased gibberellin in the ears. Conversely, removing ears before anthesis did not affect cytokinin or auxin in the flag leaves, but their gibberellin was less than that of flag leaves on intact plants. Treatment of wheat ears with zeatin did not affect grain weight or number per ear which supports the conclusion that the growth substances in the ear may be adequate for normal grain growth.     

Homeotic Sexual Translocations and the Origin of Maize (Zea Mays, Poaceae): A New look at an old problem

In the Origin of Maize Controversy, the Orthodox Teosinte Hypothesis (OTH; Beadle 1939, 1972; Iltis 1971), five key mutations change 2-ranked (distichous) ears of teosinte (wild Zea) with a single row of grains per rank to 4- to many-ranked (polystichous) maize ears with a double row of grains per rank. BUT teosinte ears are lateral to the 1° branch axes, maize ears, like their male homologues, the teosinte I° branch tassel spikes, terminal, an enigma long unrecognized, hence ignored. In the Catastrophic Sexual Transmutation Theory (CSTT; Iltis 1983b, 1987), now abandoned, the I° branch tassel (male) of teosinte (spikelets soft-glumed, paired, i.e., double-rowed per rank, as in maize ears), when brought under female hormonal control by branch condensation, becomes feminized into a maize proto-ear. BUT lateral ears should then have remained teosintoid (2-ranked, each rank with a single row of grains), yet are in fact double-rowed. Combining OTH and CSTT, the new Sexual Translocation Theory (STLT) is based on: first, the branching pattern of teosinte ear clusters (Cámara-H. & Gambino 1990), sequentially maturing, sympodially branching, typically Andropogonoid systems, called rhipidia (sing, rhipidium), where each higher order (younger) ear originates as a lateral branch of its lower order, earlier maturing predecessor; and second, on 3 or 4 key mutations [cupule reduction, softening of glumes, doubling of female spikelets], which, by projecting outward the grains, invited human domestication by making them accessible. Within each ear cluster, the earliest maturing, hence nutrient-monopolizing and largest ear would be selected, all younger ears, already nutrientinhibited, suppressed. As fewer, larger ears evolved, and branch internode condensation moved male tassels into female hormonal zones, homeotic conversions translocated female morphology to terminal male positions: first replacing each of the II° branch tassels, and ultimately the 1° branch tassel (male), with an ear (female). With this, now female structure in the apically dominant, hence most nutrient-demanding terminal position gradually suppressing all subsidiary ears on the 1° branch beneath it, mutations for polystichy (contingent on nutrient overload) were finally allowed to become expressed, and the multi-rowed maize ear (at first with an atavistic male tail) evolved. Favored by human selection, these increases in apical dominance by stepwise homeotic sexual conversions explain both archeological and morphological realities, but need to be harmonized with recent results of developmental genetics. Current evidence suggests that teosinte was first tended for its green ears and sugary pith by hunter-gatherers as an occasional rainy-season food in small “garden” populations away from its homeland, and not for its abundant grain-containing, hard fruitcases, which easily mass-collected but useless as food, are as yet unknown from the archeological record. A rare grain-liberating teosinte mutation (probably expressed in only one “founder” plant, a mazoid “Eve”), which exposed the encased grain for easy harvest, was soon recognized as useful, collected and planted (or self-planted). Thus maize was started on its way to a unique horticultural domestication that is not comparable to that of the temperate Old World mass-selected agricultural grains.     

Early inflorescence and floral development in Zea mays land race Chapalote (Poaceae)

Tassel and ear primordia were collected from greenhouse-grown specimens of the Mexican maize landrace Chapalote and prepared for scanning electron microscopic (SEM) examination. Measurements of inflorescence apices and spikelet pair primordia (spp) were made from SEM micrographs. Correlation of inflorescence apex diameter with number of spikelet ranks showed no significant difference between tassels and ears, except at the two-rank level where the ear apical meristem had a significantly smaller diameter than corresponding two-ranked tassels. Within individual inflorescences, spp in different ranks enlarged at comparable rates, although the rates from one ear to the next along the stem differed. In both tassels and ears, spp divide to form paired sessile and pedicellate spikelet primordia when the spp is 150 μm wide; ear axes are significantly thicker than tassel axes at the time of bifurcation. The similarities in growth between ear and tassel primordia lend further support to the hypothesis that both the maize tassel and ear are derived from a common inflorescence pattern, a pattern shared with teosinte. Inflorescence primordial growth also suggests that a key character difference between teosinte and maize, distichous vs. polystichous arrangement of spikelets, may be related to size of the apical dome and/or rate of primordium production by the apical meristem. There appears to be more than a single morphological event in the shift from vegetative to reproductive growth. The evocation of axillary buds (ears) is independent of, and temporally separated from, the transition to flowering at the primary shoot apex (tassel).     

中耳胆脂瘤的影像诊断:高分辨率计算机断层成像与磁共振成像的比较研究

目的:评估和比较高分辨率计算机断层成像(high resolution computer tomography,HRCT)与磁共振成像(magnetic resonance imaging,MRI)对中耳胆脂瘤的诊断价值。方法:回顾性分析临床初步诊断为中耳胆脂瘤患者55人(63耳)在术前5天内进行的16排HRCT和1.5T MRI诊断结果,以病理诊断为基础对HRCT和MRI的诊断结果进行对比研究,统计分析HRCT和MRI的灵敏度、特异度、阳性预期值、阴性预期值,以及Kappa检验两者之间的内在观察一致性。结果:63耳中,病理确诊为中耳胆脂瘤40耳。HRCT正确诊断30例,假阳性11例,假阴性10例,灵敏度、特异度、阳性预期值以及阴性预期值分别为75%、52.17%、73.17%、54.55%。MRI正确诊断37例,假阳性和假阴性各为3例,灵敏度、特异度、阳性预期值以及阴性预期值分别为92.5%、86.96%、75%和86.96%。HRCT与MRI诊断结果之间的内在观察一致性Kappa=0.274(P0.05)。剔除既往有手术史的10耳,只针对无手术史的53耳,HRCT与MRI诊断结果之间的内在观察一致性增高,吻合度一般,Kappa=0.462(P0.05)。结论:MRI的总体阳性检出率高于HRCT,尤其是对中耳胆脂瘤手术后复发的诊断;HRCT与MRI两者相结合对于中耳胆脂瘤的明确诊断具有互补作用。     

Reproductibilité interobservateur d'un tympanomètre portatif,le MicroTymp.

OBJECTIVE: To determine the interobserver reliability of tympanograms obtained with the MicroTymp, a portable tympanometer. SETTING: Family medicine teaching unit in a tertiary care hospital. PATIENTS: Thirty-three patients who presented to the ear, nose and throat clinic in August 1990 for an ear problem. INTERVENTION: Three residents in family medicine independently attempted to record with the MicroTymp one tympanogram for the 66 ears. We excluded the results for seven ears for which tympanograms could not be obtained. MAIN OUTCOME MEASURE: Using objective criteria, two family physicians and two residents in family medicine independently classified the 177 tympanograms into five categories (normal, possible effusion, possible perforation, possible tympano-ossicular dysfunction and unclassifiable). Reliability was estimated by means of the kappa (kappa) coefficient on 161 tympanograms from 59 ears for which the interpretation of the three tympanograms agreed. MAIN RESULTS: The interpretation of the three tympanograms agreed for 34 of the 59 ears (0.58) (kappa = 0.52, 95% confidence limits 0.45 and 0.59). There was no significant difference in interobserver reliability between pairs of observers or between symptomatic and asymptomatic ears. CONCLUSIONS: The interobserver reliability of the MicroTymp is moderate. The tympanograms obtained with the instrument should be interpreted in the context of the clinical findings.     

The postauricular fascial flap as an adjunct to Mustardé and Furnas type otoplasty.

Anterior riberation methods of otoplasty have been criticized because of the risk of anterior hematoma that can cause anterior skin necrosis, scarring, and even cartilage destruction caused by infection. As a result, cartilage-sparing otoplasty such as the Mustardé and Furnas types has been increasingly popular. However, postauricular suture extrusion may result, and recurrence rates of up to 25 percent have been recorded. In this study, cartilage-sparing otoplasty is refined by the addition of a postauricular fascial flap to reduce suture extrusion and recurrence rates. Fifty-one patients underwent otoplasty (45 bilateral, six unilateral). This technique involves the elevation of a fascial flap from the postauricular region. A new antihelical fold is then created by Mustardé sutures, and the conchal bowl is rotated by Furnas-type concha-mastoid sutures. The fascial flap is then advanced to cover the sutures with a supplementary vascularized layer to prevent suture extrusion. In addition, the advancement of the flap acts as a postauricular support to prevent recurrence. A natural-looking antihelical fold and helical rim is created by this technique. There were no hematomas. There was recurrence in eight ears (8 percent) in six patients. Two patients requested further surgery. No patients developed suture extrusion or granuloma. This is a simple and intrinsically safe procedure and does not cause irreparable complications such as anterior scarring or skin necrosis. The postauricular fascial flap seems to prevent suture extrusion. It may also help to reduce recurrence rates to acceptable levels.     

内耳免疫反应诱导Fas和FasL表达与凋亡的关系

目的研究内耳免疫反应过程中是否存在细胞凋亡,以及细胞凋亡是否与Fas和FasL信号转导有关.方法选用雌性白色豚鼠16只,随机分为实验组和对照组各8只,以钥孔虫戚血蓝蛋白(keyhole limpet hemocyanin,KLH)全身免疫后,实验组以相同抗原进行内耳免疫,对照组内耳注射等量的磷酸盐缓冲生理盐水(phosphate buffered saline,PBS),在内耳免疫5d后处死动物,取内耳免疫侧耳蜗做石蜡切片.通过脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术(terminal-deoxynucleotidyl transferase mediated nick end labeling,TUNEL)检测内耳凋亡细胞,免疫组化检测内耳Fas和FasL的表达.结果实验组豚鼠内耳Corti器毛细胞,血管纹的缘细胞和螺旋神经节细胞存在TUNEL染色阳性细胞,而对照组动物切片仅在支持细胞、血管纹和螺旋神经节细胞中发现极少数TUNEL染色阳性细胞.免疫组化染色实验组Corti器、螺旋神经节细胞、血管纹和螺旋韧带Fas和FasL蛋白表达阳性,而对照组只有螺旋神经节细胞和血管纹有较弱的Fas蛋白表达,FasL蛋白表达阴性.结论内耳免疫反应可诱导细胞凋亡的发生,Fas-FasL途径是参与此过程重要的信号转导途径之一.     

慢性化脓性中耳炎患者耳道分泌物的病原菌检测及药物敏感性分析

目的分析慢性化脓性中耳炎(CSOM)患者耳道分泌物的病原菌分布及其药敏情况,为临床合理应用抗菌药物提供参考。方法收集浙江省立同德医院100例(116耳)CSOM患者耳道分泌物标本进行常规病原菌分离、鉴定及药敏试验。结果 116耳中有97耳培养出病原菌,检出率为83.6%。共检出病原菌103株,其中革兰阳性菌占53.4%(55/103),革兰阴性菌占41.7%(43/103),真菌占4.9%(5/103)。金黄色葡萄球菌和表皮葡萄球菌对青霉素和磺胺甲唑/甲氧苄啶耐药性较高,对利福平和莫西沙星敏感性较高,对呋喃妥因和万古霉素完全敏感。铜绿假单胞菌和肺炎克雷伯菌对头孢唑啉、氨苄西林、头孢吡肟、头孢曲松、哌拉西林/舒巴坦耐药性均较高,对妥布霉素、氨曲南、哌拉西林/他唑巴坦敏感性较高,对阿米卡星、美罗培南及亚胺培南完全敏感。真菌对氟胞嘧啶、两性霉素B及制霉菌素均敏感,而对酮康唑和氟康唑有一定的耐药性。结论 CSOM患者耳道分泌物中病原菌以金黄色葡萄球菌、表皮葡萄球菌、铜绿假单胞菌及肺炎克雷伯菌为主,这4种病原菌对多数常用抗菌药物有较强的耐药性,治疗时需根据细菌培养及药敏分析结果合理选用抗菌药物。     

The effect of sucrose on the levels of abscisic acid, indoleacetic acid and zeatin/zeatin riboside in wheat ears growing in liquid culture

The influence of a varied sucrose supply on grain size and hormonal contents of detached wheat ears ( Triticwn aestivum L. cv. Schirokko) was investigated throughout grain development. In ears led limited amounts, or no sucrose, grain weights in both proximal and distal grain positions of the ear were reduced. Radioimmunoassay for abscisic acid, indoleacetic acid and zeatin/zeatin riboside showed that the changes in the levels of these hormones in grains and bracts were comparable to intact ears when detached ears were well supplied with sucrose. Under conditions of limited sucrose supply, higher abscisic acid levels in the distal and proximal grains of detached ears were found compared to ears supplied with adequate sucrose. Limiting sucrose supply to the ear did not alter the levels of indoleacetic acid or zeatin/zeatin riboside in either the grains or bracts of detached ears.     

Microtia reconstruction: does the cartilage framework grow?

The use of free rib cartilage ear frameworks in unilateral microtia reconstruction has prompted much discussion about their potential for growth. The senior author has reconstructed ear frameworks in 132 microtia patients, most of whom were under 3 years of age when surgery was initiated. Of this group, 29 were assessed for ear growth through comparison of the lead-plate model of the original normal ear to the normal ear growth and the reconstructed ear framework after a period of at least 2 years. Similarly, 14 reconstructed ears were compared to 14 normal ears at least 2 years after reconstruction. The perimeters of tracings made from the original lead plates and of tracings of normal and reconstructed ears were determined by image analysis techniques. The results demonstrated no significant difference in growth between normal ears and reconstructed ear frameworks after an interval of at least 2.5 years. Therefore, the reconstructed ear is growing at a rate similar to that of the normal ear.     

Proteomic Analysis Revealed Nitrogen-mediated Metabolic, Developmental, and Hormonal Regulation of Maize (Zea mays L.) Ear Growth

Optimal nitrogen (N) supply is critical for achieving high grain yield of maize. It is well established that N deficiency significantly reduces grain yield and N oversupply reduces N use efficiency without significant yield increase. However, the underlying proteomic mechanism remains poorly understood. The present field study showed that N deficiency significantly reduced ear size and dry matter accumulation in the cob and grain, directly resulting in a significant decrease in grain yield. The N content, biomass accumulation, and proteomic variations were further analysed in young ears at the silking stage under different N regimes. N deficiency significantly reduced N content and biomass accumulation in young ears of maize plants. Proteomic analysis identified 47 proteins with significant differential accumulation in young ears under different N treatments. Eighteen proteins also responded to other abiotic and biotic stresses, suggesting that N nutritional imbalance triggered a general stress response. Importantly, 24 proteins are involved in regulation of hormonal metabolism and functions, ear development, and C/N metabolism in young ears, indicating profound impacts of N nutrition on ear growth and grain yield at the proteomic level.     

Effects of variation in ear temperature on growth and yield of spring wheat

Wheat plants were kept in a growth room at 15 ^oC from 7 days after an-thesis until maturity and their ears were warmed to 20 or 25 ^oC for various periods. Continuous warming initially increased the growth rate of the ear and decreased that of the stem, but hastened senescence of the ear and decreased final grain yield by decreasing dry weight per grain. Warming the ears increased the movement of ¹⁴C and nitrogen to them from the leaves and stem during the early stages of grain growth but decreased it later. Warming the ears for only the first 10 or 20 days also hastened ear senescence; grain yield decreased progressively with increase in duration of the warm period. All effects were greater at 25 than at 20 ^oC. The effects of changing ear temperature from 15 to 20 ^oC were independent of the temperature of the rest of the plant. Altering the humidity of the air around the ears by 4–7 mb at constant temperature had no effect on ear growth or senescence. Warming all of the plant except the ears from 15 to 20 ^oC increased ear growth slightly during early grain growth and decreased it later, irrespective of ear temperature: stem dry weight, leaf area and net photosynthetic rate of flag leaves and green stems were decreased and dark respiration rate of stems was increased.