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1.
Summary In breeding tomatoes (Lycopersicum esculentum
Mill.) for resistance to the foot-and stemrot disease, caused by Ascochyta hortorum, the imperfect stage of Didymella lycopersici, the early screening of seedlings for resistance to this disease should greatly reduce labour and expense. Yet inoculation of susceptible seedlings has so far resulted in a number of escapes.The experiments described showed that with a soil temperature of 10–15°C, 100% infection of very young susceptible seedlings could be obtained within 10 days after inoculation. Comparing different methods of inoculation it was found that watering the base of the stem with a concentrated suspension of an 18-day old culture grown at 22°C was quick and reliable. Although wounding did speed up lesion development, as reported by previous workers, initial screening could be done on unwounded seedlings. The observation indicated that the effect of light during the incubation period was more obvious at temperatures above 15°C.These findings were used in the selection of resistant plants from wild species of Lycopersicum for breeding work.
On study leave from: The Cocoa Research Institute, New Tafo, Ghana. 相似文献
On study leave from: The Cocoa Research Institute, New Tafo, Ghana. 相似文献
2.
Summary Several varieties of Cucurbita moschata were found resistant to cucumber mosaic virus (CMV). Inter-specific hybridization between C. pepo and a CMV resistant variety of C. moschata resulted in partial fertile hybrids which set F2 seeds. Cotyledonary inoculation of F2 seedlings with CMV brought various results, depending on seasonal differences and developmental stages at which observations were made. Resistance to CMV generally declined under conditions of low temperature, short days and low light intensity. 相似文献
3.
Summary The resistance to Verticillium wilt was investigated by inoculating the roots of runner plants and young seedlings of strawberry (Fragaria x ananassa
Duch). In the glasshouse tests a satisfactory method was to raise the plants in jiffy pots and to remove the bottom of the pots prior to inoculation. This has the advantage that only slight root damage and no growth stagnation are caused.Both in the glasshouse and field tests inoculation resulted in a distinct infection reflected in reduced plant vigour and lesions on the petioles followed by wilting. In this way reliable differences between varieties could be demonstrated.The varieties grown in the glasshouse did not always exhibit the same degree of susceptibility as observed in practice. For example, Talisman and Redgauntlet were susceptible, while Gorella seemed to be more resistant because clear disease symptoms were not visible; the reduced plant vigour, however, indicated definite susceptibility. Generally the degree of infection and the reduction in growth were found to be significantly correlated.The two field trials carried out with plants the roots of which were infected by immersion in a suspension before planting, produced results which agreed better with practical findings than the glasshouse tests. In these trials Siletz appeared to be the most resistant variety, some American varieties and selections were nearly resistant, Vola and Juspa being not very susceptible. 相似文献
4.
Inheritance of resistance to anthracnose at fruiting and seedling stages was studied in two F2 populations from a cross between Capsicum annuum cv. ‘Bangchang’ and Capsicum chinense‘PBC932’. The first F2 was used to study anthracnose resistance at fruiting stage on mature green and ripe red fruit, and the second F2 was used to study the resistance at both seedling and fruiting stages. Fruit inoculation was performed on detached fruit using a microinjector. Disease severity was assessed on a 0–9 scale at 7 days after inoculation. Seedling inoculation was performed using a drop method on detached leaves of 4‐week‐old seedlings. Disease severity was assessed on a 1–9 scale at 3 days after inoculation. The distribution of the disease scores of green and red fruit, and seedlings in both F2 populations suggested a single gene model for each trait. Three different recessive genes were responsible for the three resistances from this cross. Linkage analysis suggested that the resistances at green and red fruit were linked (recombination frequency 0.25), and that the seedling resistance was not linked to the fruit resistances. 相似文献
5.
Summary While various methods of testing for neck rot resistance were compared, it was found thatBotrytis allii behaves as a wound parasite and that its pathogenicity is rather low. The degree of infection was strongly influenced by the amount of inoculum by the temperature at which the cultures were stored and by storage duration. Besides, infection appeared to be much influenced by pre-treating, the inoculated bulbs, the method of inoculation and finally the environmental conditions after inoculation.Three test methods were compared: inoculation of seedlings, of detached leaves and of bulbs. The bulb test seemed the most suitable because of its reliability and the possibility of carrying out the test at any desired period in autumn or winter. A drawback of the bulb test is that it is rather laborious.The results of the seedling test indicated that seedlings of the cultivated onion (Allium cepa) hardly ever showed any resistance. OtherAllium species proved highly resistant during the seedling stage. In an older stage however, the leaves of most of these species were found to be almost as susceptible as those of onion. The foliage of some ornamental onion species appeared to be very resistant.The test of about 20,000 bulbs of the cultivated onion yielded some strikingly resistant individuals.Samenvatting
Het toetsen van uien (Allium cepa
L.) en andere Allium soorten op resistentie tegen Botrytis allii
Munn.Bij het vergelijken van verschillende methoden voor het toetsen op resistentie tegen koprot werd gevonden datB. allii zich gedraagt als een wondparasiet en dat de pathogeniteit van deze schimmel tamelijk gering is. De mate van infectie werd zeer beïnvloed door de hoeveelheid inoculum, door de temperatuur waarbij de sporen waren bewaard en door de tijdsduur van de bewaring. De infectie bleek ook sterk af te hangen van de voorbehandeling van de geï noculeerde bollen, de methode van inoculeren en tenslotte van de uitwendige omstandigheden na inoculatie.Er werden drie methoden onderling vergeleken: de toetsing van zaailingen, van afgeknipt blad en van bollen. Hiervan leek de bollentoets de geschiktste vanwege zijn betrouwbaarheid en de mogelijkheid de toets op elk gewenst moment in de herfst of de winter uit te voeren. Een nadeel is dat deze methode vrij veel arbeid vergt.De resultaten van de zaailingentoets toonden aan, dat zaailingen van de cultuur-ui nauwelijks enige resistentie bezitten.Als zaailing bleken andereAllium-soorten zeer resistent. In een later stadium bleken de bladeren van de meeste van deze soorten echter bijna even gevoelig te zijn als die van de ui.Enkele sieruiensoorten hadden zeer resistent blad.Het toetsen van ongeveer 20.000 bollen vanAllium cepa leverde enkele opvallend resistente exemplaren op. 相似文献
6.
Summary Six inoculation techniques were compared for the artificial promotion of downy mildew (Peronosclerospora sorghi) in sorghum. These were (1) sprouted seeds incubated between sporulating infected leaves, (2) sprouted seeds depped in conidial suspension, (3) sprouted seeds sprayed with conidial suspension, (4) seedlings at plumule stage inoculated with drops of a conidial suspension, (5) seedlings at plumule stage sprayed with a conidial suspension, and (6) seedling showered with conidia falling from infected leaves. Seedlings at the one-leaf stage sprayed with a conidial suspension (6 × 105 ml-1) showed the highest systemic infection (100%) in the susceptible lines IS 643 and IS 18433. This technique is effective, repeatable, and allows the deposition of a conidial suspension as a fine mist on the entire seedling surface. In the greenhouse, the technique was used to test the downy mildew reaction of genotypes previously reported as resistant (< 5% incidence) in 3–4 years of field screenings. Of the 61 genotypes tested, 21 were free from downy mildew, 14 had less than 5% incidence, and the rest showed variable susceptible reactions. Therefore, the technique can be reliably and effectively used in the greenhouse to detect disease escapes and to indentify resistance. 相似文献
7.
接种AM真菌对烤烟生长、营养及抗旱性的影响 总被引：6，自引：0，他引：6
试验利用漂浮育苗技术,接种丛枝菌根真菌根内球囊霉(Glomus intraradices 193,编号BEG-193)、幼套球囊霉(Glomuse etunicatum,编号BEG-168和BGC-HEB07A)生产菌根烟苗,研究了AM真菌对烤烟生长、营养和抗旱性的影响。结果表明,烟苗生长对水分供应比较敏感,轻度干旱使它们的生物量降低27.24%。在干旱条件下,接种BEG-193和BGC-HEB07A的烟苗生物量显著高于不接种,接种BEG-168无效。接种AM真菌总体上有益于提高烟苗的氮、磷、钾含量和吸收量。此外,干旱使叶片丙二醛含量显著增加了1.71倍(轻度干旱)和5.56倍(重度干旱);而只有在重度干旱条件下叶绿素含量和根系活力才会显著降低,说明干旱容易造成膜脂氧化伤害。接种AM真菌之后,干旱时叶片丙二醛含量低于但叶绿素含量和根系活力高于不接种的烟苗,说明接种AM减轻了干旱对细胞膜的伤害作用,并保持了较强的光合作用和养分吸收能力。接种AM真菌对烟苗生物量、营养状况、丙二醛、叶绿素和根系活力的影响因菌株不同而异,也与干旱程度有关。在生产菌根苗的过程中,选择适宜的菌株是必要的。 相似文献
8.
Summary When screening populations segregating for resistance to Corynebacterium michiganense a rapid and reliable inoculation technique is needed. From the several techniques tested, inoculation of the petiole was found to give better differentiation of resistant and susceptible plants than did inoculation of the root or leaf. When petiole-inoculation was compared with stem-inoculation the latter showed the lowest environmental variation and is suggested for use in genetic studies. Stem-inoculation involved clipping the stems of 4 week old seedlings 1 cm above the cotyledonary leaves with scissors which had been dipped in inoculum.Petiole inoculation and, to a lesser degree, stem inoculation failed to produce uniform infection, resulting in variation in the expression of the disease. The scoring was therefore based on the presence, and not the degree, of wilting and stunting, or the size of the cankers. Plants free of all these symptoms were rated resistant. The coefficient of variation for vascular discoloration on individual plants was calculated to be 50%, which in part may be explained by the histopathology of the host.The virulent isolates cm 21 caused death of seedlings resistant to isolate H. However, cultivars resistant to isolate H in the seedling stage did not decrease in fruit weight as compared to susceptible cultivars when inoculated with isolate cm 21 at anthesis.Michigan Agricultural Experiment Station Journal No. 7424. 相似文献
9.
不同浓度营养液对烤烟漂浮育苗烟苗生长及生理特性的影响 总被引：15，自引：1，他引：14
试验采用漂浮育苗方式对K326包衣种子进行了不同浓度营养液对烤烟烟苗生长及生理特性的影响进行了研究。试验设8个处理（以氮含量计算）0,50,75,100,125,150,175,200mg／L。结果表明,播种后30d和35d,随着营养液浓度的增加,烟苗的株高、叶数、一级侧根、二级侧根、根体积和干物质重依次增加;播种后45d和50d,在100—150mg／L范围内烟苗的各生物学性状表现较好。播种后46d,随营养液浓度的增加,NR活性逐渐下降,除此以外,在0～125mg／L范围内可溶性蛋白质含量和NR活性在整个苗期随营养液浓度的增加逐渐上升,超过125mg／L又呈下降趋势;INV活性在整个苗期都呈先降后增趋势,在150mg／L时活性最弱。 相似文献
10.
为了阐明黑腐病对苗期花椰菜的根系形态和生理的影响,对建立花椰菜抗黑腐病根系育种新途径提供依据,利用黑腐病菌感染花椰菜抗病品种雪峰的叶片后,研究植株根系发生的一系列形态和生理变化。结果表明,接种7天后的植株根长、根干重、地上部干重、根系活力比接种后2天的显著增加。接种处理的植株根长、根干重和地上部干重明显比未接种对照（CK）低,但是接种幼苗的根系活力比未接种对照的根系活力高。接种3天后,接种处理的根系可溶性蛋白质含量一直显著高于未接种对照;接种后0~4天,接种处理的根系超氧化物歧化酶（SOD）活性明显低于未接种对照,但到接种后5~7天,接种处理的根系SOD活性又高于未接种对照;根系多酚氧化酶（PPO）活性和脱落酸（ABA）含量在植株接种后都显著高于未接种对照。但是,黑腐病病原菌没有提高根系过氧化物酶（POD）活性。以上结果说明,黑腐病菌引起了花椰菜幼苗根部一系列形态变化,并通过诱导植株根系中防御酶活性和调控内源激素等抵御病原菌的进一步侵染。 相似文献
11.
Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts 总被引：7，自引：0，他引：7
Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed. 相似文献
12.
Expression of resistance to downy mildew at cotyledon and adult plant stages in Brassica oleracea L.
This research compared the expression of resistance to downy mildew at cotyledon and adult plant stages in seven Brassica oleracea genotypes against two P. parasitica isolates of different virulence. Seven day old seedlings were dual inoculated under controlled environment by depositing
two 10 μl droplets of a spore suspension of a different isolate on each cotyledon and the interaction phenotype (IP) evaluated
7 days later using a 0–5 scale of increasing susceptibility. The seedlings were transplanted to 16 cm pots and grown in the
greenhouse for 110 days (15 to 28 leaves). Adult plants were tested using a single leaf inoculation method that allowed the
same plant to be simultaneously inoculated with the two P. parasitica isolates. Leaves were scored 10 days after inoculation using a 0–5 scale of increasing susceptibility. The inoculation of
the same plant with the two isolates produced different combinations of cotyledon (CT) and adult-plant (AP) interaction-phenotype
according to the genotype. CrGC 3.1 was susceptible at CT and AP stages, ‘Algarvia’ resistant at CT and AP stages, and broccoli
‘A’ susceptible at CT and resistant at AP stage against the two isolates. ‘Murciana’ and broccoli ‘B’ were differential at
CT and AP stages. Savoy and Shetland cabbages were differential at CT stage and resistant to both isolates as adult plants.
Cotyledon resistance could not be used to predict adult-plant resistance since the two types of resistance were very poorly
correlated. Resistance can be race specific either at cotyledon or at adult-plant stage.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Shoot and root growth and plant dry weight were determined for twenty four accessions of pearl millet, Pennisetum americanum (L.) Leeke, after two weeks growth in saline solution culture at EC 20 dS m-1. The EC was achieved using NaCl + CaCl2 1:1 by weight in solution culture. Although salinity markedly inhibited growth of all accessions, three, 93613, KAT/PM-2 Kitui, and Kitui local produced significantly greater dry matter, and they and 93612 had longer shoots than the other accessions. Accessions WCA 78 and Bulk 7704 were highly sensitive to salinity in all 3 characters measured. There was considerable variation between the 24 accessions, suggesting that selection for increased tolerance to salinity in pearl millet should be possible. This was examined using normal seed of the cultivar Al/3. A first cycle of selection screened 16,000 seeds after 15 days growth in nutrient solution at EC 26 dS m-1. 106 individuals were selected to form the S1 selection line. Selected seedlings were grown to maturity and polycrossed. In a second cycle of selection, 30,000 S1 polycross progeny were screened as previously, but at EC 30 dS m-1. A selection intensity of 0.08% was achieved. The selected plants were again grown to maturity and again polycrossed. Efficiency of the selection procedure was assessed from comparison in sand culture of the performance of the selected line with the unselected Al/3 line and Kitui local which from the previous assessment of the 24 accessions was rated as relatively salinity tolerant. The selection line was superior to the other two lines at four salinity levels. The results of this study suggest that further improvement in salinity tolerance in pearl millet may be expected from further selection and breeding, using the methods described here. 相似文献
14.
Summary Roots, leaf petioles, shoot tips and immature fruits of female date palm formed the source material for in vitro cultures. Isolated embryos excised from mature seeds were also cultured. Of all the tissues, some of the leaf petioles and fruit mesocarp gave rise to calluses in the media of Staritsky (1970) and Eeuwens (1976). Isolated embryos germinated to produce seedlings in MS (Murashige & Skoog, 1962) medium. Calluses were established from seedling sections but the growth conditions propitious for explants of seedlings were not suitable for female date palm tissues. The main problem in establishing long term tissue cultures has been the browning of the tissues and media. This problem was, at least partially, overcome by adding activated charcoal to the liquid media and cysteine to the solid madia. So far, shoot regeneration in the calluses could not be induced. 相似文献
15.
Summary A series of experiments was performed in order to evaluate the significance of seed germination and seedling growth in osmotic media as screening methods for drought tolerance.Ten spring wheat (Triticum aestivum L. em Thell.) and one durum wheat (Triticum durum
Desf.) were tested under controlled environments, using polyethylene glycol-6000 (PEG) solutions as the moisture stress inducing media.Tolerance in the rate of endosperm utilization, under stress, prior to the onset of germination varied among cultivars.Germination rate or injury to germination at various concentrations of PEG differed significantly among cultivars. Cultivar rating with respect to injury to germination changed with stress levels. Injury to germination did not correlate with endosperm utilization rate in PEG or in water.Germinating seedlings were tolerant to extreme desiccation up to the stage of emergence of the first leaf from the coleoptile.Growth of photosynthesizing seedlings was monitored as they were carried through an increasing concentration gradient of PEG solutions, ranging from –5.9 to –11.3 bars of water potential. Cultivars significantly differed in seedling growth tolerance to increasing levels of water stress. Seedling growth tolerance across cultivars was not correlated with their germination responses under srress.It is concluded that tolerance to water stress in growing seedlings can be screened for by using PEG-containing nutrient solutions. It can not be predicted from germination tests in osmotica.Work was done under a US-Israel Binational Science Foundation (BSF) Grant no. 1654/78.Contribution from Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No. 192-E, 1979 series. 相似文献
16.
Yeun-Kyung Chang Leslie A. Blischak Richard E. Veilleux Muhammad J. Iqbal 《Euphytica》2010,171(2):251-261
Gametophytic selection has potential to increase the efficiency of breeding for temperature tolerance. Here, we describe orchid
seedlings after application of low and high temperatures during gametophytic development. In addition to phenotypic traits,
amplified fragment length polymorphism (AFLP) markers were used to determine the genetic variability in seedlings. Two hybrid
Phalaenopsis were cross-pollinated and exposed to 30°C day/25°C night for 3 days for a warm pollination or 15°C day/10°C night for 7 days
as a cold pollination treatment. The plants were returned to the greenhouse after pollination and green capsules were collected
after 150 days. Protocorms obtained from these treatments were evaluated 72 days after initial plating for germination and
size on a thermogradient table ranging from 10 to 30°C. Seedlings were then evaluated 1 year after initial plating. The mean
number of roots per seedling (4.2) was greater for plantlets that derived from the cold pollination treatment compared to
those from warm pollination (3.6). Weight of the seedlings, number of roots and the average root length were significantly
affected by the interaction between pollination treatment and germination temperature. The weight, number of leaves, and average
root length were significantly affected by the interaction between pollination treatment and incubator/growth chamber. The
results indicated that seedlings derived from warm pollination were more vigorous under warm growing conditions and those
derived from cold pollination were more vigorous under cold growing conditions. Genetic variation among 16 F1 seedlings randomly selected from various temperature treatments was analyzed. A dendrogram based on 651 loci resulted in
three major groups and one subgroup. The groups and subgroup revealed common selection pressure during the gametophytic stage.
The AFLP data support genetic differentiation of Phalaenopsis hybrids pollinated under different temperatures. 相似文献
17.
机插稻超秧龄秧苗的生长特点研究 总被引：23，自引：2，他引：23
水稻机插移栽中秧苗不能及时机插而生长过度, 形成超秧龄秧苗。本试验以扬粳9538为供试品种, 在不同床土培肥条件下, 观测了超秧龄秧苗的生长特征。在超秧龄初期阶段(至播种后28 d), 秧苗地上部仍维持一定的生长, 秧苗干重和单位苗高干重尚有一定增加, 尚能维持糖氮代谢。但秧苗叶色(SPAD值)迅速下降, 地下部生长停滞, 根长、根数停止增加, 根系活力迅速下降, 根冠比明显降低。在严重超秧龄阶段(至播种后36 d), 苗高依然快速增加, 单位苗高干重大幅下降, 秧苗叶色维持在较低水平。根系活力低, 根系生长处于最低水平。超秧龄生长过程中秧苗糖代谢反应敏感, 氮代谢相对稳定, 糖氮比在严重超秧龄时大幅下降。床土肥力显著影响超秧龄秧苗生长, 高培肥水平下的秧苗茎基粗没有显著变化, 但苗高迅速增加, 单位苗高干重大幅降低, 地下部生长较低培肥处理更弱, 根数和根长较低, 根系活力下降迅速, 根冠比与低培肥处理相比大幅减小。床土培肥水平对秧苗的碳氮代谢影响显著, 高培肥处理的超龄秧苗营养状态更为劣化。以上结果表明, 超秧龄阶段特别是在严重超秧龄阶段的秧苗生长, 很大程度上取决于育秧阶段(适栽期)的育秧条件和生长状况, 低培肥处理的秧苗在超秧龄生长中糖氮比能维持相对较高的水平, 从而维持秧苗相对较好的营养状态。 相似文献
18.
A simple method for screening commercial varieties of potato and other wild and cultivated tuber-bearing Solanums for resistance to root knot nematode Meloidogyne incognita (Kofoid and White) Chitwood, has been described. Leaflets taken from plants which were 6 to 8 weeks old are treated with 5 ppm IBA for 24 hours. Treated leaflets, when kept in water, rooted in 12 to 15 days. Use of paper cups, each containing 50 gm of autoclaved soil, was found to be adequate for free development of the roots from the petiole region of the leaflets. Inoculating the soil in the cups with 20 larvae and incubating them at 25°C for 10 days was found to create good conditions for infection of rootlets and subsequent gall formation by the nematodes. The degree of gall formation on the roots was recorded as the grade of susceptibility or resistance of the plant material under test. 相似文献
19.
氮素与土壤类型对水稻秧苗素质及养分吸收的影响 总被引：1，自引：0，他引：1
为探明2种类型土壤中氮肥用量对水稻秧苗素质及养分吸收特性的影响,试验以中晚熟品种辽粳401为试验材料,选用黏质土和砂质土2种土壤类型,采用随机区组方法研究了4个氮肥处理对水稻秧苗素质及养分吸收的影响。结果表明：黏质土为基质育秧干物质积累量明显大于砂质土培育的秧苗,更有利于秧苗地上部与根系的生长、干物质量的积累及对养分的吸收。播后20~30d期间,黏质土培育秧苗的秧苗素质、根系形态、干物质量呈上升趋势,砂质土培育秧苗生长规律与黏质土处理基本一致,25d前秧苗生长缓慢,而在25~30d期间,秧苗迅速生长,干物质积累量明显不足。施氮量在4g/盘条件下,秧苗素质、根系形态与干物质量最佳,黏质土、砂质土培育秧苗总吸氮量最大分别为4.24、4.03g/盘,故施氮量4g/盘可以满足秧苗对氮素的需求,同时,也可以提高氮素的利用效率,减少氮肥损失。 相似文献
20.
探讨低剂量电子射线对水稻生长的影响,并解析其相关生理机制。用0~50 Gy范围内的5 个剂量辐照‘绥粳4号’水稻种子,以土壤和营养液2种方式培养幼苗,统计出苗率,并在分蘖期对相关农艺性状、部分生理指标进行检测分析。结果表明：较低剂量辐照(＜10 Gy)对水稻出苗率无明显不良影响,较高剂量（30 Gy和50 Gy）有明显的抑制作用。土壤培养时的半致死剂量约为50 Gy;6 Gy辐照对水稻株高和丙二醛含量具有促进作用;6~30 Gy辐照对土壤培养水稻幼苗的叶绿素、可溶性糖、可溶性蛋白含量具有促进作用。不同辐照剂量间差异呈极显著。2 种培养方式对相关生理指标的影响存在差异,营养液培养时植株生长良好,部分缓解了电子射线对水稻生长及相关生理性状的影响。 相似文献