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1.
Andrea Minuto Giovanni Minuto Quirico Migheli Massimo Mocioni M.Lodovica Gullino 《Crop Protection》1997,16(8):765-769
The ability of antagonistic Fusarium spp. to control Fusarium wilt of basil caused by F. oxysporum f. sp. basilici was tested under glasshouse conditions from 1994 to 1996. Fusarium oxysporum antagonistic strain 251/2, a protoplast fusion-derived hybrid coded FI-11 and F. moniliforme strains TF4 and TF4 RB were able to decrease (P = 0.05) the incidence of Fusarium wilt significantly. Biocontrol was consistent, especially when the antagonists were applied by mixing a talc preparation of propagules in the substrate (105 CFU/ml of substrate) 1–2 weeks before sowing or at sowing. Seed coating with the biocontrol strains (108 CFU/g of seed) did not generally provide sufficient disease containment, whereas the combination of substrate treatment and seed coating did not improve wilt control in comparison with substrate treatment alone. Two commercial formulations, based on antagonistic F. oxysporum strains and one containing the antagonistic strain K61 of Streptomyces griseoviridis, were generally not sufficiently effective at the tested dosages. 相似文献
2.
Field experiments and bioassay tests were carried out to evaluate the relative response of the crops, tossa jute (Corchorus olitorius L.) and okra [Abelmoschus esculentus (L.) Moench], and their associated weeds to pre-emergence application of pendimethalin at 0.33, 0.66, 0.99, 1.32 kg ai ha−1 and a pendimethalin+atrazine tank mixture at 1.32+2.05 kg ai ha−1. Bioassay tests were carried out using herbicide solutions of corresponding concentrations and herbicide-treated soil. Field application of pendimethalin at 0.66 kg ai ha−1 and the herbicide mixture in both crops effectively controlled most seedling weeds including Rottboellia cochinchinensis. Euphorbia heterophylla and Calopogonium mucunoides, which persisted from 2 weeks after treatment (WAT) were not controlled. Herbicide application during crop establishment markedly inhibited the growth of both seedling weeds and crops. The mixture caused the highest weed and crop injury. Pendimethalin at 0.33 kg ai ha−1 had minimal effect on these crops. Weed growth, weed tolerance of herbicide treatment and crop seedling injury were higher in tossa jute than that in okra, under the conditions of this study. The use of low pendimethalin doses in an integrated weed management system will ensure effective control of seedling weeds, and prevent crop injury and residue accumulation in edible plant produce. 相似文献
3.
Concentrations in soil and efficacy of 1,3-dichloropropene (1,3-D)+chloropicrin and methyl isothiocyanate (MITC) against the survival of Phytophthora capcisi, Rhizoctonia solani and yellow nutsedge (Cyperus esculentus L.) were studied in plastic-mulched Southern Georgia sandy soil beds. Beds were treated with InLine (60.8% 1,3-D+33.3% chloropicrin) at 93.5, 187, and 280.5 l ha−1 and Vapam (42% metam sodium) 233.8, 467.5 and 701.3 l ha−1. 1,3-D+chloropicrin and MITC concentrations in soil were monitored after drip application for 7 d and 240 h, respectively, from pre-selected sites in beds. 1,3-D+chloropicrin and MITC concentrations decreased with time and distance from the emitter. Survival of P. capsici, R. solani and yellow nutsedge in treated beds was higher with distance from the emitter. These methyl bromide alternatives did not diffuse laterally at effective concentrations beyond the point of application. Improved application techniques are required to improve the lateral distribution of these alternatives. 相似文献
4.
Results are reported from on-farm surveys of N2 fixation in Nepal, conducted between 1994 and 1999, involving the summer legumes soybean, mashbean and groundnut, and the winter legumes lentil and chickpea, at various locations in the Hill and Terai regions of Nepal. Additional less-detailed data were also collected for pigeonpea, grasspea and fababean. There were a total of 107 crops in the major and minor surveys. Estimates of the proportion of legume nitrogen (N) derived from N2 fixation (Pfix) were determined using the natural 15N abundance method. Mean estimates of Pfix for the various species were 62% (soybean), 47% (mashbean), 57% (groundnut), 78% (lentil), 79% (chickpea), 75% (pigeonpea), 87% (grasspea) and 85% (fababean). Estimates of total N fixed (including roots) were 59 kg N ha−1 (soybean), 28 kg N ha−1 (mashbean), 153 kg N ha−1 (groundnut), 72 kg N ha−1 (lentil), 84 kg N ha−1 (chickpea), 412 N ha−1 (pigeonpea) and 80 N ha−1 (grasspea and fababean). The on-farm measurements of N2 fixation were generally similar to those of experimental crops in the same areas of the country. Correlation matrices of soil fertility parameters, shoot dry matter and N, and N2 fixation revealed that the total amounts of N fixed were influenced primarily by crop growth. Based on the above figures, it was estimated that approximately 30,000 t N were fixed annually in Nepal by legumes, valued at US$ 15 million. 相似文献
5.
Subsoil constraints are major limiting factors in crop production in many soils of southern Australia. A field study examined effects of deep incorporation of organic and inorganic amendments in 30–40 cm on soil properties, plant growth and grain yield of wheat (Triticum aestivum var. Ambrook) on a Sodosol with dense sodic subsoil with or without lucerne history in a high rainfall region (long-term average annual rainfall 576 mm) of Victoria. Amendments were applied at a rate of 10–20 t ha−1. Deep ripping alone and deep ripping with gypsum did not significantly affect grain yields. In comparison, application of organic materials doubled biomass production and increased grain yield by 1.7 times. Organic amendment-treated plots produced 60% more grains per area than the untreated control. The crop extracted over 50 mm extra water from below 40 cm soil in organic amendment-treated plots than the untreated control. Nitrogen uptake was almost doubled (403 kg ha−1) in the organic amendment-treated plots than the untreated control (165 kg ha−1). The improved yield with amendments was related to an increase in plant available water in the hostile subsoil, and prolonged greenness of leaves and supply of nitrogen and other nutrients. 相似文献
6.
Field experiments were conducted during two cropping seasons at two sites in Botswana to determine the efficacy of combining glyphosate and tillage in controlling C. dactylon. Treatments consisted of no-tillage, single and double ploughing during winter and spring plus the application of glyphosate at 0, 1.08, and 2.16 kg ha−1 3–4 weeks after the last ploughing. Visual assessment indicated higher levels of grass control from combining glyphosate and tillage than when these elements were applied separately. However, biomass data indicated that either double ploughing or glyphosate application controlled C. dactylon. A single ploughing followed by glyphosate at 2.16 kg ha−1 after a regrowth of C. dactylon may provide an effective and affordable control method to small-scale farmers. 相似文献
7.
Jrgen E. Olesen Elly M. Hansen Margrethe Askegaard Ilse A. Rasmussen 《Field Crops Research》2007,100(2-3):168-178
The effect of nitrogen (N) supply and weeds on grain yield of spring barley was investigated from 1997 to 2004 in an organic farming crop rotation experiment in Denmark on three different soil types varying from coarse sand to sandy loam. Two experimental factors were included in the experiment in a factorial design: (1) catch crop (with and without), and (2) manure (with and without). The crop rotation included grass-clover as a green manure crop. Animal manure was applied as slurry in rates corresponding to 40% of the N demand of the cereal crops.
Application of 50 kg NH4-N ha−1 in manure (slurry) increased average barley grain DM yield by 1.0–1.3 Mg DM ha−1, whereas the use of catch crops (primarily perennial ryegrass) increased grain DM yield by 0.2–0.4 Mg DM ha−1 with the smallest effect on the loamy sand and sandy loam soils and the greatest effect on the coarse sandy soil. Model estimations showed that the average yield reduction from weeds varied from 0.2 to 0.4 Mg DM ha−1 depending on weed species and density. The yield effects of N supply were more predictable and less variable than the effects of weed infestation. The infestation level of leaf diseases was low and not a significant source of yield variation.
The apparent recovery efficiency of N in grains (N use efficiency, NUE) from NH4-N in applied manure varied from 29 to 38%. The NUE of above-ground N in catch crops sampled in November prior to the spring barley varied from 16 to 52% with the largest value on the coarse sandy soil and the smallest value on the sandy loam soil. A comparison of grain yield levels obtained at the different locations with changes in soil organic matter indicated a NUE of 21–26% for soil N mineralisation, which is smaller than that for the mineral N applied in manure. However, this estimate is uncertain and further studies are needed to quantify differences in NUE from various sources of N.
The proportion of perennial weeds in total biomass increased during the experiment, particularly in treatments without manure application. The results show that manure application is a key factor in maintaining good crop yields in arable organic farming on sandy soils, and in securing crops that are sufficiently competitive against perennial weeds. 相似文献
8.
Nitrogen flows and balances as affected by water and nutrient management in a sorghum cropping system of semiarid Burkina Faso 总被引：3，自引：0，他引：3
Robert Zougmor Abdoulaye Mando Leo Stroosnijder Serge Guillobez 《Field Crops Research》2004,90(2-3):235-244
Efficient use of external inputs and water conservation are a prerequisite of sustainable agricultural productivity in semiarid West Africa. A field experiment was carried out during 3 years (2000–2002) at Saria in semiarid Burkina Faso (800 mm of annual rainfall, PET of 2000 mm per year) to assess the effects of stone rows or grass strips of Andropogon gayanus Kunth cv. Bisquamulatus (Hochst. Hack.) as soil and water conservation (SWC) measures, the sole application of an organic (compost-N) or mineral (urea-N) nitrogen and the combined use of SWC and compost-N or urea-N on N flows and balances. The trial was conducted on a Ferric Lixisol with 1.5% slope and comprised nine treatments in two replications. The SWC measures were put along contours lines. During the three consecutive years, all treatments induced negative annual N balances (−75 to −24 kg N ha−1). The main factors explaining these negative balances were N exports by sorghum biomass and soil erosion-induced N losses. Large amounts of N (7 kg N ha−1 per year in 2000 and 44 kg N ha−1 per year in 2002) were lost in the control treatment through runoff and eroded sediments, which corresponds respectively to about 10 and 43% of the total outflow of N. Sole stone rows and grass strips reduced erosion N losses to 8 and 12%, respectively, of the total annual loss. The combined application of SWC measures and nutrients inputs reduced erosion N losses to only 2–7% of the annual N loss. The application of urea-N or compost-N led to the lowest soil N mining over the 3 years, whereas the highest N mining was observed in plots without added N. We conclude that N mining in poor fertile soils of West Africa can be mitigated through an integration of local water and nutrient management practices. 相似文献
9.
为探究韭菜根系分泌物对苦瓜枯萎病菌的化感作用,本研究以‘山东雪韭6号’韭菜和苦瓜枯萎病菌为试验材料,水培法收集韭菜根系分泌物,采用菌丝生长速率和孢子萌发法研究韭菜根系分泌物对苦瓜枯萎病菌的化感作用;利用气相色谱-质谱联用技术（GC-MS）鉴定根系分泌物组成成分,筛选可能的主效化感物质,进一步通过体外抑菌试验验证其化感作用,明确主效化感物质。结果表明,随着韭菜根系分泌物浓度的升高,苦瓜枯萎病菌的菌落直径和孢子萌发数均呈先降后升的趋势,当分泌物浓度为3.22 mg/mL时,抑制作用最大,满足化感作用低浓度促进、高浓度抑制的特性。通过GC-MS鉴定出韭菜根系分泌物中的主要成分为酚类、酯类、烷烃类、醇类、烯类、芳香类,可能的化感物质为邻苯二甲酸二丁酯、2,4-二叔丁基苯酚、2,2°-亚甲基双-(4-甲基-6-叔丁基苯酚)。通过体外抑菌试验证实这3种物质对苦瓜枯萎病菌菌丝生长和孢子萌发都有不同程度的化感抑制作用,且抑菌效果为2,4-二叔丁基苯酚>邻苯二甲酸二丁酯>2,2°-亚甲基双-(4-甲基-6-叔丁基苯酚),明确其为化感物质。由此可知,韭菜根系分泌的主效化感物质对苦瓜枯萎病菌有显著的化感抑制作用,这为苦瓜间套轮作韭菜防控苦瓜枯萎病和研制植物源抑菌剂提供了理论依据和技术支撑。 相似文献
10.
《Field Crops Research》2004,90(2-3):203-212
Previous research indicated that prolific (multi-ear) maize (Zea mays L.) hybrids might perform better than nonprolific (single-ear) hybrids under lower-yielding environments. Field experiments were conducted during 1996–1999 to evaluate the agronomic responses of 10 maize hybrids differing in ear prolificacy under reduced-input and high-input cropping systems. Hybrids were of similar maturity (FAO 400) and divided into two prolificacy groups (prolific versus nonprolific), each consisting of five hybrids. The reduced-input system consisted of plowing at 20–22 cm; fertilization at 105, 104, and 104 kg ha−1 N, P2O5, and K2O; 37–38 000 plants ha−1; and low input of herbicide. The high-input system involved plowing at 30–32 cm; fertilization at 213, 130, and 130 kg ha−1 N, P2O5, and K2O; 60–65 000 plants ha−1; and high input of herbicides. Grain yields significantly decreased under reduced-input compared to high-input cropping system by an average of 26.1%. Significant cropping system×prolificacy group interactions were found for most yield components but not for grain yields. This indicated that both prolificacy groups exhibited a similar yield decrease under the reduced-input system even though prolific hybrids had 1.33 ears per plant compared to only 1.01 ears per plant of nonprolific types. All prolific hybrids responded similarly to various cropping input levels principally by means of changes in kernels per plant, whereas some nonprolific hybrids had greater response through 1000-kernel weight then kernels per plant. Prolific hybrids tended to achieve higher grain yields which averaged 10 414 kg ha−1 compared to 9383 kg ha−1 for nonprolific types partly due to less barren plants per hectare and primarily because of a higher grain weight per plant. Larger grain weights per plant of prolific hybrids were primary due to more kernels per plant in the reduced-input system, and a combined effect of more kernels and heavier 1000-kernel weight per plant in the high-input system. Improved kernel number per plant for prolific hybrids was associated with kernels from secondary ears. Although prolific hybrids outyielded nonprolific types, our findings failed to indicate that the prolificacy trait per se had any important effect on hybrid performance when grown under reduced-input compared to high-input cropping system. 相似文献
11.
Acetic acid was an effective postharvest fumigant to destroy fungal spores on peaches, nectarines, apricots, and cherries. Decay by Monilinia fructicola and Rhizopus stolonifer on Harbrite peaches was prevented by as little as 1.4 or 2.7 mg l−1 acetic acid, respectively. Harbrite peaches fumigated with 2.7 mg l−1 acetic acid were slightly injured, the phytotoxicity indicated by light brown streaks. Higher concentrations of acetic acid increased injury; the streaks darkened and became much more pronounced. Glohaven peaches treated in the orchard with captan at 5% bloom, full bloom, ripening fruit, and 2 days before harvest then fumigated with 2.7 mg l−1 acetic acid after harvest had significantly less postharvest brown rot (12.5%) than fruit treated with captan alone (25.0%). Decay of Lambert cherries, primarily due to Alternaria spp., was reduced from 38.9 to 10.0% by fumigation with 2.7 mg l−1 acetic acid. Unfortunately, small pits developed in the fruit surface during storage at 1 °C. Brown rot (M. fructicola) of Tilton apricots was reduced from 100 to 25% by fumigation with 2.0 mg l−1 acetic acid without signs of severe phytotoxicity. 相似文献
12.
由尖孢镰刀菌引起的枯萎病是制约作物生产的世界性重要土传维管束病害,危害的作物种类多,损失严重,生产中尚无经济有效的防治方法。抑病型土壤是指对土传作物病害有抑制作用的一类土壤,具有有益微生物种群结构稳定、对土传病害防效持久等特点,因此国内外专家进行了许多卓有成效的研究。本文对尖孢镰刀菌枯萎病相关抑病型土壤的形成因素、作用机制等方面的研究进展进行综述,并对今后尖孢镰刀菌枯萎病抑病型土壤研究的重点方向及应用前景进行了分析和展望,以其为下一步深入研究尖孢镰刀菌枯萎病抑病型土壤的微生物种群结构、有益微生物种类构成、抑病型土壤的构建方法及复合微生物菌肥研制提供新的参考。 相似文献
13.
Smy1是一种参与调控真菌生长的驱动蛋白。本研究克隆了香蕉枯萎病菌4号生理小种（Foc 4）驱动蛋白基因smy1,并采用同源重组技术获得smy1敲除的野生型Foc 4的smy1敲除突变体。通过测定突变体菌丝形态、生长速度、产生孢子量、对香蕉苗的致病力及对氰烯菌酯的敏感性,用于研究smy1在香蕉枯萎病菌的生长发育及对氰烯菌酯抗药性中的作用。结果表明,与野生型Foc 4相比,smy1敲除突变体生长缓慢、菌丝畸形、产孢量增加,对巴西蕉苗的致病力减弱,但对氰烯菌酯的抗性水平变化不大。由此推断smy1基因可能在Foc 4的生长发育、产孢以及致病力等方面具有重要作用。 相似文献
14.
本研究克隆鉴定了香蕉枯萎病菌4号生理小种（Foc4）的细胞周期蛋白C1（Fusarium Cyclin C1,FCC1）基因FocFCC1,采用Split-marker同源重组技术获得基因敲除突变体ΔFocFCC1,通过比较突变体和野生菌株在生长速度、产孢量和致病力等方面的差异,探索了FocFCC1基因缺失对香蕉枯萎病菌生物学功能的影响,并评估了FocFCC1作为枯萎菌内源报告基因的可行性。结果表明：与Foc4野生型菌株相比,ΔFocFCC1菌丝生长缓慢、菌丝畸形及产孢量减少,对巴西蕉苗的致病力明显减弱,推测FocFCC1基因在Foc4的生长发育、产孢及致病力等方面具有重要作用。以FocFCC1为靶标基因,评估了两种基因敲除重组方法介导的基因敲除效率,利用红色表型作为判断依据,挑取再生板上有红色表型的转化子进行PCR检测,Split-marker重组方法获得阳性转化子比例为91.7%,而多片段装配融合方法获得阳性转化子的比例为64%。ΔFocFCC1出现典型红色菌落,红色表型与PCR检测的FocFCC1阳性敲除转化子一一对应,FocFCC1基因敲除后红色表型肉眼容易分辨,可作为香蕉枯萎病菌内源报告基因探索新的遗传操作技术在该菌上应用的可行性。 相似文献
15.
Strains of B. lactucae insensitive to 0.01 g a.i. l−1 metalaxyl have been detected in all the lettuce-growing districts of South Australia. Despite this, applications of a formulated mixture of 0.25 g a.i. l−1 metalaxyl and 2 g a.i. l−1 mancozeb every 7–10 days controlled downy mildew in field experiments, where similar applications of either metalaxyl or mancozeb alone were ineffective. Protectant schedules of either 0.3 g a.i. l−1 dimethomorph or 2–2.4 g a.i. l−1 phosphonic acid also controlled downy mildew, but were less effective than the metalaxyl/mancozeb formulation. Mixtures of either dimethomorph or phosphonic acid with mancozeb enabled the time between the sprays to be increased to 14 days without significantly reducing control. Fungicide applications increased marketable yield by 60% compared with that of the unsprayed plants. Drenching seedlings with 4 g a.i. l−1 phosphonic acid controlled downy mildew for at least 14 days and should prevent the spread of the disease from plant production areas. 相似文献
16.
香蕉枯萎病是全世界香蕉产业共同面临的毁灭性病害,但目前生产上仍缺乏适宜的抗病品种和有效的治疗措施。因此,借助快速准确的枯萎病菌检测技术及时明确病原菌以控制该病的传播和蔓延显得尤为重要。本文回顾了近年来国内外香蕉枯萎病菌分子检测技术的发展历程,归纳和总结了DNA指纹图谱、普通PCR、多重PCR、荧光定量PCR及等温扩增技术在该病菌检测中的研究进展,分析了不同检测技术的优缺点,并指出可能存在的问题和研究发展方向,为该病的分子检测技术优化和防控策略制定提供参考。 相似文献
17.
S. Foti G. Mauromicale S. A. Raccuia B. Fallico F. Fanella E. Maccarone 《Industrial Crops and Products》1999,10(3):3167-228
Globe artichoke (Cynara scolymus L.) and cultivated cardoon (C. cardunculus L. var. altilis DC.) are horticulturally important crop plants. These species have potential as biomass and oilseed crops. We field tested, for 3 years, two artichoke and two cardoon cultivars and one wild cardoon (C. cardunculus L. var. sylvestris Lam.) population on the Sicilian plain of Catania (37°27′ N, 15°04′ E, 10 m a.s.l.). On a 3-year average, the dry aboveground biomass resulted about 31 t ha−1 in both cultivated cardoons, 18.8 t ha−1 in wild cardoon, 13.7 t ha−1 in globe artichoke ‘3/10 V.S.’ and 9.9 t ha−1 in globe artichoke ‘374’ F1. The caloric values of aboveground biomass (except for seeds), which was not significantly different among genotypes, ranged between 16 005 and 17 028 KJ kg−1 of dry matter. The cultivated cardoon ‘Gigante di Lucca’ had the greatest grain yield (on 3-year average, 2.6 t ha−1), whereas the two globe artichokes had the lowest yield (on 3-year average, 0.5 t ha−1). Regardless of genotypes and years, the grains contain 20.1% crude protein, 24.4% oil, 18.5% crude fiber and 4.1% ash (dry weight basis). The grains of globe artichokes showed the highest crude protein content (21.6%), whereas those of cardoons the highest oil content (25.2%). 相似文献
18.
S. K. Patil U. Singh V. P. Singh V. N. Mishra R. O. Das J. Henao 《Field Crops Research》2001,70(3):185-199
Rice (Oryza sativa L.) followed by chickpea (Cicer arietinum L.) or a fallow is one of the predominant cropping systems in the rainfed lowlands of India. Crop rotation experiments over 3 years (1996–1998) to quantify N supply and demand under rainfed lowland rice–chickpea and rice–fallow cropping systems on a loam Alfisol and a clay Vertisol in Raipur, India were conducted under direct-seeded rice culture. The rice growth, yield, development and N accumulation were affected most by N rates (0, 40, 80, 120 kg ha−1) followed by cropping system (rice–chickpea, rice–fallow) and soil types (Alfisol, Vertisol). The incorporation of chickpea in the cropping system helped in accumulating a greater amount of soil N than fallow. The rice yield, dry matter and N accumulated were significantly higher in rice–chickpea than rice–fallow systems on both soils and in all years. The lowest rice yields were recorded in 1997 due to unfavorable rainfall distribution. The total rainfall was the highest in this season, but most of it occurred during a short period at an early growth stage. The post-heading rains were lowest in this season and resulted in the lower rice yield as compared with that of 1996 and 1998. This indicates the significance of rainfall distribution in controlling yield in a rainfed environment. The rice yields were lower on Vertisol than Alfisol during periods of drought. The performance of chickpea was also better in Alfisol as compared with that in the Vertisol due to its better soil physical attributes. The residual effect of N applied to the preceding rice crop was non-significant on all yield, growth and N accumulation parameters of chickpea. The N balance computed from the top 70 cm soil layers indicated less N loss in the rice–chickpea system as compared with that in rice–fallow. The recovery efficiency at the highest N rate (120 kg N ha−1) was higher for the rice–chickpea (57–61%) than that of rice–fallow (49–53%) system. The improved N balance for rice–chickpea system from third year onwards was due to switch to dry seeding and improved soil N status. The inclusion of legume and the effective capture of biologically fixed N and soil N through direct-seeded rice system in rainfed lowlands may help in improving the rice yield of resource poor farmers. 相似文献
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20.
To develop strategies to manage Fusarium wilt of Hiemalis begonias (Begonia×Hiemalis), caused by Fusarium foetens, studies were conducted to understand how the disease might be spread in the greenhouse. Inoculum density studies showed that as few as 100 conidial ml−1 were sufficient to cause significant disease indicating that shared irrigation systems need strict sanitation along with bench tops, pots, and trays. The role of fungus gnats (Bradysia spp.) in vectoring F. foetens within a greenhouse was studied using nylon tent cages with diseased and healthy Hiemalis begonias. Fungus gnats were released into half of the cages. In cages where fungus gnats were present only healthy plants became diseased, indicating the effectiveness of fungus gnats in spreading Fusarium wilt. The pathogen was also isolated from adult fungus gnats. In vitro studies showed that two commercially available H2O2-based compounds, ZeroTol® (2.0% peroxyacetic acid and 27.0% hydrogen peroxide), and SaniDate® (12.0% peroxyacetic acid and 18.5% hydrogen peroxide), were effective in causing 100% spore mortality at rates that would allow their use in irrigation water. Seven cultivars of Hiemalis begonias (Begonia×Hiemalis) grown in soil infested with F. foetens were highly susceptible. No other Begonia species showed typical symptoms of chlorosis and wilt, but two cultivars of Rex begonia (Begonia rex) exhibited significant stunting in repeated trials. 相似文献