Water loss and postharvest characteristics of cut roses grown at high or moderate relative air humidity

Single node cuttings with one mature leaf were taken from the rose cv. Baroness and rooted in water culture. The rooted stems were kept in water culture and subjected to one of the two levels of relative air humidity (RH) (high: 90%, moderate: 70%) in climate chambers. Morphological characteristics, dry weight (DW), osmotic concentration, hemicellulose, cellulose and lignin content in the pedicel and vase life behavior were studied, as well as water loss. Only negligible differences in growth and morphology were found. No clear difference in lignin, hemicellulose and cellulose content in pedicels was found between moderate and high RH grown roses. Uncontrolled water loss was characteristic for leaves from high RH roses. Base treatment with AgNO₃ improved vase life of high RH roses from 7 to 12 days. Moderate RH roses lasted on average 15.5 days, and vase life was only slightly improved with the use of AgNO₃. Preservative solutions caused crispy areas between the veins and brittle leaves on roses grown at high but not at moderate RH. A 10% lower osmotic concentration in leaves and flowers was found in roses grown at high RH, as compared to moderate RH. It is concluded that the shorter postharvest life of high RH flowers is mainly due to malfunctioning stomata.     

Effects of air humidity and K/Ca ratio in the nutrient supply on growth and postharvest characteristics of cut roses

Single node cuttings with one mature leaf were taken from the rose cv. Baroness and rooted in water culture. The rooted plants were grown in nutrient solutions and subjected to two levels of relative air humidity (RH): high (90%) and moderate (70%), in combination with high (12/1), medium (1/1) and low (1/5) K/Ca ratios in the nutrient solution. High RH plants accumulated less Ca in leaves and flowers than moderate RH plants. Roses grown at moderate RH had a longer postharvest life than high RH roses, irrespective of the K/Ca ratio of the nutrient solution. In general, a high K/Ca ratio had a negative impact on postharvest life. When grown at a high K/Ca ratio the ornamental value declined rapidly, mainly due to the appearance of necrotic petals as well as chlorotic and necrotic areas on the leaves. Bent neck occurred only with high RH plants but changes in the K/Ca ratio had no differential effect. Dry spots and brittle leaves were observed on high RH roses, and the occurrence increased with increased K/Ca ratio in the nutrient solution. Stomatal conductance increased in parallel with increases in RH and K/Ca ratio when measured on intact roses placed in dry air (40% RH).     

The effect of water availability and quality on photosynthesis and productivity of soilless-grown cut roses

Low matric and to a lesser extent osmotic potential reduce significantly leaf area and rose yield. Net assimilation rate and transpiration are also negatively affected although less dramatically. Low water potential causes an increase in the water use efficiency of greenhouse roses when tested in closed, no-discharge systems. When a stable osmotic potential is maintained in open systems, using increased leaching fraction (LF), low osmotic potential results in lower water use efficiency. Osmotic potential in porous media serving for greenhouse cut-rose production is usually lower than the matric potential. However, low matric potential in porous media is usually accompanied by very low unsaturated hydraulic conductivity, causing localized zones of very low matric potential adjacent to the root–medium interface. This phenomenon, that cannot be measured using tensiometers, is the main limiting factor to water uptake by plant roots. Restricted water uptake results in low leaf water potential and cessation of leaf and shoot expansive growth.Combined effects of drought and salinity on photosynthesis have been studied for a number of agronomic crops but studies on roses have been limited. In most greenhouse crops a close relationship between total water potential in the root zone (Ψ_t^soil) and in the shoot (Ψ_t^shoot) is found and there are good indications about the plant’s ability to make osmotic adjustments in order to lower Ψ_t^shoot and prevent excessive water losses from the leaves thus maintaining the plant’s turgidity. Future studies conducted with roses can provide a better insight into the adaptive processes within the plants when exposed to salt or water stresses.     

SA对温室甜瓜白粉病预防效果的影响

新疆甜瓜在生长期受到各种病害特别是白粉病的影响,而传统的农药防治不但污染环境,而且影响人畜安全。植物抗性诱导剂SA(水杨酸)是一类新型的生物农药,可激发植物免疫系统,达到防病的目的。采用不同浓度SA溶液在甜瓜植株开花前1周、雄花开花后10 d、采收前10 d进行处理,在处理后3、6、9 d取新鲜的叶片测定其PAL、PPO和POD活性,处理后6 d调查病情指数,待果实成熟采收后测定产量、单瓜质量、可溶性固形物含量、果肉硬度及维生素C含量。结果表明,不同浓度SA处理均增强了PAL、PPO和POD活性,以100μg·m L~(-1)SA处理效果最好,随着处理时间的延长,POD和PPO活性均呈现了先升高后降低的趋势,而PAL活性则呈现出了逐渐降低的趋势。通过差异显著性分析,POD活性在处理后6 d时差异达到显著水平,PPO和PAL活性在处理后3 d时达到显著水平。通过采收后测定产量、单瓜质量、可溶性固形物含量、果肉硬度及维生素C含量,100μg·m L~(-1)SA处理能有效减少白粉病对哈密瓜产量和品质的影响。     

Maintaining product quality in raisins throughout the introgression of powdery mildew resistance

The availability of powdery mildew-resistant raisin accessions will lower grower production costs and enhance the environment through reduced fungicide use. To achieve this objective, backcrossing has been employed with Vitis romanetii as the source of non-race-specific powdery mildew resistance. Initial crosses of powdery mildew-resistant F₁ hybrid B36-45 with seeded raisin cultivars ‘Rangspray’ and ‘Raisin de Palestine’ yielded seedless powdery mildew-resistant first-generation backcross selections C87-41 and C87-106, which were used to develop second-generation backcross populations. Principal component analyses consistently identified ‘wrinkle,’ ‘meatiness,’ ‘product attractiveness’ and ‘skin persistence’ as being the quality characteristics most important in discriminating among powdery mildew-resistant raisin accessions and commercial raisin cultivars. Raisin quality ratings were much improved across most evaluated characters in second-generation backcross families as compared with parental powdery mildew- resistant accessions C87-41 and C87-106. After two generations of backcrossing, powdery mildew-resistant raisin selections were identified with product quality characteristics similar to those of commercial raisin cultivars.     

南瓜白粉病研究进展

南瓜白粉病是南瓜作物生产上最主要的病害之一,严重影响南瓜的产量和品质,制约产业的经济效益和瓜农生产积极性.目前,国内外对南瓜白粉病菌研究较少,对南瓜白粉病的防治手段较为单一.笔者过对国内外南瓜白粉病的发病规律、抗白粉病种质资源现状、分子生物学研究现状、白粉病防治等方面的研究结果进行综述,以期为南瓜生产和白粉病防治相关研...     

苦瓜白粉病与霜霉病的防治

近几年在苦瓜种植生产中,常出现叶片上褪绿黄斑逐渐扩大,导致病斑成片,叶片干枯,造成植株生长不良,减产失收的现象,这主要由霜霉病或白粉病引起的。苦瓜霜霉病主要为害叶片,初期出现浅黄色小斑。后扩大,病斑受叶脉限制呈多角形和不规则形,颜色由黄色渐变成黄褐色至褐色,严重时病斑融合为斑块。湿度大时,叶背长出白色霉状物,但天气干燥时很少见到霉层。苦瓜白粉病严重时也出现褪色黄斑,与霜霉病十分相似。白粉病除为害叶片外,还为害叶柄和茎。初期多在叶面或嫩茎上出现白色霉点,后扩展为霉斑。严重时霉斑连成大片,甚至布满叶面和叶背。秋天干…     

甜瓜抗白粉病育种研究进展

综述了葫芦科白粉病菌的种类、特征及其分布,重点介绍了主要危害葫芦科作物的2个白粉病的特点和其鉴定,甜瓜白粉病菌生理小种的分化和通用甜瓜鉴别寄主对这些不同生理小种的抗感反应,对抗源的发掘、抗性遗传与抗病育种进行了详细的评述,并提出了今后我国甜瓜白粉病研究的方向。     

杂交榛子对白粉病的抗性及防治技术研究

榛子白粉病是一种真菌性病害,主要危害榛树的嫩叶和果苞。近年来发生逐渐加重,若不及时防治,常引起树体营养贮藏少,树势衰弱,花芽分化差,     

切花月季的水分生理与灌溉管理

1　水分的生理作用水是植物体的重要组成成分 ,不但参与植物的生理代谢 ,也是代谢产物的运输载体 ,起着维持植物形态和姿态的重要作用。植物体内的水分含量一般占植物体质量的 70 %～90 % ,缺水会直接影响植物的生长发育和活性。早在 1975年 ,Plaut与Aikin等人就测定了月季植株     

硅化物处理对甜瓜白粉病的抑制效果

以玉金香甜瓜幼苗为材料研究不同硅化物对白粉病的抑制作用,结果表明:硅化物处理浓度较高时,对甜瓜幼苗叶片有一定的药物伤害,相同浓度条件下,硅酸钠伤害最大;其次为正硅酸;纳米氧化硅伤害最小。硅酸钠、正硅酸和纳米氧化硅能显著降低白粉菌初生芽管的萌发,并能显著提高甜瓜对白粉病的抑病率。3种硅化物处理可显著降低甜瓜白粉病的严重度,提高对白粉病的防效,其中硅酸钠防效最高;其次为正硅酸;纳米氧化硅防效最低。硅酸钠处理可显著提高过氧化物酶(POD)和β-1,3葡聚糖酶(GLU)的活性,起到诱导抗性作用;纳米氧化硅处理对POD活性没有影响,不具有诱导抗性作用。     

Genetic basis of powdery mildew resistance in muskmelon

A study was undertaken to investigate the inheritance of powdery mildew resistance in muskmelon grown on river beds, under natural epiphytotic conditions. ‘Campo’ and ‘PMR 6’ were selected as resistant parents, ‘Gulfstream’ as moderately resistant and ‘Lucknow Safeda Selection’ as susceptible parents. The genotypes of the two resistant parents have locus/loci which are similar in conferring resistance. The moderately resistant parent might have an allele at least in one locus different from that in the resistant parent. Two effective factors were found to be differentiating disease reaction between the susceptible and the resistant parents. The direction of the genetic effects showed that it is possible to get from the cross between the susceptible and resistant parents, segregants with the desired level of resistance.     

温室草莓白粉病防治技术

草莓作为经济价值较高的小浆果,因其味美营养价值高．深受人们喜爱。目前我国草莓的栽培面积已达6万hm^2,位居世界第1位。近年来,温室草莓白粉病发病强度呈逐年加重的趋势．一经发生很难防治,一般减产20％～30％,重者可达50％．严重影响草莓的产量和品质．已经成为我省温室草莓生产的重要病害。     

梨白粉病防治技术要点

梨白粉病(Phyllactinia pyri[Cast]Homma)主要危害叶片,在河北、辽宁、山西、陕西等地梨产区常有发生,严重时造成早期落叶。与梨黑星病、梨黑斑病相比,梨白粉病的发生一直未被重视。随着环境条件的改变,病害的危害也发生变化。在河北省冀东地区,春季梨白粉病较少发生,主要发生在秋季,生产中主要集中在果实采收前防治,多数梨园在果实采收后对白粉病的防治不够重视。近年来常出现高温干旱天气,使得梨白粉病的发生呈逐年加重的趋势,大量梨树发生早期落叶,造成二次发芽,对产量、树势影响极大。已成为梨树主要病害之一。     

Effectiveness of whey against zucchini squash and cucumber powdery mildew

The effectiveness of whey against powdery mildew (Podosphaera xanthii) of cucumber and zucchini squash was tested in greenhouse experiments. Plants were sprayed once or twice a week with whey at concentrations of 0, 5, 10, 15, 20, 25, and 30% in water. Severity of powdery mildew was estimated weekly by visual assessment of individual leaves and scored as percentage of leaf area affected. Effectiveness of treatments did not differ significantly when applied weekly compared to twice a week. In each instance, powdery mildew severity correlated negatively with whey concentration. For cucumber, the rate of the disease progress in the control ranged from 0.45 to 0.75. Disease progressed more slowly in plants treated with 25–30% whey than when lower concentrations were used. The rate of disease progress varied from 0.12 to 0.33 in plants treated once a week and from 0.13 to 0.17 when applied twice a week. Similar tendencies were observed for zucchini, but disease progressed more rapidly and the final disease severity was higher than in cucumber. Effectiveness of whey applied twice a week at concentrations of 15–30% did not differ significantly among treatments; in these treatments the rate of disease progress was about 0.23 and significantly higher than the value for the water controls (about 0.80). Plants treated with 30% whey often exhibited symptoms of phytotoxicity. The data indicated that whey effectively controlled powdery mildew in cucumber and zucchini. Further studies are needed to optimize the concentration and timing of whey applications for mildew management in commercial crops.     

瓜类蔬菜白粉病抗性诱导及抗性遗传研究进展

瓜类蔬菜作为世界各地重要的蔬菜种类,多年来深受白粉病危害和影响,抗性诱导是减轻其危害的有效技术途径.笔者简要概述了瓜类白粉病抗性诱导及抗性遗传的研究进展,主要从生物因子、化学因子和物理因子诱导途径,以及瓜类白粉病抗性基因和抗性分子标记开发与应用等方面综述了近年来的研究成果,并对今后的研究方向提出展望.     

甜瓜白粉病及其抗性分子遗传研究进展

甜瓜是世界范围内重要的水果型蔬菜,但其产量和品质严重受到白粉病的影响。选育和推广抗白粉病甜瓜新品种是从根本上绿色、环保地解决白粉病危害甜瓜生产最为有效的方法,对甜瓜白粉病菌及其寄主抗性分子遗传机制的研究是加快抗病品种选育的前提和基础。笔者综述了甜瓜白粉病病原菌种类和分布、抗性遗传和抗性基因、生理小种的鉴别、白粉病菌的基因组特征,根据研究现状展望未来研究方向,以期为甜瓜抗白粉病育种提供借鉴和参考。     

保护地栽培草莓白粉病的防治

保护地栽培草莓 ,极易发生白粉病 ,常造成一些经济损失。笔者在多年实践中摸索了一点经验 ,供同行和广大草莓种植者参考。1　选育无病秧苗脱毒苗抗逆性强 ,具有生长健壮、产量高、效益好的优点。如果自己育苗 ,应选择生长健壮无病且结果多而大的母苗带土植于繁殖圃 ,培育健壮子苗。2　苗期防治繁殖秧苗的中前期 ,用世高、仙生或硫制剂防治均可。 8月中旬以后 ,病菌开始逐渐转向越冬状态 ,很少发现病叶 ,但千万不能疏忽 ,一定要在定植前细致周密地喷一遍杀菌剂 ,以减少越冬病菌。可选用 50 0 0倍世高、60 0倍仙生、4 0 0倍硫悬浮剂或 60 0倍…     

Vascular blockage in cut roses in a suspension of Pseudomonas fluorescens

Summary

To analyse quantitatively the relationships between cut rose (Rosa hybrida L. ‘Pascha’) vase-life, the onset of cavitation, plant water potential, and bacterial concentrations in the vase water, rose stems were placed in water containing different concentrations of Pseudomonas fluorescens 2892 tet^r rif ^r. There was a significant correlation (P = 0.0009) between cut rose vase-life and the concentration of bacteria in the vase water. As the number of bacteria in the vase water increased, the rate of senescence also increased. The water potential for roses in the bacterial suspension (at 8.50 log₁₀ CFU ml^–1) proceeded to drop constantly after 5.17 h in the vase solution, with the water potential falling to as low as -2.35 MPa by the end of the experiment (at 117 h). In contrast, the water potential of roses in deionised water dropped from -0.419 MPa at 5.17 h, to only –0.663 MPa after 117 h. When roses were stood in a bacterial suspension (at 8.5 log₁₀ CFU ml^–1) for 30 h, 63.8% of the total cumulative cavitation events were seen, while roses stood in deionised water exhibited only 26.8% of the total cavitation events. Uptake of acid fuchsin and the movement of tagged P. fluorescens 2892 in the xylem indicated that bacteria did not travel beyond the open-ended xylem vessels and were generally restricted to the first 50 mm from the cut end of the stem.