热水预处理对草莓室温贮藏品质的影响

研究了35～45℃热水预处理对贮放于室温（20±2）℃条件下丰香草莓果实品质及生理特性的影响。结果表明,适度热水处理可以明显地抑制草莓果实花青素积累,降低果实失重率、腐烂指数以及呼吸速率,维持较高的VC含量及超氧化物歧化酶（SOD）活性,降低纤维素酶活性、超氧阴离子（O2＾-）产生速率和丙二醛（MDA）含量,且明显地延长室温条件下果实贮藏寿命。其中40℃热水处理效应最好,在试验结束（144h）时果实失重率、腐烂指数以及呼吸速率仅相当于对照果实的58．9％、18．4％、51．0％。     

壳聚糖对草莓冷藏和货架期间品质的影响

以"达赛莱克特"草莓为试材,研究1%壳聚糖处理的草莓果实在0℃低温贮藏7 d后20℃常温货架6 d期间的品质变化规律。结果表明:与对照(0.1%醋酸溶液处理)相比,壳聚糖处理降低了低温贮藏后期和货架期草莓果实的呼吸速率、花青素、类黄酮及酚类物质的含量,保持较高的果实硬度,显著减少了货架期草莓果实腐烂和霉菌的发生,对果实失重率和可溶性固形物含量无显著影响。表明1%壳聚糖处理可有效延缓草莓的采后衰老进程,延长果实的货架期。     

不同贮藏条件对草莓贮藏品质的影响

为提高草莓的贮藏品质,寻求适合草莓的贮藏条件,将新鲜草莓分别置于常温阴凉（20 ℃）、冷藏库（0 ℃和-3 ℃）条件下贮藏7 d,每天测定草莓的可溶性固形物、可滴定酸、VC含量,同时监测失重率、腐烂指数和感官品质,研究不同贮藏条件对草莓品质的影响。结果表明：贮藏期间,冷藏库0 ℃贮藏草莓的可滴定酸和VC含量高于冷库-3 ℃和常温20 ℃贮藏的草莓,0 ℃贮藏7 d的草莓可滴定酸和VC含量分别为0.58%、29.8 mg/100 g;贮藏7 d时,-3 ℃贮藏草莓的可溶性固形物含量高于0 ℃和20 ℃处理,失重率和腐烂指数最低,分别为8.41%、8%、9.93;贮藏期间,0 ℃和-3 ℃贮藏草莓的感官品质均较好,优于20 ℃贮藏的草莓。综上可得,冷藏库0 ℃和-3 ℃贮藏草莓的品质优于常温20 ℃贮藏的草莓;冷藏库-3~0 ℃低温贮藏有利于保持草莓的品质,且避免草莓冻害。该研究可为草莓贮藏保鲜技术的研发提供参考。     

磷脂酶D抑制剂处理对草莓果实采后品质的影响

【研究目的】该文对磷脂酶D抑制剂-LPE（溶血磷脂酰乙醇胺）处理采后“达赛莱克特”草莓果实品质的影响的研究,以探索保持草莓采后品质、延长其贮藏期的新措施;并为非呼吸跃变型果实采后贮藏保鲜提供新的思路。【方法】采用25μM LPE、75μM LPE浓度的磷脂酶D抑制剂LPE处理草莓果实,设对照,放入4℃低温条件下贮藏。通过对草莓果实可溶性固形物含量、超氧阴离子含量、呼吸速率、可滴定酸含量、维生素C含量的研究表明：【结果】25μM LPE处理后的草莓果实可溶性固形物含量较高,降低了呼吸速率,维持较低超氧阴离子含量,贮藏后期保持了较高水平的维生素C含量和较低水平的可滴定酸含量,与75μM LPE处理和对照相比,较好地保持草莓果实采后品质,具有一定的保鲜效果。【结论】磷脂酶D抑制剂LPE处理有利于草莓果实采后品质的保持,且其作用效果受处理浓度的影响。     

不同品种草莓采后生理及贮藏特性研究

以甜查理、红颜和章姬3个品种草莓(Fragaria ananasa Duch.)为试材,研究比较了0~1℃环境下各品种草莓采后生理和果实品质变化。结果表明,贮藏期间3个品种草莓的呼吸强度、乙烯释放速率和失重率均呈上升趋势,果实硬度、主要营养物质含量呈下降趋势;甜查理果实硬度、主要营养物质含量、呼吸强度、乙烯释放速率和失重率均高于红颜与章姬,结合贮藏过程中好果率的变化,贮藏7 d时,甜查理好果率达97.58%,而红颜和章姬仅为62.82%和57.87%,甜查理耐贮性较好。     

乙醇缓释气体处理对草莓常温保鲜效果的影响

采用不同剂量（0、1．8、3．6、7．2g）的乙醇缓释剂处理新鲜草莓,用聚乙烯保鲜袋（180mm×280mm,厚度0．03mm）包装后。分别于室温（20±2）℃下避光贮藏7d,研究乙醇缓释气体处理对草莓保鲜效果的影响。结果表明．常温条件下．乙醇缓释气体处理能够有效抑制草莓的腐烂,延缓果实硬度、水分、VC含量和可滴定酸含量的下降．乙烯产量及呼吸强度在贮藏期内均显著小于对照。与传统的使用乙醇浸泡处理或乙醇熏蒸处理方法相比．采用缓释技术能够使极低剂量的乙醇气体持续缓慢地释放到贮藏空间内．在延长果实货架期的同时．能够避免传统方法处理时果实产生的类似酒精发酵的异味。使草莓保持正常的口感与风味。该方法操作简单,成本低廉．且安全无毒副作用,具有较高的推广应用价值。     

贮藏温度对早熟甜瓜采后生理及品质变化的影响

本文以早熟甜瓜品种‘早黄蜜’为试验材料,贮藏在不同温度（25℃、20℃、15℃、10℃、5℃）条件下,研究贮藏温度对果实生理及品质的影响。结果表明：低温贮藏明显降低甜瓜果实的呼吸速率、乙烯产生速率,同时推迟呼吸、乙烯高峰出现的时间。低温贮藏显著延缓果实硬度的降低,延长贮藏期。贮藏温度在贮藏期内对果实可溶性固形物含量的影响较小。早熟甜瓜贮藏在5℃条件下,贮藏19天出现冷害症状,不能正常后熟。‘早黄蜜’甜瓜在10℃条件下贮藏既能延缓成熟,又能正常后熟。     

不同货架温度对冰温贮藏红富士苹果品质的影响

红富士苹果冰温、0℃下贮藏5个月、7个月后分别移入不同温度货架,对果实感官及营养品质进行比较研究。结果表明,与0℃贮藏相比,5个月、7个月冷藏及货架期,冰温贮藏保持了红富士苹果较好的贮藏期及货架期品质。5℃货架温度较15℃下果实失重、硬度、可溶性固形物含量、可滴定酸含量下降缓慢,果面h值增加及果肉L*值下降减缓,花色苷、类黄酮、总酚含量损失率低。果实的营养品质较感官品质在较高的货架温度下损失率更高。因此,适宜的低温贮藏及货架温度可有效保持果实的感官及营养品质。     

温度波动对草莓贮藏和货架期品质的影响

以草莓"红颜"为试验材料,通过对草莓果实恒温冷藏和温度波动贮藏对比试验,研究温度波动对草莓贮藏期和货架期品质的影响。结果表明,在温度波动冷藏环境下,贮藏24 h和货架期12 h,草莓果实的品质显著差于恒定温度冷藏。温度波动不利于保持草莓果实贮藏期和货架期的品质。     

臭氧处理对草莓贮期果实品质的影响

以优质草莓为试材,研究了臭氧处理对草莓贮藏期间品质变化的影响。结果表明,草莓在(2.0±1.0)℃下贮藏,每隔3 d采用质量浓度300 mg/m3的O3处理0.5 h,能有效保持果实可溶性固形物含量和可滴定酸含量,降低果实呼吸强度和腐烂率,较好地保持果实硬度。适宜的臭氧处理对草莓有良好的保鲜效果。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Relation between wheat-rye crossability and seed set of common wheat after pollination with other species in the Hordeae

Summary Cultivars of common wheat (Triticum aestivum L. em. Thell.) of high wheat-rye (Secale cereale L.) crossability set more seed with pollen of other related species than did wheats of low wheat-rye crossability. This was found to be true for pollen parents from the genera Triticum, Aegilops, Secale, Agropyron and Elymus.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Inheritance of fruit colour in a wild Russian red raspberry seedling

Summary A new gene, i, from a self-incompatible wild Russian Rubus idaeus seedling is described. The gene i interacts with the fruit colour gene T, Tii plants having apricot instead of red fruits, and spines, leaves and stems pigmented to varying degrees. A deficit of apricot-fruited seedlings in progenies segregating for i could be explained by linkage between i and the self-incompatibility S locus with a crossover value of approximately 26.7%.Segregations for spine colour in crosses and backcrosses of the Russian seedling with two green-spined (ttII) raspberries selected for their yellow fruit colour, showed that both the latter carried the spine colour intensifier gene P. This suggests that earlier authors were incorrect in attributing the apricot fruit colour developed by some tt plants to a pleiotropic effect of P.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.