部分葡萄品种和砧木抗葡萄根瘤蚜性能鉴定

为了检测我国葡萄品种和砧木对中国生态型葡萄根瘤蚜Daktulosphaira viticola (Fitch) 的抗性,在实验室条件下采用离体根接种法鉴定了10个葡萄砧木、18个葡萄栽培品种,测定了根瘤蚜存活率、发育历期、产卵量、种群龄期结构指数和成虫大小等指标。结果表明： 砧木品种SO4,5BB,1103P,420A,Lot,101-14MG,3309C,140Ru和110R抗根瘤蚜,接种后蚜虫陆续死亡,尤其是SO4,5BB,1103P和420A对根瘤蚜高抗,使根瘤蚜滞育仅发育至1龄。我国当作砧木使用的贝达不抗根瘤蚜,接种后蚜虫存活率始终保持在38.82％～47.5%,日产卵量达9.01;欧美杂交种中的康克、康拜尔和卡它巴对根瘤蚜稍有抗性,根瘤蚜日产卵量在6.00～6.85粒之间,其中康克、康拜尔葡萄上蚜虫的存活率随时间的延长而明显降低,由最初的60％下降至25％～30％; 欧美杂交种中的黑虎香和白香蕉虽然在一定程度上能够限制根瘤蚜的存活和发育进程,但对根瘤蚜的繁殖量没有影响。所有供试欧亚种和欧美杂交种的栽培品种都对根瘤蚜高度敏感,接种后第29 d 蚜虫存活率仍保持在40％～60％,且前后变化较小,日产卵量变化于7～12.35粒之间,总产卵量均在190粒以上。由此可见,我国供试栽培品种均不抗根瘤蚜,在根瘤蚜疫区需要用抗性砧木嫁接苗建园。     

柑桔砧木矮化特性分类研究

以３１种柑桔砧木为试材,对根皮率,根导管总面积,栅海比,叶片气孔密度,茎还原性糖含量,叶片还原性糖含量,叶片氨基酸含量,茎蛋白质含量,叶片过氧化物酶活性９个柑桔砧木矮化预选指标进行测定,采用聚类分析的方法,将这些砧木分为矮化砧,半矮化砧、半乔化砧、乔化砧４类。     

尖叶木樨榄作砧木嫁接油橄榄的研究

本文就云南、四川两省采用尖叶木樨榄(Olea ferrugineaRoyle.)作砧木嫁接油橄榄(Olea europaea L.)二十余年的试验观察,报道尖叶木樨榄在我国的分布及其生物学特性,系统总结尖叶木樨榄作砧木对油橄榄生长发育及开花结实的影响。试验结果表明:尖叶木樨榄作砧木具有种子出苗率高,嫁接繁殖容易,提早油橄榄开花结实年龄,增强油橄榄对酸性红壤的适应性,增强油橄榄对干旱环境和对某些病害的抗性等优点。此砧木已在我国西南部油橄榄适生区应用于生产性栽培。     

Histological study of initiation and development in vitro of adventitious roots in minicuttings of apple rootstocks of M 26 and EMLA 9

Apple rootstocks M 26 and EMLA 9 'COST' shoots propagated in vitro were used for the histological study of initiation and development of adventitious roots after a brief induction pretreatment. The results show that there are differences in mode and timing of initiation and development of adventitious roots between the two varieties. In M 26, adventitious roots were directly initiated from the derivatives of the cambium, some of which were immediately transformed into meristemoids in situ 36 h after pretreatment. Subsequently, meristemoids differentiated into root primordia. Development of adventitious roots were completed when they emerged at the surface of stem bases 10 days after pretreatment. In EMLA 9, before the meristemoids formed, internal cell files were formed by continuous divisions of cambial cells. The cells were regularly arranged in files external to the cambium. On the fourth day after pretreatment, some cells in the outermost layers of these files became meristematic, started to divide and turned into meristemoids, which differentiated into root primordia. The cells of the files between the root primordium and the cambium were transformed into vascular tissues which connected the vascular systems of the adventitious roots and stems.     

The induction of hexaploidy in cherry rootstocks using in vitro regeneration techniques

Summary An in vitro regeneration technique using root callus has been combined with colchicine application to produce hexaploid plants from the sterile triploid cherry rootstock Colt. Colchicine (50 mg/l) was applied together with auxin (IBA) (3 mg/l) either before or after root primordium formation in single excised micropropagating shoots. In both cases shoots were regenerated in vitro from the putative hexaploid roots. Both methods produced hexaploid plants but more than 70% of the regenerated clones were still triploid. The hexaploid plants were distinguishable from the triploids on morphological as well as cytogenetic grounds. Quantitative characters such as leaf length/breadth ratio, stomatal length and density in the hexaploids were significantly different from both regenerated and non-regenerated triploids.     

Virulence of Meloidogyne spp. and Induced Resistance in Grape Rootstocks

Harmony grape rootstock displays resistance to several Meloidogyne spp. but that resistance is not durable in commercial vineyard settings. A 2-year experiment in a microplot setting revealed host specificities of two virulent populations of Meloidogyne arenaria and an avirulent population of Meloidogyne incognita. In a subsequent split-root experiment, the avirulent nematode population was demonstrated to induce resistance to the virulent nematode population. To quantify the level of resistance, reproduction of the virulent nematode population was determined 63 days after being challenged by an avirulent nematode population using a range of inoculum densities and timeframes. Induction of resistance became apparent when the virulent nematode population was inoculated 7 days after the avirulent nematode population and increased thereafter. The level of induced resistance increased with increased inoculum levels of the avirulent nematode population. Root systems of perennial crops are commonly fed upon simultaneously by multiple nematode species. These two studies indicate that field populations can become preferentially virulent upon one or multiple rootstocks and that co-inhabiting populations may induce existing resistance mechanisms. In perennial crops, it is common for numerous nematode species besides Meloidogyne spp. to be present, including some that feed without causing apparent damage.     

In vitro Micrografting of Mature Pistachio (Pistacia vera var. Siirt)

The success of various in vitro micrografting methods of shoot tips of pistachio (Pistacia vera L. var. Siirt) have been examined. Excised zygotic embryos that germinated in vitro were used as rootstocks. Current year shoot tips from mature trees of pistachio micrografted onto in vitro juvenile rootstocks, resulted in the restoration of shoot-bud proliferation. Variables tested include a size of microscion, grafting method, effects of culture medium and effects of time of the year at which shoot tips were used. The results indicate that the easiest and most successful method for grafting was slit micrografting. High levels of micrograft take were achieved with 2–4 mm (56.75%) and 4–6 mm (79.25%) long scions obtained from the regenerated shoot tips. The survival rate of the shoot tips was directly related to time of the year. The best growth of microscion was obtained with the in vitro forced shoot tips rather than with shoot tips excised from tree. Slow growth and lack of axillary shoot development on the micrografts was noticeable when the micrografts were cultured on hormone-free and germination medium. In vitro micrografted plantlets were successfully weaned and no problems were encountered with the establishment of micrografted plants in vivo.     

Phylogeny analysis of 25 apple rootstocks using RAPD markers and tactical gene tagging

RAPD (random amplified polymorphic DNA) markers were used to fingerprint eight commercially available apple rootstocks (Nertchinsk, Northern Spy, Osman, Heyer 12, M.1, M.9, M.26 and MM.106), 10 winter hardy offsprings derived from the cross of Nertchinsk x M.9, six winter hardy offsprings derived from the cross of Nertchinsk x M.26 and one winter hardy offspring derived from each of the two crosses between Osman x Heyer 12 and Northern Spy x M.1. Phylogeny analysis using parsimony allowed us to draw the genetic relationship between these lines using only RAPD markers data. The resulting cladogram was compared to the true genetic relationship between these lines in order to assess the efficiency of RAPD markers in determining accurately the phylogenetic relationship. We also developed a DNA fingerprinting system based on 13 informative RAPD loci amplified by five RAPD primers that allowed the rapid identification of apple rootstocks.     

Effect of low doses of gamma irradiation on in vitro growth of grapevine

Shoot tips and single node explants of two rootstocks (R.99 and 3309) and two varieties (‘Helwani’ and ‘Cabernet Franc’) of grapevine cultured on DSD1 media for a period of 60 days, were irradiated with 0, 2, 5 and 7 Gy doses of gamma irradiation. Shoot length of ‘Helwani’ and ‘Cabernet Franc’ was increased by 7 Gy irradiation. The 5 Gy dose increased the number of roots in plants of the two rootstocks and ‘Helwani’. Root length of ‘Helwani’ and ‘Cabernet Franc’ at the 2 and 7 Gy doses were significantly higher than those of the non-irradiated control. A similar effect was noticed on R.99 rootstock subjected to 5 Gy. Five Gy also increased the dry weight of the R.99 rootstock, whereas 2 and 7 Gy had a similar effect on ‘Helwani’ and ‘Cabernet Franc’. Number of leaves of plants exposed to 5 and 7 Gy was increased when compared with the non-irradiated control. This revised version was published online in June 2006 with corrections to the Cover Date.     

Reproductive Variability of Field Populations of Meloidogyne spp. on Grape Rootstocks

Variability in penetration, development, and reproduction of two resistance-breaking field pathotypes (pt.) of Meloidogyne arenaria, M. incognita, and a population of mixed Meloidogyne spp. virulent to grape hosts were compared on two resistant Vitis rootstocks ''Freedom'' and ''Harmony'' in separate tests. ''Cabernet Sauvignon'' was included as a susceptible host to all four nematode populations. Secondstage juveniles (J2) of the mixed population failed to penetrate Freedom roots. By contrast, 6% of J2 in the M. incognita population penetrated Freedom roots but did not develop beyond the swollen J2 stage. The two resistance-breaking populations of M. arenaria differed in their virulence except on susceptible roots of Cabernet Sauvignon. More J2 of M. arenaria pt. Freedom penetrated Freedom roots and reached adult stage than did M. arenaria pt. Harmony. Later life stages of M. arenaria pt. Freedom occurred earlier and in greater numbers in Harmony roots than did M. arenaria pt. Harmony. Reproduction of M. arenaria pt. Freedom was greater in Freedom and Harmony roots than M. arenaria pt. Harmony. Thus, one population of M. arenaria is highly virulent and the other is moderately virulent.