Observations of Phytophthora spp. in Water Recirculation Systems in Commercial Hardy Ornamental Nursery Stock

Samples of water and sediment were taken from drains, reservoirs and wells from four commercial hardy ornamental nurseries with water recirculation systems. The samples were taken on seven different dates throughout a single year from August 1994 to July 1995. The samples were screened for Phytophthora species using five different methods: direct plating, three bait tests (using lupin seedlings, apples and Rhododendron leaves) and a DAS-ELISA (double-antibody sandwich enzyme-linked immunosorbent-assay) with two antisera. In the nurseries with old water recirculation systems, Phytophthora species were detected in the drains and in the reservoirs. In the nursery with a new recirculation system, the pathogens were only present in the drains. None of the water samples from wells in any of the nurseries were contaminated. Phytophthora species were present in the water as well as in the sediment samples from drains and reservoirs. They were detected in the water recirculation systems irrespective of the season. The number of isolates increased about sevenfold between late summer and spring. At least 12 different Phytophthora species were identified: some isolates were previously unrecorded species. The epidemiology of the pathogens in outdoor water recirculation systems as well as the importance of the results for commercial nurseries is discussed.     

24种白三叶种质材料在长沙的适应性研究

本文对来自不同地区的24种白三叶种质材料进行对比研究,调查不同种质材料在长沙2013年夏季旱灾后的恢复情况和2014年“倒春寒”后各种质材料的存活及返青情况。结果表明,植株高度和匍匐茎长短与白三叶耐旱情况成正比,而干旱后返青速度越快的白三叶材料,遇到寒冷时死亡速度越慢。同时从中选出了三类适合于华中地区种植的材料类型,第一类为既耐旱又耐寒的02485和海发,第二类为较耐旱不耐寒,但返青速度快的02478、00858、CF022549和00605,第三类为不耐旱但耐寒、返青速度快的百事吉、和谐、贵州大方和02587。     

Identification of an ice recrystallisation inhibition gene family in winter‐hardy wheat and its evolutionary relationship to other members of the Triticeae

Ice recrystallisation inhibition (IRI) proteins are important for plants that exist in cold environments. Six novel genes encoding IRI proteins were isolated from winter‐hardy wheat (Tricticum aestivum) cultivar (Mironovskaya808). Conserved domain analysis confirmed that all the predicted proteins contained the basic characteristics of IRI proteins, including leucine‐rich repeats (LRR) and IRI‐domains (NxVx_1‐2G). In addition, these proteins possessed an N‐terminal signal peptide and some conserved cysteines. Despite the high conservation of the amino acid sequences, the characteristic regions still exist among these IRI‐domains of IRI sequences. All IRI sequences in this study are highly homologous with phytosulfokine receptors (PSR). Quantitative real‐time PCR (qPCR) analysis indicated that each member of the IRI gene family was induced after exposure to low temperature. Heterologous expression of IRI proteins enhanced freezing tolerance in host cells. A total of 28 IRI genes were isolated from Triticeae, and the evolutionary relationship of the IRI gene family in Triticeae and related species showed high interspecific specificity. The IRI genes from Aegilops, which is one of the progenitors of allohexaploid wheat, shared the closest relationship with those from Triticum. With high interspecific specificity in Triticeae, however, there was no specificity among different species of Triticum. Our results suggest that IRI genes have potential value to improve cold resistance of crops.     

抗寒优质梨新品种‘寒露梨’

‘寒露梨'(原代号77-23-272)是由‘延边大香水'ב杭青'种间杂交选育而成。果实黄绿色,短圆锥形,平均单果质量220g,肉质酥脆,多汁,酸甜,石细胞少,有香气,含可溶性固形物14%,可溶性糖9.01%,可滴定酸0.20%,维生素C0.0068mg·g-1,品质优,抗寒,抗病。     

苹果砧木组织结构特征与抗寒矮化效应的关系

通过对苹果砧木组织结构特征的研究表明，抗寒矮化砧的叶片气孔密度、根和茎的导管密度、茎的材皮比、根导管面积低于乔砧，叶片栅海比、茎导管面积高于乔砧，乔砧与抗寒矮砧的叶片上、下表皮厚、根材皮比无明显差异。扎矮76、小金海棠、GM256、77—34是抗寒矮化的苹果砧木。     

局部紧的Vilenkin群上的广义分数次积分算子

G表示局部紧的Vilenkin群．作者对Vilenkin群G上的标准分数次积分算子进行拓广，首次引入了在G上的θ型分数次积分算子，并对它进行了详细的研究．利用Hardy空间和Herz型Hardy空间的原子和分子分解特征，文中首先给出了此类算子从Hardy空间到Lebesgue空间上的有界性，而且，在满足一定的消失矩时，它又是Hardy空间上的有界算子．更进一步地，文章还讨论了这类算子在Herz型Hardy空间上的有界性．     

Intersubgeneric cross in Nymphaea spp. L. to develop a blue hardy waterlily

Five waterlily cultivars, with good pod setting and completely formed flowers, from the subgenus Nymphaea (hardy waterlily) were used as pod (female) parent. Waterlilies from subgenera Anecphya (2 entities) and Brachyceras (20 entities), specifically the blue-flowered ones, were used as pollen (male) parent for transferring blue-flowered characteristic to the hardy waterlily. Hybridization of subgenus Nymphaea with subgenus Anecphya was unsuccessful. A successful crossing was obtained between the subgenera Nymphaea and Brachyceras, yielding one pod with 244 seeds, from which only 39 seeds germinated and yielded 20 good intersubgeneric hybrid plants. The characteristics of the hybrids were categorized by their flower colors into two groups, a pink-flowered group with 17 hybrids and a blue-flowered group with 3 hybrids. In the blue-flowered group, there was a prominent one with beautiful blue-purple flower, which was determined by PCR-RFLP markers to be a hybrid between Nymphaea and Brachyceras subgenera, as well as inherited some plant characteristics, for example, ovary carpel, leaf (pad), rootstock, position of flower at flowering from the parent. The blue-purple flowered hybrid had important characteristics inherited from the hardy waterlily (subgenus Nymphaea); therefore, the hybrid has been named Nymphaea ‘Siam Blue Hardy’ to honor the birth place and its distinct flower color.     

梨新品种‘寒酥梨’

 ‘寒酥梨’是由‘大梨’ב晋酥梨’人工杂交选育而成。果实绿色、圆形,平均单果质量260 g左右,最大540 g,果形整齐,肉质酥脆,果汁多,石细胞少,味酸甜,可溶性固形物13.5%,可溶性糖8.83%,可滴定酸0.12%,维生素C含量0.0325 mg · g-1,品质优,抗寒、抗病能力强。     

Effect of High Lucerne (Medicago sativa L.) Sowing Rates on Establishment Year Yield, Stand Persistence and Forage Quality

The effect of very high sowing rates on establishment year dry matter (DM) yield and stand persistence of irrigated lucerne ( Medicago sativa L.) was studied. Two cultivars ('Peace' and 'Apollo II') were sown in 1986 at two row spacings and six sowing rates from 5.6 to 50.4 kg ha⁻¹. Established seedling density (S_d) increased linearly with sowing rate (R):S_d= 24.1R. Establishment year DM yield increased at sowing rates from 5.6 to 16.8 kg ha⁻¹, levelled off as sowing rate increased to 33.6 ka ha⁻¹, and then decreased as sowing rate increased further. Thus, there was a broad optimum sowing rate that gave a maximum sowing year DM yield. Percent plant survival to the third year (1988) decreased with increasing sowing rate so that plant densities became similar for sowing rates greater than 16.8 kg ha⁻¹. Within the range 5.6 to 16.8 kg ha⁻¹, increasing sowing rate increased stand persistence measured as 1988 plant density; however, a corresponding increase in DM yield was not obtained. For all full-production years, DM yield was independent of sowing rate. Sowing rate did not affect three chemical measures of forage quality.     

‘SJM15’ Apple Rootstock

ABSTRACT

The ‘SJM15’ Apple Rootstock is s a new dwarfing apple rootstock developed at the Agriculture and Agri-Food Canada (AAFC) Research Station, St-Jean-sur-Richelieu, Quebec. It produces dwarf trees equal to or slightly smaller than ‘Ottawa 3’ (O.3) and ‘Malling 9’ (M.9). It was released because of its superior hardiness, ease of propagation, and better efficiency compare to ‘O.3’.