山农丰抗棉6号种植密度整枝方式对产量的影响试验

山农丰抗 6号是山东农业大学农学院育成的高产、抗病、优质新品种抗虫棉 ,适宜盐碱地、覆膜、直播、春播、麦棉、瓜棉、菜棉套种。肥水、密度、整枝方式是影响该品种产量的主要因素 ,为找出最佳密度及与之相配套的整枝措施 ,2 0 0 1年 ,笔者在老僧堂乡进行了不同种植密度与整枝方式试验。1　材料与方法　　试验地有机质含量 1 2 1% ,速效氮 75mg kg ,速效磷 2 5mg kg ,速效钾 15 0mg kg ,棉花常规种植法 ,留苗密度 36 5 0 0株 hm2 株左右。试验设 6个处理 ,重复 3次 ,随机区组排列 ,小区面积 0 0 0 33hm2 ,等行距种植 ,0 4 2 0日播种。全…     

稀有植物矮杨梅种子繁殖试验

矮杨梅 (MyricananaCheval.)种子繁殖试验表明 :(1)当年收获种子基本无萌发能力 ;(2 )经低温 (4± 1℃ )层积或沙藏处理 8个月种子能萌发 ,前者发芽率低 (2 9.0 %) ,后者高 (6 7.5 %)。 (3) 6 0℃以上热水浸泡处理种子萌发率高 ;(4)种子在自然状态下不耐贮藏 ,经低温层积贮藏 2年的种子发芽率 (35 .4%)明显高于贮藏 3年种子 (8.2 %) ;(5 )矮杨梅是耐荫性植物 ,幼苗在遮荫条件下才能正常生长。     

高效蓄冷材料筛选与保鲜应用试验研究

为了筛选相变温度适宜和保鲜效果好的蓄冷材料,从而挑选出适宜不同蔬菜保鲜的蓄冷材料,选用水、4.8%氯化钠、10%乙酸铵和15%甲酸钠作为蓄冷材料,了解它们的热力学特性和对黄瓜、甜椒、生菜和西兰花4 种蔬菜的保鲜效果。结果表明：水、4.8%氯化钠、10%乙酸铵、15%甲酸钠的相变温度分别为0、-6、-12、-16℃,在-28℃冷冻条件下从液态到固态的相变时间分别约为6、12、11、18 h,在常温密闭条件下从固态到液态的相变时间分别约为15、6.5、6、7.5 h。4.8%氯化钠作为蓄冷材料对黄瓜、甜椒有较好的蓄冷保鲜效果;15%甲酸钠作为蓄冷材料对甜椒、生菜、西兰花有较好的蓄冷保鲜效果。在生产实践中,对于黄瓜、甜椒等喜温性蔬菜可采用4.8%氯化钠进行蓄冷保鲜,对于生菜、西兰花等半耐寒性蔬菜可采用15%甲酸钠进行蓄冷保鲜。     

细说尤伯球(下)

尤伯球的繁殖尤伯球可采用播种和把植株切顶促生子球然后再用嫁接的办法进行繁殖。播种时要注意:1.把握适宜的时间。播种时间以每年春季4～5月和秋季9月为宜。因为这样可以使前期细小的幼苗避开盛夏和严冬的危害,发育更顺利。2.播种介质使用前要严格消毒。3.细心呵护前期幼苗。尤伯球幼苗前期呈半透明状,十分脆弱,要特别注意保护,盆上不能太干,也不能太湿,浇水采用浸水法,注意遮荫,勤观察,适时喷洒一些灭菌药物。4.最好用新鲜种子插种。新采集的种子(采后1～2个     

不同遮荫条件对蛇皮果生长及生理特性的初步研究

蛇皮果是喜阴植物,遮荫处理对蛇皮果幼苗的生长具有重要作用,笔者研究不同遮荫处理对蛇皮果栽培生长的影响。本试验通过采用不遮荫（CK）、25%遮荫（S1）、50%遮荫（S2）、75%遮荫（S3）及椰子叶遮荫（S4）的处理方式对蛇皮果进行遮荫栽培研究。结果表明,不同处理对于蛇皮果的生长发育影响显著（P<0.05）,其中75%遮荫（S3）处理效果很好,其次是50%遮荫（S2）和椰子叶遮荫（S4）处理,遮荫处理对于蛇皮果的生长具有促进作用。遮荫栽培试验为蛇皮果规模化生产提供了重要的参考意义。     

遮荫网透光度对闽楠苗木生长影响的研究

为了解决闽楠苗木在全光照条件下存活率低的问题,采用遮荫40%、60%、70% 3种遮荫处理,以全光照为对照,进行对闽楠苗木保存率、苗高生长与地径生长的影响试验。结果表明：用遮荫网遮荫使保存率提高41~41.7个百分点,用遮光度为60%的遮荫网较适宜闽楠幼苗的生长,而全光照对闽楠苗期生长不利。     

玉米新品种垦玉 706 的选育

甘肃农垦良种有限责任公司以高产、抗病、抗倒为育种目标,2013 年选用自育系 LKF0601 为母本、LKMB-1 为父本进行杂交选择,育成发芽势强、拱土能力强、幼苗长势强、结实性好的中熟玉米新品种垦玉 706。该品种适宜在 4 月下旬地温≥ 10℃以上的东华北中熟春玉米区播种,以直播栽培方式选择中等肥力以上地块,种植密度 4500 株 /667m2 最为适宜。     

藏药铁棒锤种子发芽特性研究

研究了铁棒锤（Aconitum pendulum Busch）种子在光照和黑暗条件下不同温度（10、15、20、25、30℃和23／28℃变温）处理对发芽率、发芽势和发芽指数的影响。结果表明,铁棒锤种子千粒重为1．66g;最大吸胀率为125．0％,达到饱和吸胀需20h;黑暗环境下15℃有利于种子发芽,发芽率达30．3％,16天内平均发芽指数这1．54,但萌发后光照有利于形成健壮的幼苗。上述结果说明,土壤温度稳定通过15℃是铁棒锤的最佳播期,播种后应采用一定的覆盖遮荫措施,出苗后及时解除遮荫以促进根系发育。     

播期对小麦冬前幼苗生长和积温的调控效应

为了研究播期对小麦冬前幼苗生长和积温的调控效应,以‘光明麦1号’为试验材料,设计不同播期试验,旨在探讨播期对春性小麦冬前幼苗生长发育和积温的影响。结果表明,随播期推迟,出苗率下降,且冬前积温降低,显著影响小麦冬前生育进程,植株叶龄减小,分蘖发生数下降,LAI和干物质积累降低。播种至出苗阶段日均温与出苗天数呈指数相关关系,出苗至越冬始期≥0℃积温与此期天数、叶龄、茎蘖数、LAI和干物质积累呈显著线性正相关。本试验条件下,播期每推迟6天左右,播种至出苗日均温下降1.0~2.5℃,≥0℃积温上升5~15℃,播种至出苗所需天数延长2~5天,出苗至分蘖所需天数延长1~10天,出苗至越冬始期的天数缩短6~11天,出苗率下降1.5~3.5个百分点,越冬始期叶龄减少0.4~1.0,茎蘖数、叶面积指数和干物质积累分别下降100~150万/hm²、0.04~0.51和30~200 kg/hm²。实现春性小麦壮苗的冬前≥0℃积温为500~670℃,适宜播期10月23日—11月4日,最适播期是10月27日—10月29日。     

低温对不同虫态烟草甲的影响

利用低温处理方法,对不同虫态烟草甲进行处理。研究结果表明,各虫态烟草甲耐低温的顺序从高到低依次是:幼虫、成虫、卵。-20℃处理,各虫态烟草甲死亡率都为100%;-10℃低温条件下,处理1h以上,烟草甲卵和成虫全部死亡,处理72h以上,烟草甲幼虫全部死亡;5℃处理72h以上,烟草甲卵不再孵化,5℃处理20d不能使烟草甲幼虫和成虫完全致死,但影响幼虫化蛹和成虫产卵。各温度处理中烟草甲幼虫最终羽化率为0,成虫单雌产卵量为0。0℃,5℃卵最高孵化率均为41.67%。对照中幼虫最终羽化率为77%、卵最终孵化率为52%。     

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.     

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.     

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.     

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.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form. This revised version was published online in July 2006 with corrections to the Cover Date.