不同耐旱性玉米品种对干旱的生理生化反应

马秀芳等以耐旱性不同的3个玉米品种为试材，通过两年的盆栽试验研究了抽雄期水分胁迫下玉米的一系列生理生化指标的变化，探讨了这些指标与玉米耐旱性之间的关系。结果表明，水分胁迫下，相对含水量、SOD、CAT和POD活性下降，相对电导率、丙二醛、脯氨酸和可溶性糖含量升高。3个品种中，相对含水量与穗粒数呈显著或极显著正相关，其余各指标与产量构成因素之间的相关程度依品种而异。这些指标在确定品种耐旱方面可以作为参考。     

玉米穗期水分胁迫对产量和水分利用效率的影响

在盆栽条件下,以6个玉米杂交种为试验材料,研究了玉米穗期正常供水、轻度和中度水分胁迫下产量和水分利用效率(Water Use Efficiency,简称WUE)的变化.结果表明,6个玉米品种的产量和耗水量的水分胁迫效应均显著,随胁迫程度加大,产量和耗水量均明显降低,但不同品种对水分胁迫的反应存在差异.轻度水分胁迫下,供试品种中有两个品种表现出产量下降幅度不大、且比耗水量下降幅度小、WUE有所提高的优良特性;中度水分胁迫下,6个品种均表现为产量大幅度下降,且远高于耗水量的下降幅度,导致WUE明显降低.相关分析表明,3种供水条件下,WUE与产量均呈显著正相关,与耗水量的相关性均不显著.     

以活力抗旱指数作为玉米萌芽期抗旱性评价指标的初探

首次提出了活力抗旱指数,并以此为指标,在PEG人工模拟水分胁迫的条件下,对18个不同的玉米品种进行抗旱性研究。结果表明:活力抗旱指数和常用的萌发抗旱指数有很高的相关性,且能更好的反映不同品种幼苗水分胁迫下的差别,可以作为玉米萌发阶段抗旱性鉴定的筛选方法。     

外源ABA对干旱胁迫下玉米叶片光合能力及气孔开度的影响

为探究旱胁迫下外源ABA对玉米品种叶片光合作用以及气孔开度的影响情况，以玉米品种‘郑单988’为研究对象，采用PEG、ABA、ABA+PEG不同处理对不同时间节点下玉米苗期叶片光合作用、气孔张开程度和叶绿素含量变化进行研究。发现不同处理下3 个时间节点光合速率、蒸腾速率、气孔导度和叶绿素含量均低于对照，而气孔闭合数目均高于对照；ABA+PEG处理的4 个指标均处于PEG和ABA处理之间。说明干旱胁迫下玉米为了维持自身的生长发育，通过关闭气孔减少水分蒸腾；外施ABA可增加干旱胁迫下气孔的关闭数目和叶绿素含量，减少水分流失的同时提高旱胁迫下植株的光合速率，最终提高植株的抗旱能力。     

水分胁迫下玉米杂交种光合抗旱指数与抗旱性评价研究

通过筛选抗旱玉米品种和抗旱评价指标,进而对其进行生理生化研究,最终实现干旱半干旱地区玉米抗旱节水,是研究玉米高产高效的重要课题。采用盆栽试验方法,选用辽宁省近几年最新选育的12个玉米杂交种,在水分胁迫条件下,对苗期、抽雄吐丝期和灌浆期玉米形态和光合生理等性状特征进行了研究和分析,找出了不同时期水分胁迫下光合抗旱指数与产量抗旱指数的相关性,筛选出了抗旱性较强的玉米品种。结果如下：苗期水分胁迫缩短了58％供试品种抽雄至散粉期时间,延长了83％供试品种的ASI,而铁研120在水分胁迫处理后ASI比对照短,且和其他品种相比,该品种苗期叶片叶绿素含量较高。相关分析表明,灌浆期水分胁迫处理,光合抗旱指数与产量均呈正相关关系,其中,蒸腾速率抗旱指数与产量抗旱指数相关性较强。不同水分胁迫时期的产量抗旱等级划分结果显示,铁研120和铁研58综合抗旱性较强,在苗期、抽雄吐丝期和灌浆期受到水分胁迫,在籽粒成熟期均能获得较高产量。     

渗透胁迫对4个玉米品种种子萌发及幼苗生长的影响

用高渗溶液甘露醇模拟干旱胁迫,对三峡库区主要的4个玉米品种进行发芽和幼苗培养试验.结果表明,干旱胁迫下所有玉米品种的发芽率、苗高、根长、根数、苗鲜重、根鲜重、根冠比等性状都比正常水分下有所下降,品种间表现出较大差异.根据各项指标的试验结果,综合评价玉米品种的抗旱性,初步认定抗旱较强品种为红玛瑙.     

不同玉米杂交种及其亲本自交系抗旱性研究

以玉米杂交种及其亲本自交系为试验材料,对不同基因型玉米抗旱性进行了系统研究。结果表明：（1）在花期水分胁迫下,不同基因型玉米都表现出株高、单株叶面积、叶绿素等指标的下降,且下降的幅度不同。同时,水分胁迫下,玉米植物体内的生理代谢发生了明显变化。叶片相对含水量、保水能力显著降低,可溶性糖升高。与抗旱系数关联度密切的有：叶片相对含水量下降率、丙二醛伤害率、株高下降率等。（2）叶片相对含水量、叶水势即离体叶片失水速率与抗旱性关系密切。这些指标既可以反映植株受旱程度,又可以比较不同基因型玉米抗旱能力。（3）在花期水分胁迫下,不同基因型玉米产量都明显下降。抗旱性强的基因型下降的小,抗旱性弱的品种下降的多。可以用抗旱系数和抗旱指数来衡量不同基因型玉米的抗旱性。亲本及F1代间抗旱性在某些性状上有一定相关性。     

碳酸钠胁迫对不同玉米品种苗期生理指标的影响

试验以筑糯2号、贵单8号、金玉819为材料,在4个浓度水平的碳酸钠溶液(0、12.5、25、37.5mmol/L)胁迫下,进行玉米苗期胁迫试验,分别测定株高、生物量、可溶性糖含量、可溶性蛋白含量、叶绿素含量等生理指标,研究不同浓度碳酸钠溶液对3个玉米品种形态生理指标的影响,旨在明确3个玉米品种对碳酸钠胁迫的适应性。结果表明:碳酸钠胁迫使苗期玉米生物量和叶绿素含量下降,而可溶性糖、可溶性蛋白含量在碳酸钠胁迫下先升高后降低,试验范围内,碳酸钠溶液浓度为25mmol/L作为玉米幼苗耐盐碱性筛选的最适浓度;3个玉米品种的耐盐碱能力顺序为:贵单8号金玉819筑糯2号。     

氮、钾、甜菜碱对水分胁迫下夏玉米叶片膜脂过氧化和保护酶活性的影响

采用盆栽试验研究了水分胁迫和适量供水条件下,氮、钾和甜菜碱对2种不同基因型夏玉米陕单9号（抗旱品种）和陕单911（不抗旱品种）各生育期叶片膜脂过氧化和保护酶活性的影响,旨在揭示这些因子通过提高上述酶活性而增强作物抗旱性的生理功能。结果表明,水分胁迫下夏玉米超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性显著降低,不抗旱品种更甚;而丙二醛(MDA)含量有不同程度升高,抗旱品种的MDA含量和变幅小于不抗旱品种。苗期2个品种对水分胁迫响应较弱,SOD、POD、CAT和MDA均较低;拔节和抽雄期响应强烈,酶活性增高。SOD和POD达到最大值的时间比CAT晚,MDA在全生育期中呈现“升—降—升”的变化规律。施用氮、钾肥和甜菜碱能不同程度地提高夏玉米SOD、POD和CAT活性,降低MDA含量,减缓水分胁迫下膜脂过氧化作用。不抗旱品种施用氮肥增强了水分胁迫条件下叶片SOD、POD、CAT活性,降低了MDA含量,氮肥用量的影响有显著差异;抗旱品种施用低氮效果显著,施用高氮则降低了生育前期酶活性,增加了MDA含量,但生育后期氮肥用量的影响间无显著区别。钾肥和甜菜碱对受水分胁迫的夏玉米表现出比氮肥更突出的效果。而对适量供水条件下的夏玉米,氮、钾肥的作用明显下降,甜菜碱的效果甚至消失。说明施用氮、钾肥和甜菜碱对改善水分胁迫下玉米叶片膜脂过氧化作用和提高保护酶活性有重要贡献。     

宁南山区杂交玉米品种耐旱性鉴定分析

对项目区近年来引进推广种植的高产杂交玉米品种进行苗期耐旱性鉴定。通过对不同水分胁迫条件下,部分关键生长发育、生理指标的测定分析,研究玉米苗期耐旱性指标与产量的相关性,以期为旱地玉米品种抗旱性快速方便测定方法提供参考依据。     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

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.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

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.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

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.     

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.     

Evolution under domestication involving disturbance of genic balance

Summary An hypothesis is developed that the rapid change from wild plants into domesticated crops principally involves the selection of alleles with non-functional gene products which leads to reduced control of the highly integrated metabolism and morphogenesis previously accumulated by lengthy natural selection. Such disturbance of the genome produces altered physiological and morphological development which, although deleterious in nature, serves mankind better and has been selected.