Effect of pre-incubation humidity and temperature treatment on the in vitro germination of avocado pollen grains

Optimum in vitro germination of pollen grain of the avocado cultivars Fuerte, Nabal, Ettinger, Bacon and Zutano occurred at 25 °C. However, there were significant differences between cultivars in percentage germination and relative humidity (RH) requirements for optimum pollen grain growth. The most sensitive cultivar to relative humidity was Fuerte, in which the germination of pollen grain rose from 11.4%, at 40% RH, to about 50%, after one hour at 100% RH. The germination% of Nabal pollen grain was already high at 40% RH and was not increased by higher relative humidity. Increased relative humidity also helped to sustain the viability of avocado pollen. At 30 °C and 5% RH the pollen grains of Fuerte quickly lost its ability to germinate, at 40% RH for 1 hour, germination was reduced spectacularly compared to pollen kept in saturated with moisture environment where it was not affected the first 24 hours. The effects of temperature and relative humidity on fruit-set and yield of avocado are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

盐胁迫对海岛棉种子萌发的影响

研究不同浓度盐胁迫对海岛棉种子萌发和幼苗生长的影响,结果表明:两个供试品种新海21号和新海23号均表现为:①低浓度的NaCl(≤25mmol/L)对海岛棉种子发芽抑制作用较小或无影响,而高浓度的NaCl(≥50mmol/L)则表现出强烈的抑制作用;②无论盐浓度高低,都对海岛棉的幼苗生长产生抑制作用,当NaCl≥125mmol/L时,幼苗的根、茎、叶、根冠比和总干重均显著低于对照;③两个供试品种,新海23号较新海21号耐盐。     

Assessment of cytoplasmic effects of cytoplasmic male-sterile lines in upland cotton

Paired A- and B-lines, cytoplasmic male-sterile (CMS)-lines and main-tainer lines, respectively, were crossed with R-lines (restorer) to produce A × R, R × B and B × R hybrids, which were used in 1993 and 1996 to predict the performance of three lypes of CMS cotton lines available in China. A significant difference in yield and yield components was revealed between paired A × R and B × R hybrids. This difference was greatly influenced by both CMS cytoplasm and the interaction between cytoplasm and nuclear genotypes. It is suggested that there are detrimental effects of CMS cytoplasm on yield and yield components. General combining ability of near-isogenic CMS lines was also affected by this negative effect. The detrimental effect was closely related to an increased number of immature seeds per boll, which might be caused by partial female sterility associated with CMS cytoplasm. The possibility of developing specific combinations of CMS Upland × Upland restorer hybrids that express enough heterosis for yield to overcome the detrimental effect of the CMS cytoplasm is discussed.     

An assessment of thein vitro germination capacity of pollen grains of five tea hybrid rose cultivars

Summary Germination trials of pollen grains of the tea hybrid rose cultivars: Ferry Porche, Bronze Masterpiece, Queen Elizabeth, John F. Kennedy and Lady X, were carried outin vitro, to determine whether these cultivars are suitable as pollen donors in a breeding programme.Pollen grains of all five cultivars germinated poorly in a medium containing sucrose only. Addition of boric acid in the medium improved the germination percentages. The highest germinability was observed in Ferry Porche and Lady X on 15% sucrose+50 ppm boric acid, and 20% sucrose+100 ppm boric acid, respectively. Addition of calcium nitrate in the medium reduced germination percentages in all cultivars.The effect of pH of the medium on pollen grain germinability depended on the cultivar and the composition of the medium. On a medium free of boric acid, the pH values between 5.5 and 7.0 caused a significant increase in the germination percentages of pollen grains of Lady X and Queen Elizabeth. The addition of boric acid decreased the responsiveness of the pollen of all cultivars to the pH changes of the medium.The germination capacity of pollen grains of Lady X and Ferry Porche was not affected by incubation temperatures ranging between 20°C and 30°C.On the basis of the above results Lady X and Ferry Porche are considered the most suitable for pollen donors.     

北疆早熟陆地中长绒棉品种选育及发展探讨

随着人们消费水平的提高和纺织技术的不断发展．国际国内对中长绒棉的需求量也呈逐年上升的趋势．国际上对中长绒棉的需求量以每年7．3％的速度增长。国内需求量每年为40万～50万t，国际市场的需求量近年来达到400万t以上。市场上中长绒棉的价格要比普通中绒棉的价格每吨高出2000元到3000元。     

盐碱胁迫对海岛棉种子萌发及幼苗根系生长的影响

为明确海岛棉种子萌发及幼苗根系对盐胁迫的响应,并筛选出耐盐能力较高的海岛棉品种。以新疆阿克苏地区主推海岛棉品种新海31号、新海35号、新海43号和新海48号为试材,采用NaCl、Na2SO4以及NaCl、NaHCO3以物质的量1∶1混合分别模拟中性盐混合盐(中性盐)和碱性盐混合盐(碱性盐)两种盐类型,胁迫处理总盐浓度(Na+)为0、120、180、240、300、360 mmol L~(–1),研究了盐胁迫下海岛棉种子萌发和幼苗根系生长参数。结果表明,在两种盐类型下,随着盐浓度的增加,海岛棉种子的萌发参数、生物量、根冠比、盐敏感指数、盐耐受指数、根系长度、根系表面积及根系体积均呈下降趋势;高盐浓度下,海岛棉株高、根系生物量及茎叶生物量与盐浓度呈显著负相关,说明高盐环境抑制了棉种发芽及幼苗的正常生长。120 mmol L~(–1)浓度下,中性盐处理的新海48号的根系总长度比对照无显著增加,其余品种均有显著增加,各品种根系总体积与总表面积均无显著差异,低盐促进了各品种细根(d≤0.5 mm)的伸长及生长,新海43号的中根(0.5d≤2.0 mm)长度比CK增加显著,导致此品种根系的总体积与总表面积有显著增加;碱性盐处理的根系总长度、表面积及体积除新海31号与对照差异不显著外,其余品种均有显著降低。180～240mmolL~(–1)浓度下,中性盐处理的根系总长度、表面积及体积与对照相比除新海43号有显著下降外,各品种均差异不显著;碱性盐处理的各品种均是下降显著,其中新海35号的根系总长度下降幅度比其余品种缓慢。300～360mmolL~(–1)浓度下,两种盐处理的各品种的根系总长度、体积与表面积均急剧下降。碱性盐胁迫比中性盐胁迫下降的趋势更为显著。本试验条件下,海岛棉幼苗正常生长所能承受的盐浓度为240 mmol L~(–1),但碱性盐对于海岛棉幼苗的伤害远大于中性盐,供试品种耐盐碱程度为新海35号新海43号新海31号新海48号。     

影响包衣棉花种子发芽的研究初报

种子发芽率是衡量种子质量最重要的指标之一,是种子分级和论价的重要依据。选择最佳发芽条件做好种子发芽试验,对指导农业生产有重要意义。做好包衣棉花种子发芽试验,总结包衣     

新选育陆地型中长绒棉品系性状分析

通过远缘杂交将棉属野生种蕾蒙德氏棉、松散棉、异常棉的优异基因转育到栽培品种中,经过多年多目标定向选择,选育出3个陆地型中长绒棉品系,其纤维2.5%跨距长度32.35~34.46mm,比强度32.20~40.25cN/tex,马克隆值3.85~4.28,且各品系的长度、比强度、马克隆值三者之间均协调较好,适纺高织纱。产量表现虽不及丰产陆地棉,但其绝对产量已达1050kg/hm~2以上,若能优质优价,则可直接用于生产。     

提高棉种发芽率的方法与途径

优良的棉花种子是棉花增产的第一要素,种子发芽率是决定棉花种子质量的重要指标.为确保种子质量,提高发芽率,必须找出影响种子发芽率的因素,寻求提高种子发芽率的方法与途径.     

Genetic effects and heterosis of within-boll yield components in upland cotton (Gossypium hirsutum L.)

Within-boll yield components are the most basic contributors to lint and seed yield of cotton (Gossypium hirsutum L.), which is a major source of natural fiber and edible oil throughout the world. Little information is available on genetic effects and heterosis of these traits in cotton. Three cotton cultivars and six breeding lines differing in within-boll yield components were used for this study. Parents and their F₁ progeny with reciprocals from a 3×6 factorial mating design were grown at Jiangxi Agricultural University experimental farm in 2008 and 2009. Seven within-boll yield components and two boll bur characters were analyzed under an additive-dominance genetic model with genotype and environment interaction. Additive effects were significant for all traits and dominance effects were significant for all traits except seed mass per seed. Genetic variances for lint mass per seed, SM/S and boll bur weight were primarily additive variances ranging from 39.6 to 58.9 %. Lint mass per boll and seed number per boll variances were primarily due to dominance genetic effects ranging from 36.4 to 48.8 %. Dominance and additive effects were equally important for boll weight, seed mass per boll and boll bur percentage. Additive and additive × environment effects were more important than other effects for lint percentage. A802-1 had the best mean performance and additive effects increasing BW, SM/B, S/B and SM/S, but reduced LP and LM/S. A9-1 and Lu40534 had additive effects associated with increasing LP. The two crosses A9-1×Lu40534 and Tezsh×33B were detected with favorable heterozygous dominant effects and heterosis over best parent for BW, LP, LM/B, SM/B and S/B. Favorable genotypic and phenotypic correlations were identified between within-boll lint yield components (LM/B, LM/S) and within-boll seed yield components (SM/B, S/B, SM/S). These results indicate that simultaneous genetic improvement of multiple within-boll yield components can be expected in breeding populations derived from these cotton cultivars and breeding lines.     

A statistical mixture model for estimating the proportion of unreduced pollen grains in perennial ryegrass (Lolium perenne L.) via the size of pollen grains

Summary The size of pollen grains is commonly used to indicate the ploidy level of pollen grains. In this paper observations of the diameter of pollen grains are evaluated from one diploid accession of perennial ryegrass (Lolium perenne L.), which was expected to produce diploid (unreduced) pollen grains in addition to haploid pollen grains. The considerable overlap of the diameter distributions of haploid and diploid pollen grains severely hampers the accurate estimation of the proportion of diploid pollen grains. To overcome this problem we develop in this paper a statistical normal mixture model and we describe a method to test for the production of diploid pollen grains from a diploid parent, and to estimate the proportion of diploid pollen grains.     

Diallel analysis of root-knot nematode resistance based on galling index in upland cotton

The southern root‐knot nematode (RKN) [Meloidogyne incognita (Kofoid and White) Chitwood) RKN] is one of the most destructive pests in the Cotton Belt of the U.S. Developing and employing resistant cultivars is the most economical and efficient method for RKN management. This greenhouse investigation was conducted to understand the quantitative genetic basis of RKN resistance in the major RKN resistance sources using a nine‐parent diallel analysis based on improved RKN evaluation techniques. The selected genotypes consisted of three ‘Aubrun 623 RNR’ (here RNR = R oot‐knot N ematode R esistance)‐derived resistant lines, one moderately resistant cultivar ‘Acala Nem‐X’, and five susceptible cultivars. Comparison between F₁ and their parents in galling index revealed that the RKN resistance is partially dominant. The general combining ability was more important than the specific combining ability for RKN resistance. The estimates for broad‐sense and narrow‐sense heritabilities on galling index were 0.82 and 0.65, respectively, indicating that RKN resistance in the Auburn and Nem‐X resistance sources is largely controlled by genetic and additive effects. The minimum number of genes for RKN resistance was estimated to be two. Therefore, under reliable and uniform RKN inoculation and infestation conditions, single plant selection should be efficient in transferring Auburn RKN resistance into elite genetic backgrounds.     

Two-year study on combining ability and heterotic potential in functional traits under salt stress in upland cotton (Gossypium hirsutum)

Salt tolerance is a physiologically and genetically complex trait controlled by multiple genes. To analyze the genetic basis of salt tolerance we evaluated 18 F₁ along with their nine parents under three salt stress levels i.e. control, 10 dS m⁻¹ and 15 dS m⁻¹ in the summer of 2017 and 2018. Data were recorded for the number of bolls, seed cotton yield, boll weight, Na⁺, K⁺, K⁺/Na⁺ ratio, H₂O₂, SOD, POD, CAT and TSP. Line × tester analysis indicated that the contribution of lines was greater than testers. Except for Na⁺, most of the traits were controlled by non-additive genes. With the rise of salt stress, SCA variances increased and were higher than GCA variances for most of the traits indicating the traits were controlled by a few largely dominant genes. KEHKSHAN, FH-118 and FH-114 were found good general combiner whereas the cross KEHKSHAN × FH-114 was a good specific combiner and also indicated significant better parent heterosis for most traits during two years under salt stress and can be utilized in a breeding programme for salt tolerance.     

地面灌溉条件下中长绒陆地棉的水肥耦合效应

以中长绒陆地棉新陆中9号为材料,在新疆库车县进行了地面灌条件下水肥因素对新路中9号产量影响的田间试验。研究表明,在地面灌条件下水肥对中长绒棉都具有增产效果,单株结铃数与产量呈线性正相关,过多的水肥投入并不有利于棉花增产,合理肥料投入有利于发挥灌溉的增产作用。灌水量、施肥量与产量藕合关系的多元回归方程是为：Y=-1453.04+1.32703I+5.12236F-0.000211I2-0.005032F2-0.000263 I*F。新陆中9号获得最高产量1568kg/hm2时全生育期中合理施肥量和灌水量分别434kg/hm2（其中N 235kg/hm2、P2O5 143kg/hm2、K2O 56kg/hm2）和2879m3/hm2。     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 1. Genotypic and environmental effects on pollen grain germination,pollen tube growth and the frequency of fertilization

Summary A quantitative examination of pollen grain germination and pollen tube growth within the overy wall was made in selected wheat × tetraploid H. bulbosum hybridizations, to investigate the effect of the wheat and the H. bulbosum genotype on these characters. As expected, variation at the known crossability loci had no effect on pollen grain germination. The frequency of pollen tube penetration of the ovary wall was, however, severely reduced when the dominant alleles were present. Pollen tube penetration was nevertheless observed in 3 of the 110 ovaries examined of the non-crossable cultivar Highbury. The H. bulbosum genotype had a much smaller effect on these characters, but significant differences between the clones were observed in the numbers of pollen tubes initially penetrating the ovary wall. Although two H. bulbosum genotypes showed no significant differences in the number of ovaries with pollen tubes at the base of the ovule, significant differences in the frequency of fertilization were observed. The possible cause of this discrepancy is discussed.The frequency of fertilization in crossable wheat × H. bulbosum hybridizations was improved by the application of gibberellic acid within 10 minutes of pollination, and reduced by an increase in the ambient temperature from 20°C to 26°C. Fertilization following the pollination of non-crossable wheat genotypes was not affected by either of these factors.     

Effects of gamma irradiation on in vitro pollen germination of different Cucumis species

Summary Pollen grains of 14 Cucumis accessions were irradiated with 0, 1, 2, 3 or 4 kGy acute gamma rays and germinated in vitro directly afterwards. Pollen germination was significantly reduced by increasing irradiation dose for all species, except C. melo var. agrestis. Pollen tube growth was generally reduced likewise. Pollen of two C. anguria subspecies was most sensitive to irradiation. Sensitivity of the pollen with respect to pollen tube growth in relation to irradiation dose was inversely related to total DNA amount per nucleus. In vitro germination was not related to DNA amount per nucleus. Results show that the examined Cucumis species, especially C. melo var. agrestis, are sufficiently resistant to irradiation to be used as donor species for in vivo egg cell transformation of the cucumber.     

Effects of high temperatures on mature pollen grains in wild and cultivated maize accessions

Summary The effects of high temperature on mature pollen of various maize lines were investigated. Genotypic differences in pollen reaction to high temperature were revealed. Pollen grains resistant to high temperature (35°C, 26°C) were characterized by higher germination capacity and better ability to develop normal pollen tubes. The studies are of interest to evaluate reproductive system tolerance and conduct gamete selection at the mature pollen grain stage in maize.     

不同芽床对花生种子发芽试验结果影响初探

本文以8130花生品种为材料,研究了纸床和砂床对花生种子的发芽、活力影响情况及差异性.结果表明,不同发芽床花生种子的发芽率、活力有差异,砂床明显高于纸床;同时,在砂床中种子的不同放置方式、纸床中纸间和纸上法之间,试验结果也有区别.因此,同一品种,发芽方法不同,发芽结果也有差异.