High Night Temperatures During the Floral Bud Stage Increase the Abscission of Reproductive Structures in Cotton

Cotton‐producing regions throughout the world often experience high night temperatures (HNTs), affecting flowering and yield in cotton (Gossypium hirsutum). The objective of this study was to quantify the effects of high nighttime temperatures on the physiological and biochemical characteristics of cotton during the floral bud and flowering stages. Growth chamber experiments were conducted in 2011–2012 and treatments included a control (day/night temperature of 32/24 °C) and two HNT treatments (32/29 °C from 8:00 pm to 12:00 am) for 3 weeks from the beginning of each phenological stage, i.e., first floral bud (B1) and first flower (F1). The results indicated that increased night temperatures (NTs) during the floral bud and flowering stages increased the rate of flower production per plant. However, no increase was observed in the final number of reproductive structures because the rate of floral abortion also increased for both treatments compared to the control. Additionally, the increase in night temperature during the floral bud stage reduced the sucrose content in the flower, resulting in decreased pollen viability and premature abortion of reproductive structures while the onset of flowering period was also delayed and lower accumulation of reproductive dry matter was observed. HNTs during the flowering stage reduced the number of seeds per locule and the number of seeds per boll. In general, higher than optimum NTs affected sucrose metabolism of the cotton flower and consequently its pollen viability. As a result the flowering period was delayed and a reduction in reproductive dry matter accumulation was observed due to premature abortion of reproductive structures. Finally, cotton is more sensitive to HNT at floral bud stage and this finding may be important to adjust cotton planting date, management and breeding.     

沙苑子的生理功能评价研究进展

沙苑子是陕西正宗道地的中草药之一。目前,沙苑子良好的保健功能已引起研究人员的注意。沙苑子的化学成分与其药理作用有密切的关系。该研究对国内外沙苑子药理作用的研究工作尤其是与保健相关的功效如沙苑子的毒性评价、对心脑血管系统的影响抗炎作用等进行全面的归纳和总结,同时展望其研究方向。     

二月兰种子生活力与耐盐能力研究

研究了不同贮存年限二月兰种子的生活力,并采用单盐和复盐胁迫,系统研究了二月兰干种子与萌动种子在盐胁迫下的致死率与耐盐机理.结果表明:常温贮存2年的种子与贮存1年的种子发芽率与发芽势均较高,2013年种子生活力虽总体上好于2014年种子,但二者差异不显著.与干种子相比,萌动种子更耐盐胁迫;单盐胁迫下,干种子半致死浓度和临界浓度分别为1.6％和1.8％,萌动种子半致死浓度和临界浓度分别为1.8％和2.0％;复盐胁迫下,干种子羊致死浓度和临界浓度分别为0.4％～0.6％和0.6％～0.8％,萌动种子半致死浓度和临界浓度分别为0.6％～0.8％和0.8％～1.0％.在干种子萌发过程中,随着盐胁迫浓度的增大,萌发高峰期延迟,发芽率下降.游离脯氨酸含量在单盐胁迫中呈持续增大趋势,而在复盐胁迫下则先上升后下降.相对电导率在单盐与复盐胁迫下虽然总体上均呈上升趋势,但出现了不同程度的小高峰.     

超干处理对黄檀种子发芽率及生活力的影响

为了研究黄檀种子超干贮藏的适宜含水量,采用人工老化法研究超干贮藏对黄檀种子发芽率及生活力的影响。通过对含水量为2.4%~12.1%老化黄檀种子的发芽率、发芽势、发芽指数、活力指数以及电导率等指标的检测,结果表明黄檀种子含水量(MC)降至4.5%,能显著提高抗老化劣变的能力。在同等老化处理(50℃,15 d)后,未超干种子(MC=12.1%)完全失去了发芽能力,而超干种子(MC=2.4%~4.5%)的发芽率仍保持在64%以上。电导率测定结果表明,超干种子经回水处理后细胞膜系统的完整性良好。     

Cytology and pollen grain fertility in creeping bentgrass interspecific and intergeneric hybrids

Creeping bentgrass (Agrostis stolonifera L. or A. palustris Huds.) is a highly outcrossing allotetraploid species. It can form hybrids with a number of other Agrostis species and Polypogon genus. However, cytology and pollen grain fertility of the creeping bentgrass interspecific and intergeneric hybrids are not well known. In this research, chromosome pairing behaviors during meiosis I in F₁ and pollen viability of F₁ hybrids, as well as seed set rate and seed germination rate of backcrosses were studied in hybrids between creeping bentgrass, and other bentgrass species and three species of Polypogon genus. Abnormal chromosome pairing, laggard chromosomes, and premature segregation in F₁ hybrids were found. Pollen viability ranged from 1.6 to 48.5% amongst F₁ hybrids, significantly lower than that of the parents (85.5–94.1%). Some hybrids produced pollens of different sizes within the same anther. Seed set following backcrosses using F₁ hybrids as the male parent and creeping bentgrass as the recurrent parent was significantly lower than their parents. The study of chromosome paring behaviors and progeny fecundity are important in utilizing the alien genes to improve bio-stress and abio-stress resistance, and in assessing the potential transgene risks of creeping bentgrass.     

Genetics of the viability of pollen grain produced at low temperatures inLycopersicon Mill.

Summary The different viabilities of pollen produced at low temperatures in intra- and inter-specific crosses of tomato were studied. Cultivars Red Top, Moneymaker, and Marroqui were crossed with cultivar E-15 and these four cultivars were hybridized with lines of the wild speciesL. pimpinellifolium PE-13,L. parviflorum PE-52,L. pennellii PE-47, andL. hirsutum PE-37 and PE-41. A six-generation family of the Moneymaker x PE-47 cross was obtained to carry out a more detailed genetical study of pollen grain viability at low temperatures. Pollen grain viability was evaluated during the winter via acetocarmine staining. When the parents were compared with their F₁, the intra-specific tomato crosses showed dominance to better-quality pollen, theL. esculentum x L. pimpinellifolium inter-specific crosses showed positive heterosis, while the crosses ofL. esculentum with the tolerant speciesL. pennellii andL. hirsutum showed intermediate inheritance. However, in theL. esculentum x L. pennellii family, the dominance and the non-allelic interactions (homozygosis x homozygosis) were the most important factors, so that dominance to better viability at low temperatures appeared to be the general mode of inheritance. Genetical control of pollen grain viability at low temperatures seemed to be polygenetic.     

Effect of D-Genome Chromosome Substitutions on Hybrid Seed Development and Viability in T. turgidum var. durum X S. cereale Crosses

Triticum turgidum var. durum cv. ‘Langdon’ and the set of D-genome disomicsubstitutions in ‘Langdon’, produced at Fargo, U.S.A., were grown in a temperature controlled greenhouse and crossed with diploid spring rye (Secale cereals), to determine the effect of each substitution on 1. the crossability with rye, and 2, the viability of the resulting hybrids kernels. None of the disomicsubstitutions lines, with the possible exception of the 5D (5Bj line, gave an appreciable improvement in hybrid kernel set, -development, and -viability over the control, ‘Langdon’ The post-zygotic barrier to endosperm and embryo development, which operates in crosses between durum wheat and rye, could therefore not be suppressed by any specific chromosome of the D-genome.     

Hybrid Tea-rose pollen. II. Inheritance of pollen viability

Summary Pollen viability was evaluated in about 500 seedlings originating from 31 crosses between nine commercial Hybrid Tea-rose varieties. The data indicated that pollen viability was inherited additively.     

The shriveling of pollinated pistils as an aid to rapid determination of Chrysanthemum pollen viability

Summary Shriveling of pistils observed one day after pollinating the dise florets of Chrysanthemum is normally followed by a good seed set 8 weeks later. When shriveling fails to appear, no seeds will be formed.It is suggested to use the easily visible pistil shriveling as a rapid in vivo test of pollen viability.