Effect of allele combinations at Ppd-1 loci on durum wheat grain filling at contrasting latitudes

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty-five spring durum genotypes carrying all known allele variants at Ppd-1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd-B1a) and the latest (Ppd-A1b/Ppd-B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn-sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring-sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd-B1a and GS105/Ppd-B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.     

不同采收期对余甘果实品质和耐贮性的影响

以福建余甘主栽品种‘粉甘’果实为材料，研究不同采收期对余甘果实品质和耐贮性的影响。结果表明：随着采收期的延迟和果实成熟度的提高，余甘果皮颜色由青绿色逐渐变成黄绿色，果核颜色由深绿色变成棕褐色，果实重量和大小逐渐增加，果实可食率和营养品质提高。可用果实重量和大小、果形指数、果实可溶性固形物、可滴定酸、维生素C含量、果实可食率作为确定余甘果实采收成熟度的参数。同时，不同采收期对余甘果实的耐贮性影响不同，盛花期后179 d采收的果实耐贮性最好，在常温25±1℃下贮藏16 d后，好果率为91%，失重率为3.51%。     

Some Agronomic Strategies for Organic Quinoa (Chenopodium quinoa Willd.)

Quinoa is a potential new seed crop for protein feed and human consumption in Europe, with tolerance to a range of abiotic stresses. For this purpose the study was planned to analyse the effect of important agronomic strategies like nitrogen level, N application strategy, row spacing and harvest time on yield and quality of quinoa. The experiments took place in the field of the experimental station of the Faculty of Science, University of Copenhagen. Three levels of organic nitrogen from slurry was used (60, 120 and 180 kg N ha^?1), supplied either all at once at sowing, or split between sowing and beginning of the reproductive phase. The effect of row spacing and harvest time was studied by harvesting seeds at seed maturity, which occurred 2–3 weeks prior to the mechanical harvest by threshing, and a couple of months after. Yield increased significantly (P ≤ 0.05) with an application up to 180 kg N ha^?1, reaching 2200 kg ha^?1. Increasing N also caused a significantly increased seed weight (up to 3.3 mg) and protein content (up to 17 %). N level did not affect number and amount of weeds. Split application with part of the N applied at bud formation did not have a significant effect on yield. Delayed harvest had a negative influence on seed weight, whereas protein content was stable after harvesting even a month after seed maturity. A late harvest significantly reduced seed germination, being reduced by 50 % after a 2‐month delay. A conclusion from this study is that both yield and protein content of seed can be manipulated by N level and application strategy. Harvest time is important for securing a high seed quality measured as seed germination, seed weight and protein content. A fast germination of quinoa is an important characteristic demonstrating that the crop has good possibilities for being well‐established in the field when free from weeds at the time of sowing. The choice of row spacing is important and depends on weed control method. Weed control strategy should be developed based on modern precision tools.     

Why viewing nature is more fascinating and restorative than viewing buildings: A closer look at perceived complexity

The present paper addresses the question which visual features trigger people’s often more positive affective responses to natural compared to built scenes. Building on notions about visual complexity and fractal geometry, we propose that perceived complexity of magnified scene parts can predict the greater fascinating and restorative qualities of natural versus built scenes. This prediction was tested in an experiment in which 40 participants viewed and rated 40 images of unspectacular natural and built scenes in their original size, and at 400% and 1600% magnification levels. Results showed that the original, unmagnified natural scenes were viewed longer and rated more restorative than built scenes, and that these differences were statistically mediated by the greater perceived complexity of magnified parts of natural scenes. These findings fit with the idea that fractal-like, recursive complexity is an important visual cue underlying the restorative potential of natural and built environments.     

深松整地作业技术要点

根据康平县在实施深松整地作业中遇到的实际问题,介绍深松机具的选择原则、作业质量标准、作业时间确定方法,以及作业技术要点和注意事项,为提高全县深松整地作业质量提供参考。     

减少底肥施用量增加叶面施肥次数对玉米产量的影响

该试验目的是研究降低底肥施用量但是增加叶面肥施用次数方面对玉米产量的变化规律，旨在找出最经济的施肥方式以达到在保护环境的基础上提高经济效益的目的。试验表明，玉米产量随着底肥施用量的增加而提高，并且叶面肥喷施次数越多产量越高，每喷一次，可增加产量258~592.5 kg/hm2，增产幅度2.3%~5.6%。     

‘金艳’猕猴桃果实生长规律及不同采收期对其品质的影响

以‘金艳’猕猴桃为材料,研究其果实生长动态规律及不同采收期(谢花后153 d、168 d、183 d和198 d)(Ⅰ、Ⅱ、Ⅲ、Ⅳ)的软果品质。结果表明：金艳猕猴桃在凉山州西昌市一般4月中旬进入盛花期；在生育期内,果实尺寸(纵、横径)呈前期逐渐增大,后期趋于平稳的变化,谢花后59 d内为果实快速膨大期,谢花后101 d进入生长缓滞期；随采收期延迟,果实软熟时可溶性固形物、干物质和糖酸比呈逐渐升高的趋势；早期采收(Ⅰ、Ⅱ)果实软熟时可溶性固形物、干物质、糖酸比和总氨基酸偏低,淀粉和粗纤维较高；晚期采收(Ⅲ、Ⅳ期)果实软熟时可溶性固形物、干物质、糖酸比较高,淀粉和粗纤维较低,风味更浓,口感更佳；Ⅳ期维生素C和总氨基酸含量最高,但采收较晚不利于当年鲜果销售；若作为鲜果,其最佳采收期为Ⅲ期,Ⅱ期和Ⅳ期可作为备选采收期；作为保健品加工原料,最佳采收期为Ⅳ期。     

施氮时期对葡萄叶片光合生理及内源激素水平的影响

以10 a生酿酒葡萄‘蛇龙珠’为试验材料，运用水肥一体化滴灌的方式分别在萌芽期（S1）、新梢旺长期（S2）、开花期（S3）、果实第一次膨大期（S4）和副梢生长旺期（S5）一次性施入300 kg·hm^-2尿素，对照为整个生育期均不施氮肥（CK），分别于花后50 d（DAF50）、花后85 d（DAF85）和花后120 d（DAF120）进行光合特性指标的测定，并采样分析氮肥施用时期对葡萄叶片光合生理及内源激素水平的影响。结果表明：各生育期施氮均能增加叶片净光合速率（Pn）及PSⅡ最大光化学效率（Fv/Fm），在花前施氮肥叶片Pn和Fv/Fm增加最为显著，最高分别达到18.22 μmol·m^-2·s^-1和0.854。S1、S2和S3处理显著增大了不同生育期叶片气孔导度（Gs）和蒸腾速率（Tr），且S2处理在DAF85时最显著，Gs和Tr分别比CK高18.5%和10.8%；S3、S4和S5处理显著降低了叶片的胞间CO₂浓度（Ci）和非光化学淬灭系数（NPQ），S1处理叶片Ci与CK之间无显著差异。果实第一次膨大期之前施入氮肥能够显著增大各生育期叶片的PSⅡ电子传递量子效率（ФPSⅡ）和光化学淬灭系数（qP），最高分别达到0.889和0.959。可见，不同时期施氮肥，通过改变光合荧光相关参数影响叶片光能的吸收、传递、耗散和分配，从而改善叶片光能利用效率。氮肥的施用时期影响各生育期叶片内源激素的含量，施氮肥均显著提高了DAF85后叶片玉米素（ZT）含量，与CK相比至少提高21.9%；花后施入氮肥叶片中IAA含量在果实采收时保持在34.9 μg·g^-1以上，S4和S2处理GA₃含量最高，分别为7.11 μg·g^-1和6.49 μg·g^-1。因此，氮肥施用时期影响葡萄各生育期不同内源激素的积累。     

多径衰落信道下OFDM系统的符号同步方法研究

由于在正交频分复用（OFDM）的系统中存在符号时间同步误差，为了消除这种误差，提出了工作在多径衰落信道的符号时间频移（STO）估计方法，即基于CP的符号时间偏移估计和基于训练符号的符号时间偏移估计，通过仿真对基于循环序列（CP）估计技术的最大似然法（ML）和基于训练符号的最小均方差异法（Classen）两类性能比较分析，在无载波频移条件下，ML算法精确度更高，当存在载波频移时，Classen算法精确度更高。