Enhanced kernel set promoted by synchronous pollination determines a tradeoff between kernel number and kernel weight in temperate maize hybrids

Maize (Zea mays L.) grain yield is strongly related to the number of harvested kernels, where kernel number can be increased by synchronously pollinating silks rather than allowing them to be progressively pollinated as they naturally appear from the husks. However, there is scarce evidence on how this practice affects kernel weight (KW) and plant grain yield (PGY), and no report exists on its effects when combined with treatments aimed to reduce apical dominance, like male sterility and detasseling. Field experiments were conducted in two growing seasons (Exp₁ and Exp₂) using two hybrids, cropped at contrasting stand densities (3 and 9 plants per m²) and including (i) male-fertile and male-sterile versions, (ii) tasseled and detasseled plants, and (iii) natural (NP) and synchronous pollination (SP; pollen added manually to ears bagged 5 days after initial silking) systems. Tassel growth of sterile and fertile versions was also evaluated in a separate experiment (Exp₃). Detasseling increased the number of ears per plant reaching silking (P < 0.001) of NP plants, but this beneficial effect of reduced apical dominance did not improve kernel number per plant (KNP) or PGY. Similarly, the early arrest of anther growth in male-sterile plants had no clear benefit on KNP. In contrast, KNP was enhanced by synchronous pollination (range between −13% and +71%; average of +15.4% in Exp₁ and +3.9% in Exp₂). However, this pollination system promoted a decreased in KW (range between −30% and +4%; average of −11.8% in Exp₁ and −7.8 in Exp₂) such that the treatment had no effect on PGY (range between −19% and +37%; average of +1% in Exp₁ and −4% in Exp₂). Because plant growth rate around flowering was not different between pollination treatments, assimilate availability per kernel was reduced from ovary fertilization onwards in synchronously pollinated plants when compared to open pollinated plants. This explains the reduced KW when increasing KNP by synchronous pollination. In summary, none of the imposed treatments allowed grain yield to be increased at the plant level.     

核桃种仁粗脂肪和氨基酸含量的差异性分析

以四川西南地区4个核桃类群为试材,对种仁样品进行了粗脂肪、氨基酸成分的测定与比较分析．结果表明:泡核桃粗脂肪含量与其它3个类群存在明显差异,为744．211 mg·g~(-1);不同类群间氨基酸含量差异显著,夹米核桃表现最优,为223．657 mg·g~(-1),而泡核桃仅有132．249 mg·g~(-1);核桃种仁氨基酸种类丰富,其中含有7种人体必需氨基酸,必需氨基酸占氨基酸总量的29．02%,且比例相对稳定,变异系数仅为3．17%;除蛋氨酸外,另外6种必需氨基酸含量及氨基酸总量存在较大变异,均超过16%．     

基于人体脊柱形态的床垫舒适性测试与评价方法探讨

床垫作为睡眠工具,每天与人体密切接触的时间超过8 h,对人体脊柱健康有重要影响.选择适合自身体型特征的床垫有利于保持脊柱形态,提升人体睡眠舒适性.为评价床垫的人体舒适性,利用人体脊柱形态测量仪,通过建立4项评价指标:站卧脊柱形态吻合度、腰背间隙差、臀背倾角差及脊柱曲度差,对5名被试者在8款弹簧床垫上仰卧脊柱形态与站姿脊...     

浅析影响小麦硬度指标测定的诸多因素

介绍影响小麦硬度的因素,从小麦水分、样品数量、小麦不完善粒含量等因素进行分析。     

Suitability of foliar N applied to rainfed maize in permanent beds after 12 crop seasons of granular N application

Abstract

Yield and kernel quality of rainfed maize as affected by N fertilizer has been generally evaluated through the application of granular N sources at high rates. The purpose of this work was to estimate the response of maize yield and quality (kernel hardness—floating index, weight and test weight -, P uptake and protein) to foliar N application and preceding granular N. Data for this report were collected in 2014 and 2015 in a long-term experiment established in 2002 under permanent beds in a split plot arrangement. Main plot treatments were three foliar N rates (0, 4.5 and 9?kg ha^?1) laid out on the top of four preceding granular N rates (0, 20, 40 and 60?kg ha^?1) applied from 2002 to 2013 as subplots. Weather conditions were relatively wetter in 2014 than 2015. In 2014, test weight and floating index improved over that in 2015. Foliar application of 9?kg N ha^?1 enhanced yield and protein. In 2014, yield response to preceding N rates showed an increasing trend whereas in 2015 response was null. Kernel P uptake response to preceding N rates showed a differential reaction among foliar N rates; 9?kg ha^?1 showed the greatest uptake. Kernel floating index was associated to kernel P uptake. Apparently, this relationship has not been previously reported. Results suggests that the application of 9?kg N ha^?1 to foliage of rainfed maize grown in permanent beds has the potential to substitute the traditional fertilization practice of granular N sources.     

不同加工过程对糖水橘子罐头橘瓣硬度的影响研究

以糖水橘子罐头的橘瓣为研究对象,研究了加工过程中的工艺条件对糖水橘子罐头中橘瓣硬度的影响。采用质构仪对不同工艺条件下的糖水橘子罐头的橘瓣进行测定。结果表明,酸碱处理、杀菌条件、灌汤条件和冷却温度对糖水橘子罐头中橘瓣的硬度有影响。     

培矮64S系列组合制种稻粒黑粉病防控技术研究

研究了肥水管理、“九二０”施用时期与用量、轻度割叶对两系杂交水稻培矮６４Ｓ系列组合制种稻粒黑粉病发生的影响，提出降低氮肥用量、及早晒田控制无效分蘖，在见穗蔸率３％～５％喷施“九二０”，适当增加其用量以及在喷完后轻度割叶等措施，能有效降低稻粒黑粉病的发生率。     

求解中立型常延迟微分方程再生核数值方法

在再生核空间Ｗ＾２ ２（０）中，给出在动力系统等领域广泛应用的中立型二阶常延迟微分方程组数形式的解析解表达式，当解析解级数截断时得到近似解，并分析了此近似解的特点。     

PA序列下非参数回归函数估计的相合性

设{εi,i≥1}为PA序列，Eεi=0，supE（ε^2j）〈∞，对某个r〉2及占〉δ，supE｜εj｜^r＋δ〈∞，u（n）=O（n^（r-2）（r＋δ）/2δ，在PA序列误差下，讨论了非参数回归函数加权核估计的相合性．     

Hardness distribution on wood surface

For better understanding wood hardness, we developed a new hand-operated hardness tester that works with Brinell's method. With this tester we investigated the hardness distribution of wood minutely using a 2mm diameter ball tip. The following results were obtained: (1) On preliminary examination with medium-density fiberboard, we found that the value of Brinell's hardness decreased with the increase in the tip ball's diameter but that it was almost constant with the indenting velocity. (2) By using a small diameter tip, the difference of the hardness became clearer between earlywood and latewood. (3) With radial and tangential sections, we obtained hardness distribution patterns similar to those of wood grain. It seems that the hardness distribution reflects the distribution of density on wood surfaces.