Fast measurement of starch content in cold-treated seedlings by infrared spectra

Despite the importance of starch for tree growth, methodological challenges in starch analysis slow down the research on its ecological importance. In this study, a rapid monitoring method was developed for measuring starch content in Pinus taeda L. seedlings after cold treatments. A linear mixed-effects model was used to analyze the effects of cold treatments, seedling tissue types and their interaction on starch content. Mid-infrared (MIR) and near-infrared (NIR) spectra were surveyed, and the results were analyzed using partial least squares regression to determine the starch content. The determination coefficient for calibration and residual predictive deviation were compared between MIR and NIR models to assess the variability of the established models. The results showed that the effects of cold treatments, seedling tissue types and their interaction on starch content were significant. Compared to MIR spectra, NIR spectra is more suitable to estimate starch content in the seedlings. Using NIR spectra, roots provided the most accurate estimates of starch content. The presented guidelines regarding data accuracy as a function of MIR/NIR spectra of samples represent an important methodological reference for starch quantification, which will improve the understanding of the fundamental role of starch in seedlings against environmental forces.     

低温驯化对木薯耐寒性形态、生理特性的影响

用相对耐寒的2个木薯品种华南124和Arg7为材料,设置14℃弱低温驯化后4℃伤害处理、非驯化直接4℃处理和25℃对照,观察和测定了木薯在低温驯化处理下的形态与生理变化。结果表明,该2个品种经低温驯化处理后比非驯化处理,植株形态损伤减轻,恢复正常温度后形态恢复力增强;叶片中的叶绿素含量下降延缓、脯氨酸含量增幅高而丙二醛含量指示的细胞膜破损变小;而在温度恢复过程中叶绿素含量、叶片脯氨酸含量增加均较快。形态与生理指数一致表明,弱低温驯化能够有效提高木薯对低温的适应能力及恢复能力。     

磷脂酶Dβ在拟南芥低温信号中的转导作用

磷脂酶D（PLD）不仅是植物中一类主要的磷脂水解酶,而且是一类重要的跨膜信号转导酶类。PLD的磷脂降解功能和信号转导功能均影响植物的抗冻性。本研究以PLDβ基因被敲除的拟南芥突变体及其野生型植株为材料,进行低温驯化和冻害胁迫处理,并分析其作用途径。结果表明,PLDβ基因介导低温信号转导作用,参与渗透调节途径中脯氨酸的调控和抗氧化系统中过氧化氢酶（CAT）活性的调控,并且与低温信号激素ABA不在同一条信号转导途径。本研究为探索通过调控PLD的活性提高植物抗冻性提供了新的途径,并为深入揭示植物的抗冻机理以及磷脂信号转导机制提供实验支持。     

钙对低温高光锻炼下烤烟幼苗光合的促进效应

以烤烟品种龙江911为材料,研究了喷施CaCl2对烤烟幼苗低温高光锻炼过程中光合和叶绿素荧光特性的影响.结果表明:低温高光锻炼过程中,烤烟幼苗的净光合速率(Pn)、气孔导度(Gs)、最大光化学效率(Fv/Fm)和实际光化学效率(φPSⅡ)均明显低于未锻炼幼苗,说明低温高光锻炼虽然能够增强烤烟幼苗的抗逆性,但却降低了其光...     

Bacteriological studies on the mineralization of organic nitrogen in paddy soils

In this report we studied the effects of mechanical grinding of paddy soils on nitrogen mineralization and bacterial number when soils were incubated under a submerged condition after grinding.

Nitrogen mineralization was increased by grinding soil samples as compared with those without grinding. The value of (Nd-Nu)/Nu, where Nd is the amount of ammonia-nitrogen formed by incubation of disrupted samples and Nu those of the undisrupted soils, was in good correlation with clay/humus ratio.

Although significant difference was not observed between the number of aerobic bacteria with undisrupted and disrupted soil samples, higher anaerobic bacterial numbers were found with disrupted than with undisrupted ones.

A significant correlation was also obtained between the amounts of nitrogen mineralization increased by the grinding of soil and the numbers of anaerobic bacteria.     

结缕草冷处理后可溶性蛋白的变化(简报)

结缕草属(Zoysia Willd.)为重要的暖季型草坪草属之一,很多优良特性^[1]。对结缕草(Z.japonica)的抗寒性研究已有不少。Beard等^[2]对35种暖季型草坪草的抗寒性研究表明,结缕草的抗寒性最强。Dunn^[3]研究表明结缕草属植物耐寒性存在明显的种间差异,而且与抗寒锻炼有关。李亚等^[4]采用改良电导法(EL)对中国54种代表性种质的抗寒性进行了研究。Gerloff^[5]证明低温下苜蓿(Medicago sativaL.)的可溶性蛋白质增多。     

低温驯化及封冻阶段不同冬小麦品种叶绿素荧光参数的比较

为了解小麦品种的抗寒机制,对抗寒品种东农冬麦1号和对照品种济麦22在低温驯化及封冻阶段植株的叶绿素荧光参数进行测定和分析.结果表明,低温驯化阶段对照品种济麦22新叶的最大荧光产量(Fm)、PSⅡ最大量子产量(Fv/Fm)、实际量子产量(yield)、光化学淬灭(qP)显著高于东农冬麦1号,低温驯化结束后济麦22的这些参数迅速降低,显著低于东农冬麦1号新叶相应的值;调查期内东农冬麦1号新叶的初始荧光(Fo)变化稳定,降幅为26.2%,济麦22新叶Fo的降幅为52.8%;两品种老叶的荧光参数值变化趋势接近一致,低温驯化结束后东农冬麦1号老叶的Fm、qN、qP值显著高于济麦22老叶相应的值.在生产上可以利用叶绿素荧光参数对品种抗寒性进行鉴定,鉴定时期为低温驯化期结束、封冻期开始时,鉴定的部位应为植株新叶.     

低温锻炼期间柑桔原生质体SOD和CAT酸活性的变化

３种抗寒性不同的柑桔胚性愈伤组织原生质体经低温锻炼后,原生质体抗寒力得到增强,并在第１２ｄ达到最大。柑桔原生质体ＳＯＤ、ＣＡＴ酶活性变化同步提高,而细胞膜脂过氧化水平随低温锻炼进程逐步下降,至第１２ｄ回升。结果表明：柑桔原生质体ＳＯＤ、ＣＡＴ酶活性与抗寒性正相关,而ＭＤＡ的含量则与抗寒性成负相关,可以利用柑桔原生质体ＳＯＤ、ＣＡＴ酸活性和ＭＤＡ的含量鉴定柑桔原生质体的抗寒性。     

Crown reaction and acclimation to cyclical V-trimming of city trees: An analysis using terrestrial laser scanning

Trimming is an important practice for reducing potential contact between trees and power lines. V-trimming occurs when a tree is located directly under the electrical wires and results in the formation of a bilateral crown, but not much is known about a tree’s reaction and acclimation to such a repeated stress in an urban context.Using Terrestrial Laser Scanning (TLS), we present a study that focuses on documenting (i) short term effect of V-trimming on the tree structure, through the quantification and analysis of the dispersion of trimming induced branch loss and subsequent growth reaction, and, (ii) long term acclimation (i.e. changes in biomass location) of tree structure to repeated unidirectional trimming. A voxelisation method was used to derive space exploration metrics from TLS data based on explored volume quantification and voxels dispersion within the tree crown.Our results show that V-trimming induces a significant decrease in explored crown space volume (12.8% on average) but that this loss is regained by trimmed trees within only 1 year following trimming thanks to a rapid regrowth rate. This was supported by an analysis of radial growth that showed that the growth of trimmed trees was greater than non-trimmed trees although this tendency was not statistically significant. In our study this regrowth was achieved without suckering; instead the regrowth mainly occurred within the crown periphery. We also observed that trimming had a significant influence on the way trees explore space with their crowns. While non-trimmed trees explored space preferentially toward a South direction, trimmed trees explored space in directions perpendicular to the wires (East and West). We also observed that crown biomass was located more in the extreme crown periphery in trimmed trees compared to non-trimmed trees.