Modeling impact of nitrogen carrier and concentration on root substrate pH

We conducted an experiment to quantify the effects on substrate pH from nitrogen (N) carrier and concentration. We used four concentrations of N (3.5–14 mM) and five fractions of ammonium (NH₄⁺) (0–80% NH₄⁺ of total N) that are found in commercially available fertilizers. Fertilizers were applied to fallow 14-cm-diameter pots (1.29 L) filled with a 3 peat:1 perlite (v/v) substrate amended with non-residual powdered calcium carbonate to raise the substrate pH to approximately 6.0. Harvests occurred at 20 and 42 days. Significant effects in the model included main effects of N carrier and N concentration, their squared terms, an interaction effect, and a time × N carrier. The fraction of NH₄⁺ accounted for 45.0% of variation in substrate pH, and N concentration accounted for 1.5% of the total R² of 76.7%. Substrate acidification was likely due to the physiological fertilizer effect and nitrification.     

Effects of abscisic acid and calcium on tomato fruit aroma volatiles

Aroma volatiles are derived from precursors, such as amino acids, fatty acids and carotenoids in tomato fruit. Volatiles enhance the main flavor components in the fruit, particularly sugars. Abscisic acid (ABA) is derived from the carotenoid pathway and there may be an indirect connection to this pathway. Therefore, the purpose of this study was to examine the influence of ABA on tomato fruit volatiles. This study identified five flavor volatile compounds that were consistently present in “Mt. Fresh Plus” tomato fruit tissue. They were 2-methyl furan, (E)-2-hexeanl, 1-hexanol, hexenal, and 6-methyl-5-hepten-2-one. ABA treatments did not have an effect on volatile concentrations in “Mt. Fresh Plus” tomato fruit. Majority of the volatiles identified did not differ between the ABA treated plants and the ABA control plants. However, ABA treatments did significantly decrease (E)-2-hexenal. These results indicated that ABA treatments did not have a major effect on the aroma volatile profile of the fruit.     

模拟酸雨对假俭草叶绿素荧光特性的影响

研究模拟酸雨(pH 2.5、pH 3.0)对假俭草叶绿素荧光特性的影响.结果表明:酸雨6 h胁迫引起假俭草PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/F0)、光化学猝灭系数(qP)、PSⅡ电子传递量子产率(ФPSⅡ)、光合电子传递速率(ETR)和非光化学猝灭系数(NPQ)下降,pH 2.5处理比pH 3.0处理的下降幅度大;酸雨处理停止24 h后, Fv/Fm、Fv/F0、qP、ФPSⅡ、ETR、NPQ回升;酸雨处理停止48 h后,回升至接近对照.研究还表明,利用非损伤的叶绿素荧光技术可快速检测草对环境因子变化的响应.     

植物响应亚适低温的生长发育及分子机制研究进展

近年来，“倒春寒”这一亚适低温灾害频繁发生，严重制约着农林业生产的发展，造成严重的经济损失。为缓解“倒春寒”对作物产生的不利影响，保持农作物正常生长态势，农业生产者通常在灾害发生后采取叶面喷肥等补救措施以降低损失。然而，现有技术手段仍存在费时费力且减害效果不明显等缺陷，亟需开发新的方法来应对这一难题。综述了亚适低温对植物生长发育及其生理生化过程的影响，探讨了外源激素等化学物质添加在减轻冷胁迫方面的作用以及植物响应冷害的分子机制，以期为探索和提高植物对亚适低温的耐受性提供理论参考依据。