盐分胁迫下喷施γ-氨基丁酸对水稻秧苗生长的影响

为探究喷施γ-氨基丁酸（GABA）对不同程度盐分胁迫下水稻秧苗生长的影响，以天津主栽粳稻品种天隆优619为研究对象，在秧苗采用穴盘培育到3叶1心时，分别用0、25、50、75、100 mmol/L NaCl溶液水培，并设置叶面喷施4 mmol/L GABA处理，以叶面喷水作为对照组，调查水稻的生长指标和3种抗氧化酶活性。结果表明，随着盐分胁迫程度的增加，水稻的株高增量、叶面积呈下降趋势，死叶率、根系干鲜比、叶片POD和SOD酶活性呈上升趋势，根系活力和叶片APX酶活性呈先升后降趋势。在相同盐分胁迫下，与不喷施GABA对照相比，喷施GABA处理表现为：株高增量增加1.7%~32.4%，死叶率降低1.6%~23.3%，根干质量减少9.3%~22.0%，根系活力增加1.2%~94.4%，叶片POD、SOD和APX酶活性分别增加5.0%~20.8%、9.8%~17.3%和7.2~64.4%。可见，叶面喷施4 mmol/L GABA能够提高供试水稻的耐盐性，促进同化物优先向地上部分配。     

Effect of antifungal hydroxypropyl methylcellulose-beeswax edible coatings on gray mold development and quality attributes of cold-stored cherry tomato fruit

Edible composite coatings based on hydroxypropyl methylcellulose (HPMC), beeswax (BW), and food preservatives with antifungal properties, were evaluated on cherry tomatoes during cold storage. Food preservatives selected from previous research work included sodium propionate (SP), potassium carbonate (PC), ammonium phosphate (APh) and ammonium carbonate (AC). Cherry tomatoes artificially inoculated with Botrytis cinerea were coated and stored up to 15 d at 5 °C followed by 7 d of shelf-life at 20 °C. All antifungal HPMC-BW coatings significantly reduced gray mold development on inoculated and cold-stored cherry tomatoes, the SP-based coating being the most effective. Analytical and sensory fruit quality was also evaluated after cold storage and shelf-life. The AC-based coating was the most effective to control weight loss and maintain the firmness of coated cherry tomatoes. Respiration rate, firmness, color, sensory flavor, off-flavor, and fruit appearance were not adversely affected by the application of the antifungal coatings. Overall, the application of HPMC-BW edible composite coatings containing AC could be a promising treatment to extend the postharvest life of cherry tomatoes. Further studies should focus on the modification of some physical characteristics of the coatings in order to enhance the general performance and provide higher peel gloss.     

乡村数字化对中国农业韧性的影响机制——基于耦合协调度和中介效应模型的实证

为探究乡村数字化对农业韧性的影响，利用2011—2020年中国30个省(直辖市、自治区)的面板数据(统计数据未含西藏及港澳台地区，下同),采用熵值法测算了中国农业韧性与乡村数字化发展水平。利用耦合协调度模型、中介效应模型分析了二者的协调程度，探究了乡村数字化对农业韧性的作用机制。结果表明：当前我国农业韧性水平与乡村数字化发展水平及二者的耦合协调程度总体呈上升趋势；乡村数字化可通过缩小城乡收入差距、提升农村人力资本水平促进农业韧性提高；乡村数字化在农业韧性水平低的地区提升效应更加明显。     

Changes in spatial distribution of primary production,photosynthetic pigments and phytoplankton species composition during two surveys in the German bight

A grid of 61 stations was sampled twice in the German Bight. At all stations dissolved nutrients (Si, P, N), fluorescence, temperature and salinity were measured along the vertical at surface, 5 m, 10 m, and 10 m intervals till the bottom. At selected stations photosynthetic rates were measured with ¹⁴C method (both surveys) and pigment with a HPLC method (first survey). Phytoplankton species composition was dominated by small diatoms, mainly Leptocylindrus minimus, flagellates, both dinoflagellates and choanoflagellates and near shore blooms of Phaeocystis pouchetii. Primary production and chlorophyll-a showed a linear correlation (r=0.90, n=23). Primary production showed highest rates along the North and East Frisian islands, where phytoplankton was dominated by Phaeocystis and Leptocylindrus. These coastal stations were completely mixed whereas a large part already showed stratification due to salinity and temperature. Thermocline and pycnocline were at about 10 m depth. No differences in oxygen content of surface or bottom waters were observed. Silicate and phophate concentrations were very low whereas nitrogen still showed very high concentrations. Low hypolimnetic oxygen concentrations are only possible when transport of primary produced organic matter is transported to stratified regions later in summer. Rapid growth of blooms was observed within a weeks period. More primary production measurements in the German Bight should be done to allow for budget calculations of oxygen consumption below the thermocline.