长期以来，天然产物为新型农用化学品的发现提供了重要的来源及灵感。在众多的天然产物中，18β-甘草次酸具有广谱的生物活性，更为新药发现提供了重要的活性骨架。为了拓展18β-甘草次酸的农业用途，制备了一系列新型18β-甘草次酸酰胺衍生物，并评价其抗菌性能。以水稻黄单胞菌、柑橘溃疡病菌、猕猴桃溃疡病菌为测试菌株，采用浊度法测试了目标化合物的离体抗菌活性；采用盆栽实验，评估了目标化合物对水稻白叶枯病的防治效果；采用透射电镜对细菌的表型进行了初步验证；借助活性氧实验验证化合物对病原菌活性氧的干扰效果；结合防御酶实验探究化合物对植物防御酶活性的调控性能。通过抗菌活性实验表明，化合物5k对水稻白叶枯病菌(Xoo)具有较好的离体抑菌活性(EC₅₀ = 3.64 mg L^-1)和优异的活体保护活性(54.68%)。进一步通过活性氧实验和表型验证，化合物5k能造成病原菌体内活性氧的过量产生和积累，并进一步破坏病原菌的细胞膜。更值得注意的是,化合物5k能提升包括过氧化氢酶、超氧化物歧化酶、过氧化物酶和苯丙氨酸解氨酶在内的植物防御酶的活性。实验结果表明，制备的18β-甘草次酸酰胺衍生物能通过破坏病原菌的氧化还原平衡并激活植物的防御系统共同发挥其控制植物细菌性病害的潜力。

This study was carried out to evaluate the effects of graded levels of fiber from rice hull and the caecectomy on metabolizable energy (ME) and amino acid digestibility (AAD) in 42 Wuzong geese (21 intact and 21 caecectomized). The experiment was a 3×2 factorial randomized design with 3 fiber levels and 2 treatments of geese (caecectomized and intact). Each of the 3 diets was tube-fed (60 g) to 7 caecectomized and 7 intact adult Wuzong geese that had been fasted for 24 h. Excreta were collected for the next 48 h. The same geese were also fasted for estimation of endogenous losses of amino acids (AA) and energy after short period recovery. AA content and metabolizable energy value were determined in the excreta. In general, significant effects were found for fiber levels on apparent digestibility of Thr, Leu, Pro, Glu,Val, Ala and total AA (P<0.05). Apparent metabolizable energy (AME) and true metabolizable energy (TME) were both significantly influenced by increased fiber levels (P<0.01). Compared with caecectomized geese, markedly increases of AME and TME were found in intact geese (P<0.01 for AME and P<0.05 for TME), but no difference in the AAD were found between intact and caecectomized geese (P>0.05), except for Lys and Try (P<0.05). These observations suggested that dietary fiber level played an important role in digestibility of AAD and ME. Intact geese should be chosen for the nutrient evaluation of feedstuffs in practice, resulting from the significant difference between caecectomized and intact geese.

  The West Liaohe Plain is located in the eastern Inner Mongolia, known as the golden maize belt in China, where maize acreage has continued to rise in recent years. Water is the main limiting factor for maize production in the region, therefore, this study calculated the effect of maize sowing area changes on agricultural water consumption in the West Liaohe Plain in 2000, 2005 and 2010, based on remote sensing and meteorological data. Maize remote sensing classification was constructed based on moderate-resolution imaging spectroradiometer, normalized difference vegatation index (MODIS NDVI) data. Then the maize sown area and water requirement and irrigation water resources were investigated. Finally, the effect of the maize sowing area changes on agricultural water consumption in the West Liaohe Plain was systematically analyzed in 2000, 2005, and 2010. The results showed that maize sown areas rose from 2000 to 2010 and were concentrated in the center of the West Liaohe Plain. Average per unit maize water deficit amount also increased in an uneven distribution, increasing from the south, east and north to the center and west of the West Liaohe Plain. The per unit area maize water deficit increased from 2000 to 2010, and reached 266 mm in 2000, 272 mm in 2005 and 273 mm in 2010, respectively. And the study concluded that water deficit during the whole growth period of maize in the West Liaohe Plain was defined by a single peak curve. The maize water requirements increased with maize sowing area changes from 2000 to 2010, and the maize water requirements increased from 0.89 billion m³ in 2000 to 1.19 billion m³ in 2005, and 1.21 billion m³ in 2010.  

This study investigated effects of dietary fibre and grit on growth performance, gastrointestinal tract (GIT) development, serum indexes and grit retention of Sichuan white goslings in China. The experiment was a 3×2 factorial design consisting of dietary crude fibre (CF) at 2.0, 4.0 and 6.0% levels by adding grass meal and with or without grit supplementation. A total of 720 1-d-old male goslings were randomly allocated into 36 pens of 20 goslings/pen (n=6 pens/treatment). At 21 d of age, GIT, blood samples and grit in gizzards were collected. Body weight (BW), empty BW (without GIT), average daily gain (ADG) and average daily feed intake (ADFI) were affected by CF levels and the medium (4.0%) had the highest value. Adding grit improved BW, empty BW, ADG and ADFI. CF affected relative weight or length of proventriculus, gizzard and duodenum. Increasing CF levels decreased jejunum villus height and affected caecal crypt depth and villus height to crypt depth ratio. Higher CF levels decreased serum triglyceride. Adding grit increased relative weight of abdominal fat. Grit addition increased grit weight in gizzard and the ratio of grit in 0.45-1 and 1-2 mm while decreasing the ratio of grit <0.45 and 2-3 mm. In conclusion, moderate CF level and grit addition increased performance of goslings without interaction. Dietary CF levels affected the development of upper GIT and serum triglyceride. Grit needed by goslings should be less than 2 mm. Goslings’ gizzard would accumulate grit from feed when other grit could not be acquired.