甜樱桃芽酚类物质含量及相关酶活性变化与自然休眠的关系

 以7年生甜樱桃‘红灯’和‘早红宝石’为试材, 研究了酚类物质含量及相关酶活性在自然休眠期间的动态变化, 探讨了温度对酚类物质含量的影响。结果表明, 甜樱桃芽酚类物质在自然休眠期间持续缓慢增加, 随休眠的结束, 含量急剧下降, 不同品种之间有差异, 自然休眠结束后总酚含量降至最低。花芽中的酚类物质含量略高于叶芽, 多酚氧化酶( PPO) 、苯丙氨酸解氨酶( PAL) 活性差别不大; 不同需冷量的品种之间差异明显。芽中PAL活性与总酚含量的变化趋势呈正相关。而PPO活性在自然休眠期间逐渐升高。低温(5℃) 促进酚类物质的积累, 中期使其提前达到高峰并进入下降阶段, 后期加速其降低;高温(20℃) 效果相反, 变温(5℃/20℃) 效果不明显。     

梨果实发育过程中石细胞团及几种相关酶活性变化的研究

以梨品种西子绿、菊水及砀山酥梨为试材,对不同发育时期梨果实石细胞团的密度、大小及几种相关酶的活性变化进行了研究。结果表明石细胞团的分布密度在幼果期较高,以后随着果实的发育和膨大,密度逐渐减小,接近成熟前1个月左右基本稳定;石细胞团的直径随果实的生长而逐渐变大;苯丙氨酸解氨酶在果实发育初期表现出较高的活性,随着果实的生长逐渐降低,花后75d后保持低水平不变;过氧化物酶活性高峰出现稍迟于苯丙氨酸解氨酶,高峰后呈现出下降的趋势;多酚氧化酶活性波动较大,总的变化趋势逐渐下降。品种间苯丙氨酸解氨酶、过氧化物酶活性与石细胞团的形成之间表现为正相关。     

Identification of organic acid-related genes and their expression profiles in two pear (Pyrus pyrifolia) cultivars with difference in predominant acid type at fruit ripening stage

‘Yandangxueli’ is a pear cultivar with predominant citric acid in the ripe fruit, different from most of pear cultivars such as ‘Gengtouqing’ in which malic acid is the predominant acid type. It was found that ‘Yandangxueli’ accumulated citric acid for three times against that in ‘Gengtouqing’ at fruit ripening stage. To investigate the mechanism of citric acid accumulation in ‘Yandangxueli’, organic acids content, gene expression and enzyme activity were studied in both cultivars. Five genes, Pp:mtCs, Pp:cyAco, Pp:cyIdh, Pp:mtMdh and Pp:cyMe which encoded citric synthase (CS), cytosolic aconitase (cyACO), NADP-dependent isocitrate dehydrogenase (NADP-IDH), NAD-dependent malate dehydrogenase (NAD-MDH) and NADP-dependent malic enzyme (NADP-ME) respectively, were identified from pear fruit. Their expression profiles and the corresponding enzyme activities were determined throughout fruit development in both cultivars. Results from these enzymes indicated that there were no strict relationship between gene expression, enzyme activity and citric acid accumulation. Expression analysis for two Py:vVAtp genes encoding vacuolar H⁺-ATPase A subunit and one Py:vVpp gene encoding Vacuolar H⁺-pyrophosphatase showed that they were all with up-regulated expression at the later development stage of ‘Yandangxueli’ but with down-regulated expression in ‘Gengtouqing’. Therefore, it is concluded that the different ability in citric acid transportation and storage might be involved in the high citric acid content in ‘Yandangxueli’.     

双免耕覆盖对旱地土壤微生物、酶活性和冬小麦干物质转运的影响

为了解双免耕覆盖下旱地土壤微生物数量、土壤酶活性及冬小麦干物质转运特征，研究了双免耕覆盖下麦田土壤中细菌、真菌、放线菌的数量、土壤蛋白酶和脲酶的活性、冬小麦花前和花后干物质向籽粒的转运量与传统耕作（对照）的差异。结果表明，与对照相比，双免耕覆盖下土壤中微生物的数量和酶活性在冬小麦不同生育时期和不同土层均显著（P<0.05）或极显著（P<0.01）高于对照；在0～60 cm土壤中，双免耕覆盖下微生物总量平均较对照高68.2%，差异达极显著水平；土壤中蛋白酶和脲酶活性平均较对照高 27.3%和32.7%。双免耕覆盖下冬小麦花后干物质积累量对籽粒产量的贡献率为44.2%，较对照增加了 61.7%；产量较对照提高18.4%，二者差异达极显著水平。     

The Humus Content and Soil Biological Properties as a Function of Organic and Mineral Fertilization

There is a growing recognition for the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land users in promoting sustainability of agro-ecosystems. Three soil enzymes (dehydrogenase, phosphatase and invertase) microbial biomass as biological variables and soil organic matter content (SOM) were investigated relative to fertilization and soil fertility (estimated by crop yield) at a long-term fertilization trial (Keszthely, Hungary). 0-34.7-69.4-104.1t farmyard manure (FYM) ha m 1 5 yr m 1 and the corresponding amount of mineral fertilizers (NPK) were applied in two different crop rotation systems. There were four straw and/or stalk incorporating treatments in the second crop rotation 'B'. Enzyme activities, microbial biomass and the amount of SOM were generally higher in the fertilized soils than in the unfertilized soils. The type of amendments (mineral, FYM or mixed) had significant effects only on the amount of SOM. The correlations among the biological variables and the crop yield were generally low (r < 0.250. The differences in field management resulted only in the invertase activity.     

Effect op foliar sprays of sulphuric acid with and without elemental sulphur in the prevention of chlorosis In Peanut (Arachis hypogaea. L.)

Abstract

A field experiment was conducted on an alkaline calcareous soil of Agronomy farm of the College of Agriculture, University of Udaipur to study the effect of sulphur on crop yield, leaf elemental composition, chlorophyll synthesis and activities of haematin enzymes. Application of elemental sulphur 21 days before planting with and without 0.1 per cent foliar sprays of H₂SO₄. increased crop yield by 137 to 197 per cent. Application of all these treatnents had no effect on nitrogen, phosphorus and potassium content of leaves but sulphur content was signficantly increased. Iron content of green leaves was decreased significantly 4 to 5 times together with an increase in the activity of catalase and peroxidase enzymes. Chlorosis in these soils appears to be on account of a reduced physiological availability of iron after absorption.     

Effect of cereal type and exogenous enzyme supplementation in pig diets on odour and ammonia emissions

A 2 × 2 factorial experiment was conducted to investigate the interaction between cereal type (wheat vs. barley) and exogenous enzyme supplementation (with or without) on odour concentration and ammonia emissions in grower–finisher pigs. The enzyme supplement used contained Endo-1, 3 (4)-β-glucanase (EC 3.2.1.6) and Endo-1, 4-β-xylanase (E.C 3.2.1.8). The diets were formulated to contain similar levels of digestible energy and lysine. The experimental treatments were as follows: (1) wheat-based diet, (2) wheat-based diet containing a β-glucanase and β-xylanase mixed enzyme supplement, (3) barley-based diet and (4) barley-based diet containing a β-glucanase and β-xylanase mixed enzyme supplement. The diets were offered to the pigs for 4 weeks and this was repeated 4 times (n = 4). Odour and ammonia emissions were measured on days 9, 11, 14, 16, 21 and 23 of each experimental period. Odour samples were collected in 20-litre Nalophan bags and analysed for odour concentration using an ECOMA Yes/No Olfactometer. Ammonia concentrations were measured using Dräger tubes. There was a cereal × enzyme interaction in odour emission rates (P < 0.05) and in ammonia emissions (P < 0.01). The addition of an enzyme supplement increased odour emissions and had no effect on ammonia emissions in the barley-based diet. The enzyme supplementation had no effect on odour but decreased ammonia emissions in the wheat based diet.     

獭兔日粮中添加酶制剂的效果

以９０只生长獭兔为试验动物,研究日粮中添加酸性蛋白酶（Ｐ）和纤维素酶（Ｃ）对日增重、屠宰性能、产品品质的影响,并对经济效益进行分析。结果表明：日粮中添加０．７５％和１．５％的纤维素酶后日增重分别比对照组提高１６．８８％（Ｐ＜０．０５）和２０．５５％（Ｐ＜０．０１）;添加０．７５％Ｐ＋０．７５％Ｃ和０．７５％Ｐ＋１．５％Ｃ后日增重分别比对照组提高１７．６２％（Ｐ＜０．０５）和２２．８２％（Ｐ＜０．０１）;各试验组间无显著差异（Ｐ＞０．０５）;单独添加纤维素酶和同时添加两种酶制剂,对屠宰性能、产品质量无明显影响（Ｐ０．０５）;经济效益以添加０．７５％Ｐ＋１．５％Ｃ为最好,每千克增重较对照组降低成本１．６８元。     

Improvement of quality and shelf-life of strawberries with edible coatings enriched with chitosan

Strawberry fruit have a very short shelf-life and senescent period due to their high degree of perishability and infection caused by several pathogens that can rapidly reduce fruit quality. The aim of this study was to determine the efficacy of carboxymethyl cellulose (CMC), hydroxypropylmethyl cellulose (HPMC) and composites with chitosan (CH) coatings on the shelf-life and overall quality of strawberry fruit. Strawberry fruit dipped for 2 min in solutions of CMC (1%), HPMC (1%), CMC (1%) + CH (1%) and HPMC (1%) + CH (1%) were stored at 11 ± 1 °C, 70–75% RH, while the uncoated fruit served as controls. Fruit coated with edible coatings showed significant delays in the change of weight loss, decay percentage, titratable acidity (TA), pH, total soluble solids (TSS) and ascorbic acid content as compared to uncoated control fruit. In addition, the edible coatings had a positive effect on maintaining higher concentrations of total phenolics and total anthocyanins, which decreased in control fruit due to over-ripening and senescence processes. Compared to the controls, all the coatings had positive effects on the inhibition of cell wall degrading enzymes and among all the tested coatings, CMC + CH and HPMC + CH was superior in inhibiting enzyme activity. These findings suggest that the use of CMC 1% + CH 1% and HPMC 1% + CH 1% coatings are useful for extending the shelf-life and maintaing quality of strawberry fruit.     

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.