氮磷钾肥对青贮玉米产量和品质的影响

为了探讨施肥对青贮玉米原料及青贮饲料的影响,在撒施羊粪的田间,青贮玉米栽培管理时,分别单独施用氮肥（N-150kg/hm ²）、磷肥（P₂O₅-120kg/hm ²）、钾肥（K₂O-150kg/hm ²）,以不施用化肥为对照,经田间测产和取样,并对其青贮发酵后进行分析。结果表明,增施氮肥能极显著提高青贮玉米产量（P<0.01）,Milk2006奶亩指数显著高于单施磷钾肥和对照处理（P<0.05）;增施钾肥显著提高了青贮玉米的产量（P<0.05）。增施氮肥除了提高玉米青贮饲料氨态氮含量外（P<0.05）,玉米青贮饲料的其他发酵品质参数差异不显著。青贮不仅保存了原料的养分,同时降低了硝酸盐含量。     

品种演替和土壤肥力对小麦产量和磷生理效率的影响

以25年来长期定位施肥试验构建不同土壤肥力梯度为平台,研究品种演替过程中籽粒产量和磷效率对土壤肥力的响应。结果表明,各施肥处理,随品种演替小麦籽粒产量呈显著增加趋势,其中郑麦0856的产量最高(8 157. 3kg·hm-2),郑麦7698次之,豫麦13的产量最低(5 915. 39 kg·hm-2);不施肥处理(CK)则下降。无论施肥或不施肥处理,100 kg小麦籽粒对磷素的需求量均随品种的演替呈上升趋势。此外,随品种演替,磷的生理效率呈先增加后降低的趋势,郑麦941 (172. 48 kg·kg-1)的磷生理效率最高,郑麦9023 (145. 79 kg·kg-1)、郑麦7698 (130. 51kg·kg-1)和郑麦0856 (147. 65 kg·kg-1)次之,三者之间差异不明显,豫麦13 (66. 71 kg·kg-1)的磷生理效率最低;同一品种,单施化肥处理(NPK)小麦磷生理效率显著高于其他施肥处理(MNPK、1. 5MNPK和SNPK)(豫麦13除外)。同时,品种演变明显提高了磷农学效率;但在施肥条件下,继续增施肥料和养分投入使豫麦13、郑麦941、郑麦7698和郑麦9023的磷农学效率降低;而郑麦0856的农学效率随着土壤肥力的增加而增加,与籽粒产量协同提升。因此,黄淮海地区小麦品种演替在土壤肥力养分充足时籽粒产量显著提高,磷效率也呈增加的趋势。     

Simulating long-term effect of Hyrcanian forest loss on phosphorus loading at the sub-watershed level

Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler(LCM) combining with the Soil Water Assessment Tool(SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm~2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm~2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality.     

The effect of taurine supplementation to a plant‐based diet for barramundi (Lates calcarifer) with varying methionine content

The effect of variable taurine inclusion (Tau) (1 g/kg DM to 15 g/kg DM) in the diet of juvenile barramundi (Lates calcarifer) on growth and nutrient utilization was investigated at three levels of dietary methionine (Met) supplementation. Diets were fed to juvenile barramundi (starting weight: 26.8 g) twice daily under a restricted pair‐fed regime for a period of 42 days. No significant effect of dietary Tau supply on growth or nutrient utilization was observed at any level of Met inclusion. Numerical variations suggested a positive effect of Tau provision at the mid‐level of supplementation (6–8 g/kg DM). The best‐fit response model (5‐SKM), fitted to the percentage body weight gain data of fish fed diets with an adequate level of Met, suggested a relatively weak pattern of response (R² = 0.183) and predicted a Tau requirement of 5.47 g/kg DM (9.64 g/kg CP) similar to that reported for several other species. It was concluded that taurine appears to be conditionally essential to barramundi, whereby provision in the diet when sulphur amino acid supply is insufficient to meet biosynthetic demands may be beneficial, but that the predicted requirement is likely reasonably accurate for use as a minimum level of inclusion.     

Determination of dietary phosphorus requirement of stinging catfish Heteropneustes fossilis based on feed conversion,growth, vertebrae phosphorus,whole body phosphorus,haematology and antioxidant status

A 12‐week feeding trial was conducted to determine the dietary phosphorus requirement of Heteropneustes fossilis fingerlings (7.7 ± 0.04 g). Fish were fed casein–gelatine‐based purified diets in triplicate groups near satiation with seven different levels of dietary phosphorus (3.2, 5.2, 7.2, 9.2, 11.2, 13.2 and 15.2 g/kg dry diet). All diets were formulated to be isoproteic (400 g/kg) and isoenergetic (17.89 kJ/g). Highest absolute weight gain (68.38 g/fish), best feed conversion ratio (1.48), protein retention efficiency (30.74%), protein gain (12.44 g/fish), haemoglobin (11.19 g/dL), RBCs (3.12 x10⁶/mm³), haematocrit (33.44%) and serum phosphate (2.82 mg/L) were found at 9.2 g/kg phosphorus. Hepatic superoxide dismutase and catalase activity were also significantly influenced by the dietary phosphorus levels. Whole body and vertebrae phosphorus concentrations increased significantly as the amount of dietary phosphorus increased from 3.2 to 11.2 g/kg dry diet and then plateaued. More accurate information on dietary phosphorus requirement was obtained by subjecting the AWG, FCR, vertebrae phosphorus and whole body phosphorus concentrations data against various levels of dietary phosphorus to broken‐line analysis, which yielded the requirement in the range of 9.0–11.0 g/kg for optimum growth and mineralization of H. fossilis.     

Availability of minerals in rendered meat and bone meal for Nile tilapia: Preliminary observations

A digestibility trial was conducted with 180 Nile tilapia (32.65 ± 4.52 g) fed a reference diet containing 350 g/kg crude protein and 4,500 kcal/kg gross energy. Five different meat and bone meals (MBMs) were evaluated. The test diets compound by 70% of reference diet and 30% of each MBM were elaborated and classified according to ash content: MBM‐430, MBM‐400, MBM‐370, MBM‐340 and MBM‐310. The apparent availability coefficient (AAC) of minerals and the apparent digestibility coefficient (ADC) of dry matter (DM) were subjected to one‐way analysis of variance (p < .05). Differences among ADC and AAC were determined by Tukey's multiple range test (p < .05). When appropriate, a polynomial regression analysis was performed. Linear correlation analyses between MBM chemical composition and the AAC and ADC were performed (p < .01). Higher values of ADC_DM, AAC_Ca and AAC_P were observed in MBM‐310, while low values were observed in MBM‐430. Quadratic effects of ash, P and Ca contents on AAC_Ca, AAC_P and ADC_DM were observed. The AAC_Ca, AAC_P and ADC_DM indicated a negative correlation with ash, P and Ca contents. MBM‐310 exhibited the highest mineral AAC, which could be used as a mineral source for Nile tilapia.     

Dietary available phosphorus requirement for juvenile gibel carp (Carassius auratus gibelio var. CASIII)

A 57‐day growth experiment was conducted with juvenile gibel carp (13.48 ± 0.10 g) in a flow‐through system to study the effect of dietary phosphorus on growth performance, body composition, nutrition utilization, phosphorus loading and enzymes activities. Seven semipurifed diets were formulated to contain 0.07 (the basal), 2.27, 5.32, 8.10, 12.06, 15.24 and 19.48 g available phosphorus/kg diet. The results showed that specific growth rate, body length and feed efficiency significantly increased in the fish fed diets containing 0.07 to 15.24 g available P/kg diet (p < .05). Ash and P content increased in fish fed diets containing 0.07–12.06 P g/kg (p < .05) and then levelled off, while moisture, crude protein and lipid had no significant difference (p > .05). The protein retention efficiency increased in the fish fed with diets 0.07–5.32 g/kg P (p < .05) and then reached a plateau. The P content in faeces was higher in fish fed diets containing 15.24 and 19.48 g available P/kg. Total P concentration in tank water increased in fish fed 0.07–12.06 g available P per kg diet (p < .05). The plasma P was higher in the fish fed with 15.24 g available P/kg diet (p < .05), triglycerides was lower in the fish fed diet containing 15.24 and 19.48 g available P/kg (p < .05), no significant differences were observed in plasma Ca, plasma glucose and calcitonin (p > .05). Based on SGR, whole body P content and FE, dietary available P requirement for juvenile gibel carp were 13.37, 13.97 g/kg and 15.06 respectively.     

Soleris微生物实时光电法与平板计数法测定生乳中菌落总数的比较研究

建立Soleris微生物实时光电检测法检测生乳中菌落总数的快速测定方法,并将该方法与国标的平板计数法进行比较。结果表明：Soleris法检测生乳中菌落总数的标准曲线为y=－0.651 5x＋8.263 9（y为菌落总数（lg（CFU/mL））,x为胶体栓变色时间（h））,相关系数R2=－0.939 6,表明标准曲线相关性良好;重复性实验结果的相对标准偏差均小于5%;Soleris法与平板计数法测定结果的比较表明,2 种方法之间没有显著性差异（P＞0.05）。在本研究的实验条件下,Soleris法检测生乳中     

水稻品种的耐低磷性及其农艺生理性状

【目的】 本研究旨在探明水稻耐低磷性的评价指标和耐低磷品种的农艺生理特征。【方法】以11个江苏省近70年来的代表性粳稻品种作为材料,进行水培种植,设置低磷(标准营养液中磷浓度的1/20)处理,以正常磷浓度(国际水稻研究所标准营养液配方)为对照。【结果】 耐低磷指数(低磷产量×耐低磷系数/所有供试品种低磷处理的平均产量)、干物质指数(低磷干物质量/对照干物质量)与耐低磷系数(低磷产量/对照产量)及低磷处理下的产量呈显著或极显著正相关。将耐低磷指数和干物质指数作为评价水稻品种耐低磷性的指标。根据两指标值的大小将供试品种分成3类：强耐低磷品种,耐低磷指数和干物质指数均≥1;中耐低磷品种,耐低磷指数和干物质指数均>0.6, 耐低磷指数或干物质指数<1;弱耐低磷品种或低磷敏感型品种,耐低磷指数或干物质指数≤0.6。与弱耐低磷品种相比,强耐低磷品种在低磷处理下具有根量大、根系活力强,分蘖早期分蘖数多,总叶面积指数(LAI)和高效LAI大、有效LAI比例高,库容量大,抽穗期茎鞘中糖积累量多,抽穗至成熟期物质生产能力强等特征。与对照相比,低磷处理增加了磷素产谷利用率(稻谷产量/磷吸收量)和磷收获指数(籽粒中磷/成熟期植株中总吸收的磷)。在低磷下的磷素产谷利用率,强耐低磷品种高于弱耐低磷品种。【结论】 耐低磷指数和干物质指数可以作为耐低磷品种的筛选指标;在低磷处理下,根量大、分蘖早期分蘖数多、库容量大、抽穗至成熟期物质生产能力强是耐低磷性强和磷利用效率高水稻品种的重要农艺生理特征。