Influence of decreasing water temperature and shortening of the light phase on macronutrient self-selection by rainbow trout Oncorhynchus mykiss and common carp Cyprinus carpio

SUMMARY: Macronutrient self-selection patterns in rainbow trout and common carp, which were maintained in groups, were examined when both water temperature and duration of light phase gradually decreased. Three semipurified macronutrient diets composed mainly of protein (casein and gelatin; crude protein (CP) = 65%), fat (pollock oil and soybean oil; crude fat (CF) = 38%), or digestible carbohydrate (dextrin and gelatinized starch; crude starch (CS) = 57%) were offered to five groups of trout (20 fish/group, 51 g/fish) and carp (15 fish/group, 36 g/fish) using three self-feeders. A standard diet (ST) containing the three macronutrients at an appropriate ratio (CP = 47%, CF = 14%, CS = 25%) was also offered to three groups each by a single self-feeder. After an initial 3 weeks of experiencing a long photoperiod (14 h light : 10 h dark cycle) and high water temperature (trout, 17°C; carp, 25°C), the light phase and temperature were gradually decreased in the following 3 weeks to 10 h light : 14 h dark, and 8°C for trout and 13°C for carp, and feeding was continued for a further 3 weeks under low temperature and short photoperiod conditions. Growth and protein utilization parameters between the ST diet self-fed groups and macronutrient diet self-selection groups were not different ( P > 0.05) for both trout and carp. Trout preferred the high-protein diet (HP) to the high-fat and the high-carbohydrate diets ( P < 0.05) regardless of the changes in water temperature and photoperiod. Carp also preferred the HP diet ( P < 0.01) under the high temperature and long photoperiod conditions; however, this preference gradually disappeared with lower temperatures and shorter photoperiods. These results suggest that the most appropriate macronutrient ratios in carp diets change with environmental conditions.     

A framework for the study of macronutrient intake in fish

A good understanding of the capabilities of commercially reared fish species to regulate intake of specific macronutrients has potential economic, welfare and environmental benefits. We present a conceptual and experimental framework for studying macronutrient intake in fish. This ‘geometric’ approach addresses the multidimensional and interactive nature of nutrition. It was developed from work on insect herbivores and has successfully been applied to mammals and birds. The various components of the framework are introduced in simple outlines, and key experimental designs are described for assessing whether or not fish specifically regulate their intake of macronutrients, how they balance over-ingesting some nutrients against undereating others when provided with suboptimal diets, and how they regulate growth post-ingestively.     

基于电极阵列的土壤速效养分快速检测系统

从降低检测成本和提高时效性出发,设计了基于电极阵列的土壤速效养分快速检测系统,系统主要包括电极阵列、单片机和信号调理等模块,其中电极阵列为传感单元,主要由pH电极、硝酸根电极、钾离子电极、磷酸盐电极和参比电极组成.性能测定结果表明,系统输入阻抗达到1012Ω数量级,输入电流小于1 pA,响应电位测量范围为-2 000 ～2 000 mV,可与主流离子选择电极实现较好匹配.自主研发的基于电极阵列的土壤速效养分快速检测系统可基本满足土壤对pH值、硝态氮和速效钾的速测要求.     

中国甜菜产质量主要养分限制因子研究

中国甜菜种植主要分布在东北、西北、华北3个生态区,为探明当前甜菜生产上块根产量和含糖量的主要养分限制因子,分别在3个甜菜产区,通过设置缺素处理,进行了2年23个点的田间小区试验。结果表明：在东北区氮磷对产量限制显著(P＜0.05),硼对产量和钾对含糖的限制作用在所有试验区域均有不同程度表现,甜菜产质量主要限制因子的顺序依次为N＞P＞K＞B＞Zn。在西北区氮和硼是产量的最主要限制因子,缺乏后减产效果均达到显著水平(P＜0.05),各元素对产质量的限制依次为N＞B＞P＞K＞Zn。华北区5种元素对甜菜产量的限制作用均达到显著水平(P＜0.05),其中氮的作用最大,其他4种元素的作用接近,锌对含糖的限制作用达到显著水平(P＜0.05),各因子对甜菜产质量的限制依次为N＞Zn＞B＞P＞K。     

Effects of Nitrogen Fertilization and Genotype on Rice Grain Macronutrients and Micronutrients

High nitrogen(N)input features China’s intensive rice production system.To elucidate N and genotype effects on accumulation of macronutrients and micronutrients in grains of japonica rice,and to discuss its significance in rice production,a three-year field experiment involving six japonica rice varieties and seven N treatments were performed.Macronutrients(Ca,Mg,K,and Na)and micronutrients(Cu,Fe,Mn,and Zn)concentrations in brown and milled rice were measured using an atomic absorption spectrophotometer.For macronutrients,no consistently significant effect of N was detected in both brown and milled rice.For micronutrients,N showed significant effect,especially in lowering Zn accumulation in brown and milled rice.In addition,N tended to increase Fe concentration in milled rice.Genotype showed larger effect on distribution of minerals in milled rice than N.The high-yielding variety,Wuyunjing 7,accumulated larger proportion of Mg,K,and Zn in the milled rice as compared with the other five varieties,and could be of value for rice breeding programs aiming at high nutritional quality.The results demonstrated differences in response to N between macronutrients and micronutrients,and are of significance for coping with‘hidden hunger’both in humans and crops through agronomical practices.     

毛竹笋体内氮磷钾含量与氨基酸成分的关系

本试验研究了毛竹笋体氮、磷、钾含量与氨基酸成分的关系。结果表明:冬笋体内大部分游离氨基酸含量与其氮钾含量成显著正相关。大部分水解氨基酸含量,与冬笋P％成显著正相关,与春笋K％成显著负相关,与N％的关系,无论冬笋或春笋都成显著正相关。春笋体内N/K,N/P比值与大部分水解氨基酸成显著或极显著正相关;而在冬笋中,这种关系不很明显。冬春笋这种氮、磷、钾含量及其比例与笋体水解氨基酸含量的关系存在差异的原因被认为是笋体生长阶段不同所引起的一系列生理和生化过程差异。     

螺旋藻室外长期培养及其养分动态

对螺旋藻室外培养和培养液主要养分消耗进行了90天的监测,获得了藻的生长和培养液中No_3~-、P_2O_5、K~+及NaHCO_3的动态规律;发现在室外按少量分批添加的原则维持有效磷(P_2O_5)80mg/L,No_3~-150mg/L,K~+250mg/L的低浓度可以支持螺旋藻的生长。本文还讨论了后期改变培养条件,提高NaHCO_3利用率的途径。     

The influence of phosphorus and calcium application rates on the mineral composition of the perennial legume Macrotyloma axillare

The response of legumes to the supply of either phosphorus (P) or calcium (Ca) alone has been extensively investigated but no prior studies have evaluated their combinations in the perennial legume Macrotyloma axillare (Macrotyloma legume). This study assessed the mineral composition of Macrotyloma legume in response to the combined application of P and Ca in an Ultisol. The experiment was conducted in a greenhouse in Nova Odessa city, São Paulo, Brazil. Five rates of P and Ca, respectively, were combined in a 5² incomplete fractional factorial design. Thus, the treatments consisted of 13 P and Ca combination rates (respectively, in mg dm^?3): 0?0, 0?40, 0?80, 15?20, 15?60, 30?0, 30?40, 30?80, 45?20, 45?60, 60?0, 60?40 and 60?80 arranged in a randomised block design with four replications. Mineral composition was evaluated after two harvests (53 d after sowing and 34 d after the first harvest). During the initial growth of the Macrotyloma legume, P × Ca interactions occurred. The P supply antagonistically influenced the nitrogen content. The excess P supply reduced nitrogen accumulation in the shoots and caused a lack of nitrogen in the leaves. The Ca supply synergistically impacted the magnesium content and caused a ‘Viets effect’ in potassium content.     

Influence of Boron on Sunflower Yield and Nutritional Status

Sunflower has been mentioned in the literature as a plant that requires large amounts of boron (B) to achieve a successful crop. This study aimed at evaluating the influence of sunflower fertilization with boron on the soil nutrient concentration, index leaf, seed yield, fatty acids’ composition of sunflower oil, and oil content. Cultivar M734 was selected for boron fertilization at 0, 3, 6, 9, and 12 kg ha^?1 rates. The maximum economic return was obtained with 3.13 kg ha^?1. Neither oil content nor fatty acid composition was affected by boron. With proper irrigation, the M734 cultivar was able to absorb boron in the 0 ? 40-cm layer, ultimately producing about 3000 kg ha^?1 of seeds in soils with only 0.30 mg kg^?1 of boron. Based on these results, it is suggested that the boron fertilization program be expanded to include the soil strata at 0?20 cm and 20?40 cm.     

Magnesium-fortified phosphate fertilizers improve nutrient uptake and plant growth without reducing phosphorus availability

Magnesium (Mg) deficiency can significantly limit crop yield and quality. Separate application of straight Mg fertilizer is unattractive because of additional labor costs. Meanwhile, bulk blending Mg with other macronutrient fertilizers is also a suboptimal solution because bulk blended fertilizers often yield poor nutrient distributions. One rapid and economical alternative to alleviating Mg deficiency is to co-granulate macronutrient fertilizers with Mg. However, few commercial products have implemented this approach. One of the barriers hindering the production of Mg-fortified phosphorus (P) fertilizers is the assumption that precipitation of P with Mg will reduce P solubility. In this study, four Mg compounds, anhydrous magnesium sulfate (MgSO₄), magnesium oxide (MgO), anhydrous magnesium chloride (MgCl₂), and dolomite (CaMg(CO₃)₂), were co-granulated with mono-ammonium phosphate (MAP), and their granule strength, Mg and P availabilities, and agronomic effectiveness were evaluated. Results showed that there were no significant differences in P solubility between Mg-fortified MAP and MAP treatments. X-ray diffraction (XRD) indicated that the Mg species after co-granulation were boussingaultite (Mg(NH₄)₂(SO₄)₂·6H₂O), schertelite (Mg(NH₄)₂H₂(PO₄)₂·4H₂O), magnesium hydrogen phosphate (Mg(H₂PO₄)₂), and dolomite (CaMg(CO₃)₂). A pot experiment using an acidic soil demonstrated an average 9.6-fold increase in shoot Mg uptake, 3.0-fold increase in shoot P uptake, and 3.2-fold increase in soybean shoot dry matter in Mg-fortified MAP treatments, compared to those in MAP treatment. The current study provides a simple, effective, and low-cost approach for the addition of Mg to macronutrient fertilizers, to minimize Mg deficiency.