Uptake and nutrient balance of nitrogen,sulfur, and boron for optimal canola production in eastern Canada

Balanced plant nutrition is essential to achieve high yields of canola (Brassica napus L.) and get the best economic return from applied fertilizers. A field study was conducted at nine site‐years across eastern Canada to investigate the effects of nitrogen (N), sulfur (S) and boron (B) fertilization on canola nutrient uptake, nutrient balance, and their relationship to canola yields. The factorial experiment consisted of four N rates of 0 (N0), 50 (N50), 100 (N100), and 150 (N150) kg ha^?1, two S rates of 0 (S0) and 20 (S20) kg ha^?1, and three B treatments of 0 (B0), 2 kg ha^?1 at preplant (B2.0P), and 0.5 kg B ha^?1 foliar‐applied at early flowering stage (B0.5F). Each site‐year used the same experimental design and assigned treatments in a randomized complete block design with four replications. Fertilizer S application greatly improved seed yields at six out of nine site‐years, and the highest N use efficiency was in the N150+S20 treatment. Sulfur application generally increased seed S concentration, seed S removal, and plant total S uptake, while B fertilization mainly elevated straw B concentration and content, with minimal effect on seed yields. At the early flowering stage, plant tissue S ranged from 2.2 to 6.6 mg S g^?1, but the N : S ratio was over or close to the critical value of 12 in the N150+S0 combination at five site‐years. On average across nine site‐years, canola reached a plateau yield of 3580 kg ha^?1 when plants contained 197 kg N ha^?1, 33 kg S ha^?1 and 200 g B ha^?1, with a seed B content of 60 g B ha^?1. The critical N, S, and B values identified in this work and their potential for a posteriori nutrient diagnosis of canola should be useful to validate fertilizer requirements for canola production in eastern Canada.     

A simple,low‐cost technique for in situ measurement of leaf P concentration in field‐grown rice

Simple tools for diagnosing crop nutritional status are in great demand by agricultural extension staff, particularly in low‐fertility environments. We developed the first practical method for in situ diagnosis of phosphorus (P) nutrition in field‐grown cereal crops by using a handheld colorimeter. The concentration of P in extracts from fresh leaves of lowland rice grown under various P availabilities was closely correlated with that of oven‐dried leaves measured with the standard molybdenum‐blue method in the laboratory, over a range of values from 0.319 to 1.420 mg P g ^?1 DW (r = 0.885^**, n = 14). It takes only 3–5 min to estimate the P concentration of plant samples using the new technique. Although not as accurate as the laboratory method, the new method can easily detect P deficiency of rice in the field (and possibly other cereal crops) without requiring costly, off‐site equipment. Thus, extension staff and agronomists can easily adopt this technique.     

Extraction of mobile element fractions in forest soils using ammonium nitrate and ammonium chloride

The extraction of earth alkaline and alkali metals (Ca, Mg, K, Na), heavy metals (Mn, Fe, Cu, Zn, Cd, Pb) and Al by 1 M NH₄NO₃ and 0.5 M NH₄Cl was compared for soil samples (texture: silt loam, clay loam) with a wide range of pH(CaCl₂) and organic carbon (OC) from a forest area in W Germany. For each of these elements, close and highly significant correlations could be observed between the results from both methods in organic and mineral soil horizons. The contents of the base cations were almost convertible one‐to‐one. However, for all heavy metals NH₄Cl extracted clearly larger amounts, which was mainly due to their tendency to form soluble chloro complexes with chloride ions from the NH₄Cl solution. This tendency is very distinct in the case of Cd, Pb, and Fe, but also influences the results of Mn and Zn. In the case of Cd and Mn, and to a lower degree also in the case of Pb, Fe, and Zn, the effect of the chloro complexes shows a significant pH dependency. Especially for Cd, but also for Pb, Fe, Mn, Zn, the agreement between both methods increased, when pH(CaCl₂) values and/or contents of OC were taken into account. In comparison to NH₄Cl, NH₄NO₃ proved to be chemically less reactive and, thus, more suitable for the extraction of comparable fractions of mobile heavy metals. Since both methods lead to similar and closely correlated results with regard to base cations and Al, the use of NH₄NO₃ is also recommended for the extraction of mobile/exchangeable alkali, earth alkaline, and Al ions in soils and for the estimation of their contribution to the effective cation‐exchange capacity (CEC). Consequently, we suggest to determine the mobile/exchangeable fraction of all elements using the NH₄NO₃ method. However, the applicability of the NH₄NO₃ method to other soils still needs to be investigated.     

赣南华盛顿脐橙果实发育中几种矿质营养含量动态的研究

赣南红黄壤的土壤条件导致柑橘树体缺素现象比较普遍,而华盛顿脐橙缺素症状并不明显.本文以赣南华盛顿脐橙为试验材料,对其果实发育中果实不同部位(果皮和果肉)的B、Ca、K、Mg和叶片(越冬老叶和当年春梢叶)的B、Ca、K、Mg、Fe、Mn和Zn含量变化进行了对比测定.结果表明:果皮和果肉B含量均于果实膨大期出现显著上升高峰;而对应的Ca含量在幼果期至果实膨大初期相对较高,之后趋明显下降.老叶的B、Ca、Fe和Mn含量均相对稳定,对应春梢叶四者含量均于花后100 d(高温干旱期)出现大幅度下降,之后呈类似的变化趋势;而春梢叶的K、Mg和Zn含量并无此显著下降过程,且老叶的Mg和Zn含量均低于缺乏临界值.     

湖南烟区土壤pH分布特点及其与土壤养分的关系

测试分析了湖南烟区1089个土壤样本的pH,并分析了其与土壤养分的关系。结果表明：湖南烟区土壤pH总体适宜,平均为6．52,变异系数为16．81％;pH处于最适宜烤烟生长的5．5～6．5间的土壤样本占总样本数的26．91％;pH处于适宜烤烟生长的5．0～7．0间的土壤样本占52．71％。湖南不同烟区土壤pH大小表现为：湘南〉湘北〉湘西〉湘东;烟区不同土壤类型pH大小表现为：鸭屎泥〉黄壤土〉青泥田〉黄灰土〉黄泥田〉红黄泥。土壤pH与土壤有机质、全氮、速效磷、速效钾、有效锌、有效铁、水溶性氯、交换性钙和交换性镁的相关性均达1％极显著水平。土壤pH分组后,土壤养分含量在组间存在极显著差异。湖南烟区pH在5．5～6．5间的土壤的有机质、全氮、速效磷、有效锌和水溶性氯含量能够满足优质烤烟生长需求,有效锰、有效铁、交换性钙和交换性镁含量能满足烤烟的正常生长需求,有效钾和有效铜含量偏低,但尚未引起烤烟的缺素症状。     

基于ASI法的滨海滩涂地水稻测土推荐磷、钾施用量的验证

运用土壤养分状况系统研究法(ASI)进行土壤测定和水稻肥料推荐,通过田间小区试验对滨海滩涂地水稻推荐磷、钾施用量进行验证。结果表明,在其它营养元素的施用量均在最佳推荐量条件下,ASI法测土推荐的磷(P2O5)、钾(K2O)最佳施用量(90 kg/hm2、105 kg/hm2)处理的水稻有效分蘖数、穗实粒数、千粒重及产量均是最佳的;且施磷能够显著增加水稻的有效分蘖数,施钾能够显著增加水稻穗粒数和千粒重,最终达到增产的目的。因此,运用ASI法对滨海滩涂地水稻进行测土推荐磷、钾肥的施用量是基本合理的。     

Effects of dietary rosemary extract supplementation on growth performance,nutrient digestibility,antioxidant capacity,intestinal morphology,and microbiota of weaning pigs

Rosemary (Rosmarinus officinalis L.) extract (RE) has multiple pharmacological and biological activities, including the use as a food additive and medicine. This study was conducted to investigate the effects of dietary RE supplementation on the growth performance, nutrient digestibility, antioxidant capacity, intestinal morphology, and microbiota of weaning piglets. A total of 192 crossbred weaned piglets [Duroc × (Large White × Landrace)] (initial body weight = 6.65 ± 0.33 kg, weaned days = 23 ± 1 d) were group housed (six pigs per pen; n = 8 pens/treatment). Pigs were fed a corn–soybean meal-based control diet or the basal diet supplemented with 100, 200, or 400 mg/kg RE. Pigs were allowed ad libitum access to fed for 21 d. The growth performance and apparent total tract digestibility of nutrients, and intestinal morphology and antioxidant status were evaluated. The components of the microbial microflora were also determined in the cecal samples. Compared with the control, dietary supplementation with RE increased the final body weight, average daily gain, and average daily feed intake (linear, P = 0.038, 0.016, and 0.009, respectively), and decreased the diarrhea ratio in piglets (linear, P < 0.05). The digestibility of crude protein (linear, P = 0.034) and gross energy (linear, P = 0.046) increased with treatment with RE. Piglets fed RE showed longer villus height (linear, P = 0.037 and 0.028, respectively) and villus height/crypt depth (linear, P = 0.004 and 0.012; quadratic, P = 0.023 and 0.036, respectively) in the jejunum and ileum, in addition to a lesser crypt depth in the jejunum (linear, P = 0.019) and ileum (quadratic, P = 0.042). The addition of RE increased the activity of superoxide dismutase (linear, P = 0.035 and 0.008, respectively) and glutathione peroxidase activity (linear, P = 0.027 and 0.039, respectively) and decreased the content of malondialdehyde (linear, P = 0.041 and 0.013; quadratic, P = 0.023 and 0.005, respectively) in the serum and liver. Dietary RE supplementation, compared with the control, increased the number of Bifidobacterium (linear, P = 0.034) and Bacteroidetes (linear, P = 0.029), while decreased Escherichia coli (linear, P = 0.008; quadratic, P = 0.014) in the cecal contents. Thus, dietary RE supplementation can improve growth performance, nutrient digestibility, antioxidant capacity, intestinal morphology, and the microbiota in weaned piglets, and 200 mg/kg may be considered the optimum dosage.     

草坪草分蘖特征及调控机理研究进展

分蘖是草坪草的重要特征之一,直接影响草坪草的耐践踏性及坪用价值。从草坪草分蘖类型、形成过程及分蘖形态特征等方面阐述了草坪草的分蘖特征,并从生长素、细胞分裂素等内源激素及碳水化合物,氮素等营养物质的类型和含量分析探讨了影响草坪草分蘖的调控机理。以期为草坪草分蘖调控机制的进一步研究及针对性地提出养护对策提供参考。     

连茬栽培对人工营养土理化性质及番茄产量的影响

通过利用当地的玉米秸秆为主要材料与土壤、草炭分别按不同的比例配制的人工营养土与土壤做比较,通过物理化学的方法检测所配人工营养土的营养成分、物理化学特性的好坏,并在日光温室内对番茄进行试验,研究所配制的人工营养土对番茄的生长发育、产量和各种品质的影响。研究结果表明,人工营养土栽培可以在很大程度上改善番茄植株的产量。在本试验所做的四个处理中,处理B:土:玉米秸秆=1:2+鸡粪(15kgm-3)和处理D:草炭:玉米秸秆=1:2+鸡粪(15kgm-3)的处理效果较好,考虑到经济和节省资源等因素,建议在生产中应用处理B:土:玉米秸秆=1:2+鸡粪(15kgm-3)。     

皖南烟叶香气成分因子及关联度分析

为探讨各类香气物质对皖南地区烟叶特殊香型形成的作用,本试验对皖南地区四种典型土壤所产烟叶香气进行了因子分析,及香气综合评定值与土壤养分的关联度分析。结果表明:利用因子模型在阐明以因子形式表现的香气物质变量间的关联时,可信度高。因子分析证明类胡萝卜素类物质降解产生的香气物对烤烟香气影响最显著,可推断烤烟的香气特色主要是由烟叶中类胡萝卜素类降解产物的量及协调程度决定的,这其中又以巨豆三烯酮最为重要。在皖南地区烟株生长及香气品质形成过程中,土壤pH值起重要作用,土壤速效钾、全磷影响作用逐渐增加,碱解氮、有机质影响作用逐渐降低。