Influence of Nitrogen and Sulfur Fertilization on the Alliin Content of Onions and Garlic

Abstract

Onion (Allium cepa L.) and garlic (Allium sativum L.) were among the earliest cultivated crops and have been popular in folk medicine for centuries. Alliins (cysteine sulfoxides) are the characteristic sulfur (S) containing secondary metabolites of Allium species like onions, shallot, garlic, leek and chives and they cause taste and sharpness and are criteria for the pharmaceutical quality. The influence of the S nutritional status on the content of secondary S containing metabolites was shown for different crops such as oilseed rape, mustard, nasturtium, and allium species. It was the aim of this study to investigate the influence of the S and nitrogen (N) supply on the alliin content of onion and garlic and to evaluate the significance for crop quality. In a greenhouse experiment three levels of N and S were applied in factorial combinations of 0, 50, and 250 mg pot^?1 S and 250, 500, and 1000 mg pot^?1 N. 8 plants were grown in a Mitscherlich pot containing 8 kg sand. Leaves and bulbs were sampled twice during the growth period in order to follow up translocation processes. The first sampling was carried out when leaves were developed, but bulb growth had not yet started and the second one during main bulb growth. An increasing S supply was related to an increasing alliin content in leaves and bulbs of both crops, whereas nitrogen fertilization had only a minor influence. The alliin content in bulbs could be doubled by S fertilization. A translocation of alliin from leaves to bulbs was found so that time of harvest has a strong influence on the alliin content. At the beginning of plant development high alliin contents were found in leaves, while with bulb development they were translocated into this plant organ. The results show that the potential health benefits of Allium species could be distinctly improved by S fertilization.     

Changes in organosulfur compounds in garlic cloves during storage

We determined the changes in the contents of three gamma-glutamyl peptides and four sulfoxides in garlic cloves during storage at -3, 4, and 23 degrees C for 150 days using a validated high-performance liquid chromatography method that we reported recently. When garlic was stored at 4 degrees C for 150 days, marked conversion of the gamma-glutamyl peptides, gamma-L-glutamyl-S-allyl-L-cysteine and gamma-L-glutamyl-S-(trans-1-propenyl)-L-cysteine (GSPC), to sulfoxides, alliin and isoalliin, was observed. Interestingly, however, when garlic was stored at 23 degrees C, a decrease in GSPC and a marked increase in cycloalliin, rather than isoalliin, occurred. To elucidate in detail the mechanism involved, the conversion of isoalliin to cycloalliin in both buffer solutions (pH 4.6, 5.5, and 6.5) and garlic cloves at 25 and 35 degrees C was examined. Decreases in the concentration of isoalliin in both the solutions and the garlic cloves during storage followed first-order kinetics and coincided with the conversion of cycloalliin. Our data indicated that isoalliin produced enzymatically from GSPC is chemically converted to cycloalliin and that the cycloalliin content of garlic cloves increases during storage at higher temperature. These data may be useful for controlling the quality and biological activities of garlic and its preparations.     

The dissipation of tebuconazole and propiconazole in boronia (Boronia megastigma Nees)

The broad spectrum, systemic fungicides tebuconazole and propiconazole are used to control rust in boronia (Boronia megastigma Nees). Gas chromatography combined with either a benchtop quadrupole mass spectrometer or a high-resolution mass spectrometer allowed for the monitoring of both pesticides in boronia leaves, flowers, and concrete. Field trials were established at two sites to determine the rate of dissipation of tebuconazole and propiconazole in boronia. At site 1, two application rates of 125 and 250 g active ingredient/hectare (ai/ha) tebuconazole were employed. Treatments were repeated 17 days later. At harvest, 286 days after the final application, tebuconazole was detected at levels of 0.06 +/- 0.05 and 0.5 +/- 0.1 [mg/kg +/- standard error, on a dry matter basis (DMB)] in the leaves collected from plots treated with 125 and 250 g ai/ha of tebuconazole, respectively. The oil produced from the flowers collected at the final harvest had residues of tebuconazole at levels of 0.06 +/- 0.03 and 0.10 +/- 0.08 mg/kg for the 125 and 250 g ai/ha application rates, respectively. Two repeat applications of 125 g ai/ha propiconazole were also used at site 1. Residues of propiconazole were detected at 0.09 +/- 0.03 mg/kg (DMB) 286 days after the final application. At site 2, treatments of 125 g ai/ha of tebuconazole were applied twice. At harvest, 279 days after the final application of tebuconazole, residues were recorded at 0.30 +/- 0.09 mg/kg in the leaves (DMB) while the oil produced had 0.20 +/- 0.07 mg/kg.     

Ryegrass forage yield and quality response to sulfur and nitrogen fertilizer on coastal plain soil

Abstract

Sulfur (S) deficiency has been reported in some upland soils of the southern United States and S application has improved forage quality on the low‐S soils. A field experiment was conducted for three years to determine ryegrass (Lolium multiflorum L.) dry matter yield and forage quality response to S fertilization. Prilled elemental S was applied each year at two rates (0 and 45 kg S/ha) in combinations with three rates of nitrogen (N) (168, 224, and 280 kg/ha). Wet depositions of S in rain were monitored over the seasons. Sulfur fertilization generally did not increase seasonal dry matter yield and plant uptake of S. Nitrogen application generally increased dry matter yield and protein content during the season. Averaged over the three‐year period, however, forage yield and S uptake increased from 7.7 to 10.5 Mg/ha and 13.9 to 18.8 kg/ha, respectively, as N fertilization increased from the lowest to highest treatment rates. Forage dry matter for each harvest ranged from 0.6 to 2.2 Mg/ha, while S, protein, in vitro dry matter digestibility (TVDMD), and N/S ratio tended to decline seasonally from 2.5 to 1.8, 266 to 142, and 795 to 716 g/kg, and 17.8 to 11.9, respectively. Sulfur input from rainfall was small with a three‐year average of 5.8 kg/ha (±0.64 SE). In some locations of the southern United States, S may not be limiting even when applying high rates of N to high‐yielding forages which annually remove large quantities of S. Because of the lack of yield response from S application and low inputs of S from wet deposition, S from sources other than rainfall may have been considerable.     

Effect of selenium treatment on mineral nutrition, bulb size, and antioxidant properties of garlic (Allium sativum L.)

Foliar selenium (Se) treatment of garlic at concentrations of 10, 50, and 100 μg of Se/mL was carried out in open field conditions in 2008 and 2009 in Estonia. Bulb weight and yield structure, content of total Se, S, N, P, K, Ca, and Mg, ascorbic acid content (AAC), pungency, total phenolics, and total antioxidant capacity (TAC) were determined. The highest level of Se decreased total S, K, and Ca in both years; no negative impact on bulb weight was observed. In 2009 Se10 treatment had significantly more bulbs with the largest diameter compared to the other treatments. In 2008, the AAC was decreased by Se50 and the content of total phenolics by all Se treatments; however, TAC was increased. Foliar Se fertilization of garlic at rates of 10-50 μg of Se/mL can be recommended to increase the number of large bulbs and increase bulb antioxidant capacity.     

Glucosinolate concentration in turnip (Brassica rapa ssp. rapifera L.) roots as affected by nitrogen and sulfur supply

Three greenhouse pot experiments were conducted with four different nitrogen (N) treatments (80, 160, 240, and 320 kg ha (-1)) in combination with three sulfur (S) treatments (10, 20, and 60 kg ha (-1)) to study the effects of combined N and S supply on glucosinolate concentration and composition in turnip roots. Total glucosinolate concentration varied widely from 9.7 (N 320S 10) to 91.6 (N 160S 60) mg (100 g) (-1) root fresh weight (FW) and individual glucosinolate concentrations were increased with increasing S supply regardless of the N treatment, whereas enhanced N supply (160 - 320 N ha (-1)) at the high S level (60 kg ha (-1)) did not affect total glucosinolate concentration. In contrast, assumingly attributed to the individual glucosinolate biosynthesis concentration of N-containing tryptophan-derived indole glucosinolate was highest with increased N supply, whereas S-containing methionine-derived aromatic and aliphatic glucosinolates decreased with increasing N supply combined at low S level (10-20 kg ha (-1)).     

过量施氮对旱地土壤碳、氮及供氮能力的影响

【目的】过量施氮会影响土壤有机碳、氮的组成与数量,进而改变土壤供氮能力,但关于西北旱地长期过量施用氮肥后土壤有机碳、氮及土壤供氮能力变化的研究尚缺乏。本文在长期定位试验的基础上,通过分析不同氮肥水平特别是过量施氮条件下土壤硝态氮,有机碳、氮和微生物量碳、氮的变化,探讨长期过量施氮对土壤有机碳、氮及供氮能力的影响。【方法】长期定位试验位于陕西杨凌西北农林科技大学农作一站。在施磷(P2O5)100kg/hm2的基础上,设5个氮水平,施氮量分别为N 0、80、160、240、320 kg/hm2。重复4次,小区面积40 m2,完全随机区组排列。种植冬小麦品种为小堰22。本文选取其中3处理,以不施氮为对照(N0)、施氮量N 160 kg/hm2为正常施氮(N160),施氮量N 320 kg/hm2为过量施氮(N320),分别于2012年6月小麦收获后和10月下季小麦播前采集土壤样品,进行测定分析。【结果】过量施氮导致下季小麦播前0—300 cm各土层硝态氮含量显著增加,平均由对照的2.8 mg/kg增加到15.5 mg/kg;同时,0—60 cm和0—300 cm土层的硝态氮累积量分别由对照的47.2和108.9 kg/hm2增加到76.5和727.7 kg/hm2。过量施氮也增加了夏闲期间0—300 cm土层土壤有机氮矿化量,由对照的72.4 kg/hm2增加到130.7 kg/hm2。但过量施氮未显著增加土壤的有机碳含量,却显著增加了土壤有机氮含量,过量施氮0—20、20—40 cm土层土壤有机碳分别为9.24和5.39 g/kg,有机氮分别为1.05和0.71 g/kg,较对照增加52.2%和54.3%。同样,过量施氮未显著影响0—20、20—40 cm土层土壤微生物量碳含量,其平均含量分别为253和205 mg/kg,却显著提高了0—20、20—40 cm土层土壤微生物量氮含量,由对照的24.1和7.5 mg/kg提高到43.6和16.1 mg/kg。【结论】过量施氮可以显著增加旱地土壤剖面中的硝态氮累积量、夏闲期氮素矿化量、小麦播前土壤氮素供应量和土壤微生物量氮含量,但对土壤有机碳和微生物量碳没有显著性影响,同时过量施氮增加了土壤硝态氮淋溶风险,故在有机质含量低的黄土高原南部旱地冬小麦种植中不宜施用高量氮肥,以减少土壤氮素残留和农业投入,达到保护环境和培肥土壤的目的。     

适宜的氮硫配施提高基质栽培大蒜鳞茎品质

试验采用蛭石-珍珠岩盆栽方式,研究了不同浓度氮(5、10、20 mmol/L,记作N1、N2、N3)、硫(2、4、8 mmol/L,记作S1、S2、S3)配施条件对大蒜鳞茎品质的影响,并采用隶属函数法对大蒜品质进行综合评价,分析鳞茎品质与氮硫互作水平的响应关系。试验结果表明,氮素、硫素对大蒜主要营养成分含量影响不尽相同,氮硫配施能够不同程度提高大蒜鳞茎中可溶性蛋白、VC、大蒜多糖、游离氨基酸的含量,且氮、硫单一因素对大蒜鳞茎品质影响远低于元素间交互作用。但在氮素适宜水平下(10~20 mmol/L),硫素水平对大蒜鳞茎中大蒜辣素含量有显著影响,提高硫浓度能够显著增加大蒜辣素含量,而在硫素浓度过高时(8 mmol/L)则明显抑制该物质合成。隶属函数法综合评价以N3S2处理组大蒜鳞茎品质最优,隶属函数值为0.81,对照组(CK)最差。综合分析可见,无机基质栽培条件下氮硫配施显著影响大蒜鳞茎品质,氮素浓度20 mmol/L(N3)、硫素浓度4 mmol/L(S2)时最利于大蒜鳞茎品质的提升,为大蒜无机基质栽培最佳氮、硫配施水平,且两元素配施存在明显的互作效应。该结论为大蒜栽培氮、硫元素合理配施提供试验指导。     

Dissipation of propiconazole and tebuconazole in peppermint crops (Mentha piperita (Labiatae)) and their residues in distilled oils

The broad-spectrum, systemic fungicides propiconazole (1) and tebuconazole (2) are used to control rust in peppermint (Mentha piperita L.). An analytical method, using gas chromatography combined with detection by high-resolution mass spectrometry, was developed to allow for the simultaneous monitoring of both pesticides in peppermint leaves and oil. Field trials were established to determine the rate of dissipation of tebuconazole and propiconazole in peppermint crops. Three applications of each fungicide were trialed at two rates (125 and 250 g of active ingredient (ai)/ha). At harvest, 64 days after the final application, propiconazole was detected at levels of 0.06 mg/kg and 0.09 mg/kg of dry weight, and tebuconazole was detected at 0.26 and 0.80 mg/kg dry weight, in identical trials. Rates of dissipation of propiconazole and tebuconazole were lower at a second trial site, where three applications of 125 g/ha ai for each fungicide resulted in residue levels of 0.21 mg/kg for both pesticides, detected 89 days after the last application. Propiconazole and tebuconazole were detected in the distilled oil at levels between 0.02 and 0.05 mg/kg and between 0.011 and 0.041 mg/kg, respectively. Propiconazole had a higher tendency to co-distill with the peppermint oil, with 0.7% of that present in the vegetative material ending up in the oil, compared to 0.09% of tebuconazole.     

Cadmium contents of oats (Avena sativa L.) in official variety,organic cultivation,and nitrogen fertilization trials during 1997-1999

The cadmium (Cd) contents of oats (Avena sativa L.) in Finland were examined over a 3 year period in three types of trials: official variety, organic vs conventional cultivation, and nitrogen fertilization trials. Large seasonal and regional variations were found in the Cd concentrations. In official variety trials, the mean Cd contents in 1997, 1998, and 1999 were 0.046, 0.029, and 0.052 mg kg(-1) dry weight (dw), respectively, ranging from 0.008 to 0.120 mg kg(-1) dw. The concentrations were generally well below the maximum permitted level of 0.100 mg kg(-1) fresh weight. No significant differences were found between the organic and the conventional cultivation techniques. Nitrogen (N) fertilization increased the Cd contents of oats especially at high nitrogen rates (160 kg N hectare(-1) (ha)). Significant cultivar differences (p < 0.001) were determined in all trials. Cultivars Salo and Kolbu had consistently higher contents, and Belinda and Roope had lower Cd contents among the different growing conditions. Hence, it is possible to cultivate and develop oat cultivars less likely to accumulate Cd.     

Effects of garlic powders with varying alliin contents on hepatic drug metabolizing enzymes in rats

The anticarcinogenic effect of garlic has been demonstrated in both epidemiologic and experimental studies. In this study, possible mechanisms involved in the anticarcinogenic effect of garlic consumption were assessed by determining its capacity to alter drug metabolizing enzymes, in relation with its alliin content. Rats were fed a diet for 2 weeks containing 5% garlic powders produced from bulbs grown on soils with different levels of sulfate fertilization and therefore containing differing amounts of alliin. Activities of several hepatic enzymes, which are important in carcinogen metabolism such cytochromes P450 (CYP) and phase II enzymes, were determined. Garlic consumption slightly increased ethoxyresorufin O-deethylase and CYP 1A2 levels. In contrast, garlic consumption decreased CYP 2E1 activity and the level of the corresponding isoform. UDP glucuronosyl transferase and glutathion S-transferase activities were increased by garlic powders. The alliin content of the garlic powders was positively correlated with UGT activity although not with other activities. Effects produced by garlic consumption were qualitatively similar to that of diallyl disulfide, a sulfur compound that has been extensively studied. These data could partially explain the chemoprotective effect of garlic.     

Free amino acid and cysteine sulfoxide composition of 11 garlic (Allium sativum L.) cultivars by gas chromatography with flame ionization and mass selective detection

Two garlic subspecies (n = 11), Allium sativum L. var. opioscorodon (hardneck) and Allium sativum L. var. sativum (softneck), were evaluated for their free amino acid composition. The free amino acid content of garlic samples analyzed ranged from 1121.7 to 3106.1 mg/100 g of fresh weight (mean = 2130.7 +/- 681.5 mg/100 g). Hardneck garlic had greater methiin, alliin, and total free amino acids contents compared to softneck garlic. The major free amino acid present in all but one subspecies was glutamine (cv. Mother of Pearl had aspartic acid as the major free amino acid). Cv. Music Pink garlic (a rocambole hardneck variety) contained the most methiin, alliin, and total free amino acids. The solid-phase extraction, alkylchloroformate derivatization, GC-FID, and GC-MS methods used in this study were simple and rapid, allowing 18 free amino acids in garlic to be separated within 10 min.     

减氮控磷稳钾施肥对水稻产量及养分积累的影响

氮、 磷用量偏大,钾肥用量不足不仅影响水稻的正常生长发育,而且导致养分利用率偏低。本文通过田间试验,研究减量施用氮、 磷肥,稳定钾肥投入对水稻产量、 养分积累量和肥料利用率的影响。试验设14个处理,每个处理重复2次。结果表明,氮钾、 磷钾、 氮磷钾配施处理的水稻秸秆生物量和籽粒产量均显著高于不施肥处理（P0.05）; 减氮控磷稳钾处理（N 225 kg/hm2、 P2O5 60 kg/hm2、 K2O 90 kg/hm2）与常规施肥处理相比（N 300 kg/hm2、 P2O5 150 kg/hm2、 K2O 60 kg/hm2）能显著增加水稻秸秆生物量（P0.05）,明显提高千粒重和籽粒产量; 试验还得出,减氮控磷稳钾处理分蘖期地上部氮、 钾含量和秸秆氮、 钾含量显著高于常规施肥处理（P0.05）; 收获期地上部氮、 钾的积累量和氮、 磷的表观利用率显著大于常规施肥处理（P0.05）。适当减少氮、 磷用量, 增加钾肥用量能改善氮、 钾营养状况,促进地上部干物质的积累,提高籽粒产量和氮、 磷表观利用率。N 196.2 kg/hm2、 P2O5 46.5 kg/hm2、 K2O 90 kg/hm2的配施方案具有实际推广应用价值。     

施氮量对黄河滩区棉花叶片生理特性、干物质积累及产量的影响

为探讨黄河滩地植棉适宜的施氮水平,以转双价（Bt Cry1A+CpTI）基因抗虫杂交棉品种中棉所72为试验材料,设置了N 0、 150、 300和450 kg/hm2 4个施氮水平,研究了施氮量对棉花叶片生理特性、 干物质积累及产量的影响。结果表明,随着施氮量的提高,棉花叶面积指数（LAI）,叶片叶绿素和全氮含量,谷氨酰胺合成酶（GS）和超氧化物歧化酶（SOD）活性呈增加的趋势,丙二醛（MDA）含量有下降趋势,进而延缓了叶片的衰老进程。在施氮量为N 300 kg/hm2 时,棉花干物质积累量较大,且分配到生殖器官的比例较高;施氮量过低时,干物质积累量较少;施氮量过高时,有利于营养器官生长,干物质积累量最大,但分配到生殖器官的比例较低。棉花施氮量为N 300 kg/hm2时籽棉产量最高,比不施氮（N 0）和施氮量为N 150 kg/hm2的处理分别增加15.29% 和9 .77%,差异达到显著水平;与施N 450 kg/hm2的处理产量差异不显著。因此,在土壤肥力较低且下层土质沙性较强的黄河滩地,棉花的适宜施氮量为300 kg/hm2。     

Nitrogen supply determines responses of yield and biomass partitioning of perennial ryegrass to elevated atmospheric carbon dioxide concentrations

Perennial ryegrass (Lolium perenne L. cv. Parcour) grown at eight levels of nitrogen (N) fertilization (0–765 mg/pot) was exposed to ambient (390 ppm) and elevated (690 ppm) carbon dioxide (CO₂) concentrations for 83 days. Plants were cut three times and dry matter yields determined for each harvest. At final harvest, dry weight of root and stubble biomass was determined, as N concentrations of all plant fractions were determined. Carbon dioxide enrichment effects on yield and total plant biomass increased with increasing N fertilization. The weaker CO₂‐related yield enhancement at low N supply was due to the plants inability to increase tiller number. Root fraction of total plant biomass at final harvest was increased by high CO₂ and decreased by N supply. Root biomass was significantly increased by CO₂ enrichment and for both CO₂ treatments the N supply for maximum root mass coincided with the N supply for reaching maximum total plant biomass. A significant correlation between root fraction of total plant dry matter and N concentration of total plant biomass, which was not changed by CO₂ enrichment, indicates that biomass partitioning between shoot and root is controlled by the internal N status of the plant.     

Alterations in yield,physicochemical components and mineral composition of onion following organic manure and inorganic nitrogen application

Onion is the one of the most important vegetable crops grown extensively throughout the world; hence, understanding the response of the crop to the form and amount of N provided is of immense importance. In a field experiment, poultry and cattle manure (at 10?t/ha) were compared with four inorganic nitrogen (N) application levels (0, 60, 90 and 120?kg?N/ha), and six combinations of manure and N applications were investigated. Plant growth and total yield (kg/ha) significantly increased, when N application increased from 0 to 120?kg/ha, with or without added poultry manure. Plant height, leaf number and neck thickness were significantly reduced at 0?kg/ha?N plus cattle manure. The bulb ascorbic acid concentration significantly increased with the use of poultry manure (15.94?mg/100?g) and cattle manure (15.94?mg/100?g), compared with 120?kg/ha inorganic N (11.42?mg/100?g). No significant effects were observed on total phenolics and total soluble solids of onion bulbs following the different fertiliser treatments. Cattle manure increased P and K concentrations, whilst poultry manure significantly increased Zn and Fe concentrations in onion bulbs. Onion bulb Ca and Mg concentrations were lower when cattle manure (0.19% and 0.12%) was used than when other organic or inorganic fertilisers were used. Therefore, organic manure increases the concentrations of certain minerals in onions, compared with inorganic N application, without negatively affecting bulb size.     

Corn response to two fertilization rates under Sw Spain conditions

Abstract

Corn cv. PRISMA response (growth, plant composition, and yield) was studied in relation to two fertilizer treatments: the high rate used in irrigated fields in SW Spain (1000 kg/ha 15–15–15 fertilizer plus two applications of 400 kg urea (46%N)/ha); and the same reduced to one‐third. Plant height (～ 290 cm), specific leaf area (0.018 m²/g), ear weight (～210 g), kernel weight per ear (～185 g), and estimated yield (～16 Mg/ha) were similar with both treatments. Plant nutrient contents were similar in the leaf level, with both treatments, although the N content of stalk and kernel (at harvest) were higher (P<0.05) when the high fertilization dose was applied. DRIS indices presented N and S as the more balanced nutrients, and in general the P and Mg contents were comparatively low, and Ca and K comparatively high. Amounts of N and P removed by corn (above‐ground part) were higher than those fertilized at the lower rate. Removed K was considerably higher than the loaded amount, whichever rate of fertilization was considered. When fertilized with a comparatively low rate (for irrigated regimes in SW Spain), the natural reserves of the previously fertilized sandy loam soil used in the assay contributed to achieve a high yield with a high‐yielding corn crop.     

Vegetative responses of silage cats fertilized in the growth chamber with various levels of N and K

Oats (Avena sativa L.) are often harvested for silage in the Great Lakes states. The objective of this research was to obtain additional information on the response of oats to N and K fertilization. ‘Froker’ spring oats were grown from seed under 27 C day/21 C night temperatures in a growth chamber. The soil was a 4:1 mixture of Dodge silt loam soil (Typic Argiudoll) and sand that contained low levels of N and K. The potted plants were fertilized with 0, 50, 100, and 200 kg/ha of N as NH₄NO₃ in all combinations with 0, 200, and 400 kg/ha of K as KC1. Plants were harvested at early inflorescence emergence (43 days after seeding). Fertilization with N significantly increased the dry matter yields (g/pot) of the herbage and total plant, the number of axillary tillers/pot, and herbage N percentage. Root yields were increased only with the first increment of N. Nitrogen fertilization had no significant effect on height of the primary shoots and herbage K percentage. The first increment of K (200 kg K/ha) significantly increased herbage and total plant dry matter yields, while the second increment (400 kg K/ha) gave no further yield increases. However, number of axillary tillers/pot and herbage K percentage were increased significantly with each higher K rate. Potassium fertilization had no significant effect on root yield, primary shoot height, and herbage N percentage. It was concluded that the vegetative growth of oats is very responsive to N fertilization to the highest rate applied (200 kg N/ha), but responds only to the first increment of K (200 kg K/ha).     

Effect of genetic characteristics and environmental factors on organosulfur compounds in garlic ( Allium sativum L.) grown in Andalusia, Spain

The content of organosulfur compounds was determined in selected garlic cultivars grown at four locations in Andalusia, Spain. The organosulfur compounds studied were three γ-glutamyl peptides, namely, γ-l-glutamyl-S-(2-propenyl)-l-cysteine (GSAC), γ-l-glutamyl-S-(trans-1-propenyl)-l-cysteine (GSPC), and γ-l-glutamyl-S-methyl-l-cysteine (GSMC), and four cysteine sulfoxides (alliin, isoalliin, methiin, and cycloalliin). There was a significant effect of the location, cultivar, and garlic ecotype on individual organosulfur compound contents. Purple-type cultivars showed on average the highest contents of GSMC, GSAC, alliin, and methiin but the lowest isoalliin content. The impact of genotype was relatively high for GSAC, whereas this factor hardly contributed to the total variability in alliin and isoalliin content. Planting date had a significant effect on the content of alliin and isoalliin. Discriminant analysis evidenced the ability of organosulfur compounds to distinguish among garlic bulbs from different locations or ecotypes with 81 or 86% accuracy, respectively.     

追施氮肥量对菘蓝根的外形品质、干物质积累及活性成分含量的影响

采用田间小区试验,设5个处理,氮肥用量分别为 225、 450、 675、 900、 1125 kg/hm2,每一个处理3个重复小区,研究不同追施氮肥量对菘蓝的光合参数、 根的外形品质、 干物质积累及活性成分含量的影响,探讨氮肥施用量对菘蓝植株地上部和地下部生长的生理影响,优选菘蓝最佳追施氮肥量。结果表明, 追施氮肥有利于提高菘蓝叶片的净光合速率、 气孔导度、 胞间CO2浓度、 蒸腾速率,可以显著增加菘蓝根主根直径和根长,有明显的壮根效应;而菘蓝总鲜重随着施氮量提高而增加,但超过 900 kg/hm2 后就不再增加;在450 kg/hm2下菘蓝根侧根数最少,低氮（225 kg/hm2）和高氮（900、 1125 kg/hm2）水平下菘蓝根侧根数增加过多,影响了菘蓝根药材外形品质;随着施氮量增加,地上部和地下部干物质积累先增加后下降,而根冠比不断下降,氮肥量为675 kg/hm2 时地上部干物质积累最大,氮肥量为900 kg/hm2 的地下部干物质积累最大,追施氮肥对地上部的促进效应明显高于地下部。施氮量增加,多糖含量先增加后下降,施氮量为 675 kg/hm2 时菘蓝根中多糖含量最高为158.383 mg/g,而(R,S)-告依春含量没有明显的变化规律,氮肥量为900 kg/hm2 时含量最高达到 0.5655 mg/g。为保证菘蓝根产量和药用品质适宜的追施氮肥量是675900 kg/hm2。