烹调方式对菠菜、芥蓝中维生素C、维生素K_1和类胡萝卜素的影响

采用化学测定方法对汽蒸和水焯处理不同时间的菠菜和芥蓝中的维生素C、维生素K1和α-胡萝卜素、β-胡萝卜素和叶黄素含量进行研究。结果表明:1)维生素K1和叶黄素的烹调损失低于10%;2)维生素C在水焯处理后损失较大,在菠菜和芥蓝中的保存率分别为41.6%和61.7%;3)各营养素保存率均以汽蒸烹调更佳。短时汽蒸烹调处理时,无论脂溶性还是水溶性营养素保存率均较高,适宜作为绿叶蔬菜的少油烹调方法。     

蕹菜对土壤环境激素Pb、Cd的吸收效应及相关性分析

采用盆栽试验方法,研究了蕹菜对土壤中重金属类环境激素Pb、Cd的吸收效应,并进行相关性分析,为开展蔬菜重金属污染治理、发展绿色食品和无公害蔬菜提供科学依据。结果表明,土壤中Pb（≤2000 mg/kg）、Cd（≤10.0 mg/kg）对蕹菜株高的抑制作用均不明显,但在最高浓度处理下（Pb 4000 mg/kg,Cd 50.0 mg/kg）,蕹菜株高与空白对照差异显著;土壤中Pb、Cd导致蕹菜地上部减产的最大降幅分别为76.3%和65.8%;随着Pb、Cd投放浓度的增加,蕹菜植株各部位的Pb、Cd含量均呈递增趋势,但地上部对Pb的积累比对Cd的积累弱;蕹菜中Pb、Cd积累量与土壤中Pb、Cd含量相关性显著。     

牛蒡提取物对菠菜生长及品质的影响

通过盆栽试验,研究了牛蒡粗提液、牛蒡寡糖两种牛蒡提取物对菠菜生长及品质的影响。结果表明,喷施牛蒡粗提液和牛蒡寡糖均可增加菠菜鲜重,分别比清水处理的高38.3%、24.7%;同时,提高菠菜Vc、总糖含量,降低菠菜体内硝酸盐、草酸含量。说明牛蒡粗提液和牛蒡寡糖不仅能促进菠菜生长,而且能改善菠菜品质。牛蒡粗提液和牛蒡寡糖相比,牛蒡粗提液的效果优于牛蒡寡糖,而且牛蒡粗提液的成本约为牛蒡寡糖的1/10～1/15。因此,从使用效果及经济效益考虑,牛蒡粗提液的应用前景更佳。     

Comparative Phytoremediation of Chromium‐Contaminated Soils by Fenugreek,Spinach, and Raya

Abstract

A glasshouse investigation was undertaken to evaluate the natural potential of fenugreek (Trigonella foenumgraecum L.), spinach (Spinacia oleracea L.), and raya (Brassica campestris L.) for cleanup of chromium (Cr)–contaminated silty loam and sandy soils. Four kilograms of soil per treatment in earthen pots was treated with five levels of chromium [0, 1.25, 2.5, 5.0, and 10.0 mg Cr kg^?1 soil through dipotassium chromate (K₂Cr₂O₇], equilibrated for 21 days at field-capacity moisture content, and then fenugreek, spinach, and raya were grown for 60 days after seeding. The concentration of diethylene triamine pentaacetic acid (DTPA)‐extractable Cr increased significantly with increasing rate of Cr application in both soils, but the increase was higher in sandy soil than in silty loam soil. The DTPA‐extractable Cr in both soils decreased after harvesting of crops compared to its concentration in soil before sowing of the crops. The decrease in DTPA‐extractable Cr concentration was highest in soil growing raya and least in the fenugreek‐growing soil. The percent reduction in dry‐matter yield (DMY) with increasing levels of added Cr in comparison to the zero‐Cr control was highest for fenugreek (49 and 52%) followed by spinach (36 and 42%) and lowest for raya (29 and 34%) in silty loam soil and sandy soil, respectively. Also, the percent reduction in mean shoot yield of all crops was higher in sandy soil (41%) compared to silty loam soil (36%), when the rate of applied Cr was increased from 0 to 10 mg Cr kg^?1 soil. The DMY of both shoot and root was highest for raya and lowest for fenugreek. The Cr concentration in fenugreek, spinach, and raya increased with increasing level of added Cr in both soils. The concentration of Cr in both shoot and root was highest in raya, followed by spinach and fenugreek. The overall mean uptake of Cr in shoot was almost four times and in root was about two times higher in raya compared to fenugreek. The findings indicated that family Cruciferae (raya) was most tolerant to Cr toxicity, followed by chenopodiacea (spinach) and Leguminosae (fenugreek). Because raya removed the highest amount of Cr from soil, it could be used for pytoremediation of mildly Cr‐contaminated soils.     

Crop yield—nitrate‐N,total N,and total K relationships: Leafy vegetables

Abstract

Pot experiments were conducted to determine effects of applied N on NO₃‐N and total N concentrations in Swiss chard (Beta vulgaris var. cicla) and of applied N, P, and K on Bloomsdale spinach (Spinacia oleracea L.) and on curly mustard (Brassica pervirdis L.). Ammonium nitrate produced greater increases in NO₃‐N and total N concentrations in chard than did sulfur‐coated urea at the same rates of applied N. Both N and K increased yields and NO₃‐N accumulation in spinach and mustard; response to applied P resulted only in decreased NO₃‐N. Both total and NO₃‐N concentrations decreased with dilution and/or assimilation associated with time of growth and higher yields.

An examination of published results with several spinach cultivars indicates that differences in NO₃‐N accumulation attributed to leaf type can also be explained by the higher yields of the low NO₃‐N accumulators. The same is true for differences in NO₃‐N accumulations attributed to light and temperature effects.     

Shoot cadmium concentration of soil‐grown plants as related to their root properties

Cadmium (Cd) is toxic to plants, animals, and humans. However, different plant species growing on the same soil may have very different shoot Cd concentrations depending on properties such as size of the root system, Cd net influx, shoot‐growth rate, Cd translocation from root to shoot, and the ability to affect Cd availability in the soil. To investigate possible reasons for different shoot Cd concentrations maize, sunflower, flax, and spinach were grown on an acid sandy soil (pH<$>_{{\rm{(CaCl}}_{\rm{2}} {\rm)}<$> 4.5, and C_org 2.8%) in a growth chamber with Cd additions as Cd(NO₃)₂ of none, 14, and 40 μmol (kg soil)^–1 resulting in Cd soil‐solution concentrations of 0.04, 0.68, and 2.5 μM. Only the high Cd addition caused a significant growth reduction of flax and spinach. The shoot Cd concentration was up to 30 times higher in spinach than in maize; the other species were intermediate. Of the plant properties studied only the variation of the Cd net influx explained the differences in shoot Cd concentrations. This was due to a decreased (maize, sunflower) or increased (flax) Cd concentration in soil solution or more effective uptake kinetics (spinach).     

菠菜硝态氮累积和还原与植株生长的关系

通过盆栽试验,以两个硝态氮含量差异显著的菠菜品种为供试材料,在不同生长时期,测定了叶柄、叶片干重、水分含量、硝态氮含量及叶片内源和外源硝酸还原酶活性,研究菠菜硝态氮累积和硝酸还原酶活性的动态变化及其与植株生长变化的关系。结果表明,随生长期后移,叶柄、叶片及地上部干重和水分含量先增加而后降低,硝态氮含量则持续降低,低硝态氮累积品种S9的下降更为明显,出苗后52d和62d地上部分别降低了100%和89.7%;叶片内源和外源酶活性则随植株生长量增加而增加,高硝态氮累积品种S4增加（379%和199%）更明显,之后该品种酶活性随植株生长量降低而显著下降,品种S9却显著增加,分别为121%和288%。生长前期,品种S4硝态氮含量、干重增长速率及内源、外源酶活性均显著高于品种S9,内源/外源酶活性比值却明显低于后者;生长后期,除外源酶活性和内源/外源酶活性比值外,品种间差异均不明显。因此,生长前期高累积品种硝态氮含量降低较少,主要原因可能是其内源/外源酶活性比值（70.7%）较低,生长后期该品种的内源/外源酶活性比值（98.2%）显著增加后,硝态氮含量迅速下降进一步证明了这一推测。综合上述结果可知,内源/外源酶活性比值更能揭示植株生长变化引起的品种间硝态氮含量变化差异。     

生物质炭和氮肥配施对菠菜产量和硝酸盐含量的影响

施用生物质炭是提高作物产量和氮肥利用效率的潜在有效措施。以菠菜为供试作物开展盆栽试验,研究了生物质炭与氮肥配施对菠菜产量、组织中硝酸盐含量及养分（氮磷钾）含量的影响。生物质炭设3个水平：C0（0g·kg-1）、C5（5g·kg-1）和C10（10g·kg-1）,氮素3个水平分别为N0（0mg·kg-1）、N1（90mg·kg-1）和N2（120mg·kg-1）。试验结果表明,在N0和N1水平下,施用生物质炭显著提高了菠菜产量,增幅为16.6%～57.3%,而在N2水平下,生物质炭对菠菜产量无显著影响（P〉0.05）。同时,在N1水平下,与C0处理相比,C5和C10处理菠菜组织中硝酸盐含量分别增加了198.7%和233.4%;而在N2水平下,C5和C10处理的硝酸盐增幅分别为8.8%和46.3%。在不同氮素水平下,生物质炭的施用增加了菠菜对氮和钾的吸收,而对磷素吸收的影响不明显。总之,生物质炭与氮肥配施可以提高菠菜产量,明显增加氮肥当季利用效率。     

吸湿-回干和人工老化处理对蕹菜种子发芽的影响

采用培养皿发芽法,研究了吸湿—回干和人工老化处理对蕹菜种子发芽的影响。结果表明,吸湿—回干处理种子10 h,可提高种子活力,促进发芽;蕹菜种子进行短期的人工老化处理,可显著或极显著提高种子活力。     

硒对菠菜、小白菜生长及抗氧化活性的研究

研究了硒对菠菜，小白菜生长及抗氧化活性的影响。结果表明，低浓度硒促进了植株的生长。而高浓度硒则抑制了植株的生长；进一步用DPPH法测定了植株总抗氧化活性的结果发现，硒对植株抗氧化活性的影响与硒对植株生长的影响结果表明基本一致。说明加硒后影响了植株体内的内源抗氧化系统，从而促进或抑制植株生长。