Absorption of Nitrogen, Phosphorus, and Potassium from Nutrient Sprays by Leaves

Barley, Brussels sprout, French bean, tomato, and sugar-beetplants grown in soil in pots and sprayed, usually daily, forseveral weeks, with nutrient solutions containing nitrogen,phosphorus, potassium, and a spreader, with precautions to preventthe spray solution falling on the soil, had higher nutrientcontents and dry weights than control plants sprayed with waterand spreader only. Increase in nutrient content occurred withhigh or low levels of nutrient supply to the roots and was approximatelyproportional to the concentration of spray and to the frequencyof spraying. The nitrogen content of sugar-beet plants was increased equallyby spraying with solutions supplying ammonium sulphate, calciumnitrate, or urea in equivalent concentrations. Nutrient uptake from solutions sprayed on leaves influenceduptake by the roots so that the additional amounts of nutrientcontained in sprayed plants may be greater or smaller than theamount absorbed from the spray by the leaves.     

The Effect of Applying a Nutrient in Leaf Sprays on the Absorption of the Same Nutrient by the Roots

Ammonium nitrate solution applied to the leaves of sugar-beetincreased plant dry weight and uptake of nitrogen by the roots.Uptake of phosphorus by the roots of swedes, but not sugar-beet,grown with high phosphorus supply to the roots, was decreasedby applying sodium phosphate solution to the leaves; uptakefrom a lower phosphorus supply to the roots was unaffected.Phosphorus applied to the leaves had no effect on dry weight.Potassium uptake by the roots of sugar-beet plants grown withhigh potassium supply to the roots was unaffected by paintingthe leaves with a potassium chloride solution, that of plantswith an intermediate potassium supply was increased, and plantsgrown with a low supply to the roots absorbed almost all theavailable potassium so painting could not much increase uptakeby the roots. Application of potassium to the leaves increaseddry weight of plants with low or medium potassium supply tothe roots and did not affect that of plants with a high potassiumsupply. The top: root ratio for phosphorus content in mg. per plantwas greater for phosphorus absorbed via leaves than for phosphorusabsorbed via roots. Increasing the phosphorus supply to theroots increased this ratio for phosphorus absorbed either vialeaves or roots. Potassium absorbed by leaves was slightly more efficient inincreasing dry weight than potassium absorbed at the same timeby the root. A similar comparison was not possible for nitrogenor phosphorus. The results of these and previous experiments indicate thatall the nitrogen and potassium and over 80 per cent. of thephosphorus applied to leaves was absorbed. The small amountof phosphorus remaining unabsorbed on the surface of the leafwas unaffected by phosphorus supply to the root.     

Competition for Nitrogen and Potassium in Agropyron repens

Stands of Agropyron repens (couch grass) and single young sugar-beetplants were grown in pots, separately and in competition, withnitrogen and potassium each supplied at three rates in a factorialdesign. Both nitrogen and potassium increased relative growth-ratesof sugar-beet leaves and crowns and fresh-weight/dry-weightratios of all plant parts; the responses were usually curved,the high nutrient levels having little more effect than theintermediate levels. Competition decreased relative growth-ratesand freshweight/dry-weight ratios of all plant parts and alsoleaf-area ratio (F) and net assimilation rate (E). High ratesof nitrogen diminished the effects of competition on relativeleaf growth-rate, F, and on fresh-weight/dry-weight ratios,indicating competition for nitrogen, but high rates of potassiumdiminished only its effect on relative growth-rate of the crown,suggesting that competition for potassium had only a small effect. Competition depressed leaf nitrogen and potassium percentagesand total nitrogen and potassium uptake by the whole plant,but the depressions were small at high rates of nutrient supply,suggesting that the amounts of nitrogen and potassium availablewere nearly adequate for both sugar-beet and A. repens. When total dry weights and leaf areas of sugar-beet were comparedwith corresponding nutrient contents, variation in nitrogencontent alone could account for most of the effects of competitionon growth, but potassium depletion probably also contributeda little. E was correlated with potassium, but not nitrogen,per unit leaf area, but potassium differences could not adequatelyaccount for the effects of competition on E. Competition for potassium produced small effects compared withcompetition for nitrogen, in spite of large responses to addedpotassium, perhaps because potassium moves less readily in thesoil.     

Nutrient Cycling in Hampsfell Bracken Grassland Ecosystem,England

The nutrient flow in bracken stands during year showed an inerement of nutrients in standing crop from winter to autumn, reabsorbing the nutrients by plants from soil. In autumn the senescence of live fronds results in a loss of nutrients to standing dead and the nutrients in some below ground standing crop is lost to dead rhizomes. Annual uptakes were estimated to be 17.6 g/m2 potassium, 16.4 g/m2 nitrogen, 12.8 g/m2 calcium, 3.14 g/m2 manganese, 2.47 g/m2 iron, 2.12 g/m2 phosphorus. Compared the annual uptake of elements by bracken with nutrient budget in soil, the efficiency of elements absorbed from soil varied from 0.012 for nitrogen to 1.36 for iron.     

施氮和秸秆还田对晚播小麦养分平衡和产量的影响

在大田条件下,研究了水稻秸秆还田和施氮量对晚播小麦产量、养分积累、秸秆养分释放及养分平衡的影响.结果表明: 水稻秸秆还田并配施适当的施氮量有利于提高晚播小麦籽粒产量.晚播小麦全生育期的干物质、氮、磷、钾积累量均随施氮量增加而显著增加,相同施氮量(270 kg N·hm^-2)下,秸秆还田处理的干物质、磷、钾积累高于不还田处理,氮积累则呈相反趋势.随着施氮量增加,秸秆腐解和养分释放率增加,且拔节后秸秆养分释放量占总释放量的比例降低;随生育进程的推进,秸秆的干物质、磷、钾释放量呈倒“N”型变化趋势,而氮释放量则呈“V”型变化趋势.计算养分表观平衡结果表明,秸秆还田并增加施氮量,养分总盈余量显著升高;在获得较高产量的施氮条件下,氮、钾素显著盈余,磷素投入较为合理.晚播小麦实行秸秆还田后,可适当增加氮肥用量至257 kg·hm^-2,并减少钾肥投入.     

THE EFFECT OF ORGANOPHOSPHORUS INSECTICIDAL SPRAYS ON THE GROWTH AND PHOSPHORUS CONTENT OF BRUSSELS SPROUTS

No evidence was found that the insecticides schradan or demeton directly increase the growth of plants. The dry weight of Brussels sprouts plants grown in soil supplying little phosphorus was unaffected by spraying six times with schradan or demeton, or with sodium phosphate Solution supplying the same amount of phosphorus as the insecticides. The dry weight of larger plants grown in soil supplying more phosphorus was unaffected by spraying with demeton or inorganic phosphorus Solutions; schradan spray decreased it in one experiment but not in the other.
Spraying with schradan, or with the equivalent amount of phosphorus as sodium phosphate, in one experiment increased the phosphorus content of plants grown in soil supplying little phosphorus. With high phosphorus supply in the same experiment, sodium phosphate Solution, but not schradan, increased phosphorus content of the plants slightly, but not significantly. Phosphorus content was not affected either by schradan sprays in the other experiment or by demeton sprays in both experiments.     

GROWTH AND NUTRITION OF TIMOTHY (PHLEUM PRATENSE L.): IV. THE EFFECT OF NITROGEN, PHOSPHORUS AND POTASSIUM SUPPLY ON GROWTH DURING THE FIRST YEAR

In a sand-culture experiment lasting 21 weeks plants of timothy grown from seed were maintained at all combinations of three levels of nitrogen, phosphorus and potassium. The number and weight of tillers, leaves and ears, and the weight of roots, were determined at the end of the experiment, and for some of the treatments at intervals of 4 weeks. All three nutrients had significant effects, especially N which at its lowest level of supply tended to mask the effect of the other two elements. Potassium influenced tiller numbers least, especially those of primary tillers, but in the presence of high concentrations of N and P it had a large effect on leaf area and dry weight. Relative growth and net assimilation rates responded to varying nutrient supply only in the early stages of growth, so that in general variations in dry weight were associated with nutrient effects on leaf area.     

甘南高寒草甸植物元素含量与土壤因子对坡向梯度的响应

通过测定甘南高寒草甸不同坡向条件下25科86种植物叶片氮(N)、磷(P)、钾(K)含量、有机碳(C)含量、叶片含水量和相对叶绿素(SPAD)值,以及不同坡向的土壤含水量、有机碳、全氮、全磷含量等土壤指标,分析了不同坡向植物叶片元素含量与土壤环境因子之间的关系。研究结果表明,在南坡-北坡梯度上,随着土壤含水量的增加,植物叶片P含量、叶K含量和叶片含水量显著增加,而相对叶绿素显著降低。土壤养分含量与植物叶片P、叶K含量和叶含水量显著正相关,与叶片相对叶绿素显著负相关。说明不同坡向条件下叶片养分含量受土壤因子的影响显著,土壤的水分及养分状况对植物叶片元素含量的贡献不同。土壤含水量是坡向梯度上影响植物叶片特征的最主要因子。坡向梯度上土壤含水量对植物叶片各种元素含量的影响和植物叶片含水量对不同土壤因子的响应模式支持了生长在南坡的植物能以提高水分和养分利用效率而适应南坡较为干旱和贫瘠的生境。     

Effect of salinity on growth,water use and nutrient use in radish (Raphanus sativus L.)

Radish (Raphanus sativus L.) plants were grown at five soil salinity levels (1, 2, 4, 9 and 13 dS m^-1) to analyse the effects on growth, dry matter partitioning, leaf expansion and water and nutrient use. Salinity was varied by proportionally changing the concentration of all macro nutrients. When the electrical conductivity (EC) of the soil solution increased from 1 to 13 dS m^-1, the influx concentration of the nutrients absorbed by the plants (the ratio between the uptakes of nutrients and water) increased only from 1.6 to 3.5 dS m^-1. The total nutrient uptake showed an optimum at an EC of the soil solution of about 4 dS m^-1. The data suggest that at low salinity level (≤ 2 dS m^-1) the nutrient uptake was limited by availability while at high salinity (>4 dS m^-1) it was limited by the growth of the plant. Total water use by the plants decreased and water use efficiency increased at high salinity. Plant growth was optimal at 2–4 dS m^-1. At salinities higher than 4 dS m^-1 total plant dry weight decreased 2.8% per dS m^-1. About 80% of the growth reduction at high salinity could be attributed to reduction of leaf area expansion and hence to reduction of light interception. The remaining 20% of the salinity effect on growth was most likely explained by a decrease in stomatal conductance. The small leaf area at high salinity was related to a reduced specific leaf area and increased tuber/shoot weight ratio. The latter could be attributed to tuber formation starting at a smaller plant size at high salinity. This revised version was published online in June 2006 with corrections to the Cover Date.     

Combined effects of partial root drying and patchy fertilizer placement on nutrient acquisition and growth of oilseed rape

Partial rootzone drying (PRD) is widely investigated as an effective irrigation technique, resulting in higher water use efficiency and yield for plants growing under mild water deficit. Nutrition is another important factor affecting plant yield, but nutrient acquisition has only rarely been considered in conjunction with PRD. Here we investigate the interaction between water and fertilizer supply in a pot experiment with oilseed rape (Brassica napus L.). Eight treatments were set up for the experiment, a factorial combination of four watering regimes (100% control watering at both sides of the plants; 50% control watering at both sides of the plants; 50% fixed watering applied only to one side of the plants; 50% alternate watering applied alternately to both sides of the plant) and two fertilizer placement levels (uniform over the entire pot, and patchy supplied to one side). For the 50% watering treatments, the total amount of water supplied to the plants was the same, only the pattern of application differed between treatments. Also the total fertilizer applied was the same for all treatments. Oilseed rape roots foraged effectively for water and nutrients resulting in relatively small differences in nutrient uptake and above-ground growth among the water-deficit treatments. Placing fertilizer at one side of the plants increased nutrient uptake, but there were differences between the water treatments and interactions with water uptake. Alternate watering resulted in the highest growth, as a result of the largest nitrogen and phosphorus uptake with the smallest root investment among the three water deficit treatments. Fixed watering resulted in poorest performance when fertilizer was uniformly spread throughout the pot, because the plants were unable to acquire the nutrients on the dry side. Our results show that PRD can be well combined with patchy fertilizer supply, but that reduced nutrient uptake may be expected when nutrients are supplied in parts of the soil volume that remain too dry. Responsible Editor: Yan Li     

有机肥对粉垄蔗地土壤养分及甘蔗产量品质的影响

为了研究施用有机肥对粉垄条件下甘蔗产量和品质的影响,该研究以蚯蚓粪、猪粪分别与复合肥配施于粉垄蔗地中,并以单施复合肥作为对照,研究有机肥与复合肥配施对粉垄土壤理化性状及甘蔗养分、产量、蔗茎品质的影响.结果表明:(1)与对照相比,有机肥与复合肥混施可在不同时期分别提高粉垄土壤有机质、全氮、全磷、碱解氮、速效磷、速效钾含量...     

黑土长期施肥及养分循环再利用的作物产量及土壤肥力质量变化Ⅲ.土壤养分收支

许了1985－1999年试验期间各模拟施肥模型的作物移出养分量和施肥输入养分量,结果表明,施用N肥可加剧土壤P收支赤字,而施用N,P肥则加剧土壤K收支赤字,实验展示了我国在20世纪70年代大面积贫P土壤和80年代大面积缺K土壤出现的原因,保持养分循环再利用可缓解土壤养分收支赤字,但不能满足丰产作物的养分需求,在保持养分循环利用基础上根据土壤肥力适当施用化肥,可满足丰产作物的养分需求和平衡土壤养分收支,不致发生大量过剩N进入环境。     

小麦开花期灌水对土壤养分及根系分布的影响

本研究通过分析开花期灌水对小麦产量、植株养分分配和土壤养分分布的影响及其与根系特性的关系,为小麦充分利用水肥资源提供理论支撑。以抗旱高产品种‘洛麦28'和高光效品种‘百农207'为材料,采用2 m深土柱栽培方法,设置开花期灌水(T₁)和开花期不灌水(T₂)两个水分处理,测定了不同组织器官、不同土层土壤氮、磷、钾含量及根系分布特性等指标。结果表明: 小麦收获期土壤中铵态氮、速效磷和速效钾主要分布在0～80 cm土层中,硝态氮主要分布在80 cm以下土层中,开花期灌水促进小麦吸收0～60 cm土层的铵态氮、速效磷、速效钾和80 cm以下土层的硝态氮,减少了硝态氮向深层土壤的淋溶;小麦根系主要集中在0～60 cm土层中,随土壤深度的增加而减少。成熟期干物质积累量、全氮和全磷主要分配在小麦籽粒中,而全钾主要分配在茎秆中;开花期灌水显著增加了小麦百粒重,提高了小麦产量;根系形态指标与土壤硝态氮在0～40 cm土层中呈显著负相关,与土壤铵态氮在80～100 cm土层中呈极显著正相关,与土壤速效磷在0～100 cm土层中呈显著正相关。开花期灌水促进了根系在小麦生育末期对土壤养分的充分吸收,延长了养分从营养器官向生殖器官的转运功能期,使营养器官中的养分充分地转运到籽粒中去,增加小麦粒重,进而提高产量。     

Dry matter production and partitioning in potato plants subjected to combined deficiencies of nitrogen, phosphorus and potassium

Three experiments examined effects on growth, dry matter partitioning and nutrient uptake in potato plants grown in large pots under different combinations of adequate and deficient levels of nitrogen, phosphorus and potassium. N supply affected the growth of all leaves, with low N reducing both the size of individual leaves and the extent of branch growth. P and K availability affected the growth of later formed leaves and only when both were deficient was branch growth substantially reduced. At later stages of growth, total green leaf area was significantly reduced by deficiency of each of the nutrients. Partitioning of dry matter to tubers was markedly reduced by K deficiency and increased in one experiment by P deficiency. When both P and K were deficient, partitioning approximated that under non‐limiting conditions. Leaf weight ratio (LWR) was higher under K deficiency, but not when P was also deficient, and was consistently higher when the ratio of K : P in dry matter was less than approximately five. In these experiments, LWR was not consistently related to shoot N% and N supply had relatively little effect on partitioning. There were large treatment effects on tuber dry matter percentage, characterised by significant interactions especially between N and K. Deficiency of one nutrient increased the concentration of others but uptake was highly regulated as crop content of all three nutrients was reduced when the supply of any one was deficient. The results show that the response of potatoes to single deficiencies may be influenced greatly by the levels of other nutrients.     

Foliar nutrient dynamics and nutrient use efficiency in Cornus florida

Summary Growth rates and seasonal changes in foliar nitrogen, phosphorus, and calcium of Cornus florida L. (flowering dogwood) individuals were determined in three forest stands which differed in soil moisture and soil nutrient availability. Nutrient use efficiency of individual trees was measured by amount of leaf dry mass produced per unit nutrient invested, rates of nutrient resorption prior to litterfall, wood and leaf mass produced per unit nutrient turnover (=growth efficiency), projected uptake needs, and losses of nutrients to simulated throughfall leaching. Relative growth rates during this drought year, as determined by dimension analysis, were highest in the site with highest soil moisture, while 5-year average relative growth rates were highest in the most fertile site. Differences in nitrogen use efficiency were generally small, with the highest efficiencies in trees on the moistest site; in contrast, phosphorus use efficiency was consistently highest on the least fertile site. Foliar calcium levels increased throughout the year and calcium use efficiency was generally highest on the least fertile site. These data suggest that growth and nitrogen use efficiency were more strongly affected by differences in soil moisture than were phosphorus or calcium use, at least during this very dry year.     

施蚯蚓粪对日光温室土壤及番茄产量与品质的影响

设施蔬菜化肥过量施用造成土壤劣化、土传病虫害发生严重,从而导致蔬菜产量和品质下降。蚯蚓粪在改善土壤环境和促进蔬菜生长、提高产量和品质方面具有良好的效果。本试验在日光温室采用等量撒施和沟施两种方式研究了增施蚯蚓粪对土壤养分、酶活性、微生物数量及番茄生长、产量和品质的影响。结果表明: 与不施蚯蚓粪的对照相比,撒施蚯蚓粪和沟施蚯蚓粪处理均改善了土壤环境,显著增加了土壤有机质和氮、磷、钾等养分含量;显著提高了蔗糖酶和过氧化氢酶活性,增加了土壤中细菌、放线菌数量,降低了真菌数量。沟施蚯蚓粪处理明显促进了植株地上部的生长,撒施效果不显著。蚯蚓粪处理明显增强了植株根系活力,提高了叶片的光合作用和叶绿素含量,促进了植株氮和钾含量的积累。撒施和沟施蚯蚓粪处理的番茄产量比对照分别提高了22.7%和32.6%。沟施处理果实中可溶性蛋白、可溶性糖、维生素C和可滴定酸含量分别提高了66.1%、11.0%、122.6%和29.9%,硝酸盐含量降低了65.7%,而撒施处理对番茄果实品质提升效果不明显。     

Transpiration, potassium uptake and flow in tobacco as affected by nitrogen forms and nutrient levels

BACKGROUND AND AIMS: Ammonium can result in toxicity symptoms in many plants when it is supplied as the sole source of N. In this work, influences of different nitrogen forms at two levels (2 and 15 mm N) on growth, water relations and uptake and flow of potassium were studied in plants of Nicotiana tabacum 'K 326'. METHODS: Xylem sap from different leaves was collected from 106-d-old tobacco plants cultured in quartz sand by application of pressure to the root system. Whole-shoot transpiration for each of the treatments was measured on a daily basis by weight determination. KEY RESULTS: Total replacement of NO(3)(-)N by NH(4)(+)-N caused a substantial decrease in dry weight gain, even when plants grew under nutrient deficiency. Increasing nutrient concentration resulted in a greater net dry weight gain when nitrogen was supplied as NO(3)(-) or NH(4)NO(3), but resulted in little change when nitrogen was supplied as NH(4)(+). NH(4)(+)-N as the sole N-source also caused reduction in transpiration rate, changes in plant WUE (which depended on the nutrient levels) and a decrease in potassium uptake. However, the amount of xylem-transported potassium in the plants fed with NH(4)(+) was not reduced: it was 457 % or 596 % of the potassium currently taken up at low or high nutrient level, respectively, indicating a massive export from leaves and cycling of potassium in the phloem. CONCLUSIONS: Ammonium reduces leaf stomatal conductance of tobacco plants. The flow and partitioning of potassium in tobacco plants can be changed, depending on the nitrogen forms and nutrient levels.     

Endophytic fungi (Neotyphodium coenophialum) affect the growth and mineral uptake, transport and efficiency ratios in tall fescue (Festuca arundinacea)

Neotyphodium coenophialuminteracts mutualistically with its host grasses. Tall fescue (Festuca arundinacea Schreb.) plants infected by the fungal endophyte,Neotyphodium coenophialum(Morgan-Jones and Gams) Glenn, Bacon and Hanlin, often perform better than non-infected plants, especially in limited resource environments. However, there is a scarcity of information about endophyte-grass ecotypes interaction in Andisols of temperate regions. Clones of three tall fescue ecotypes (Fukaura, Koiwai and Showa) either infected with N. coenophialum (E+) or noninfected (E–) were grown in Andisols (Black Andisol: naturally low content of phosphorus, high in other nutrients; Red Andisol: naturally high content of phosphorus, low in other nutrients) for 133 days in a controlled environment. Cumulative shoot dry weight, daily regrowth rates (tiller number, plant height and shoot dry matter) after clippings and nutrient uptake, transport and efficiency ratios were measured. In Black Andisol, E+ plants had significantly higher cumulative shoot dry weight as well as daily regrowth rates than E– plants, while in Red Andisol the reverse was true. Among the ecotypes studied, Showa had the highest shoot growth. Significantly higher phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) uptake as well as transport were identified in E+ vs. E– plants grown in Black Andisol. With few exceptions, values for nutrient efficiency ratios were not significantly different between E+ and E– plants grown in both soils. Significant three-way interaction (endophyte × ecotype × soil) for cumulative shoot dry weight and regrowth rate revealed that the ecotype specific regrowth responses to endophyte infection were depended on soil nutrient conditions. Vegetative growth and nutrient acquisition in tall fescue varied with ecotype and were modified by abiotic (soil fertility status) as well as biotic (endophyte infection) factors.     

Effect of nitrogen and phosphorus availability on the growth response of Eucalyptus grandis to high CO2

The response of Eucalyptus grandis seedlings to elevated atmospheric CO₂ concentrations was examined by growing seedlings at either 340 or 660 n mol CO₂ mol^-1 for 6 weeks. Graded increments of phosphorus and nitrogen fertilizers were added to a soil deficient in these nutrients to establish if the growth response to increasing nutrient availability was affected by CO₂ concentration. At 660 μmol CO₂ mol^-1, seedling dry weight was up to five times greater than at 340 μmol CO₂ mol^-1. The absolute response was largest when both nitrogen and phosphorus availability was high but the relative increase in dry weight was greatest at low phosphorus availability. At 340 μmol CO₂ mol^-1 and high nitrogen availability, growth was stimulated by addition of phosphorus up to 76 mg kg 1 soil. Further additions of phosphorus had little effect. However, at 660 μmol CO₂ mol^-1, growth only began to plateau at a phosphorus addition rate of 920mg kg^-1 soil. At 340 μmol CO₂ mol^-1 and high phosphorus availability, increasing nitrogen from 40 to 160mg kg^-1 soil had little effect on plant growth. At high CO₂, growth reached a maximum at between 80 and 160mg nitrogen kg^-1 soil. Total uptake of phosphorus was greater at high CO₂ concentration at all fertilizer addition rates, but nitrogen uptake was either lower or unchanged at high CO₂ concentration except at the highest nitrogen fertilizer rate. The shoot to root ratio was increased by CO₂ enrichment, primarily because the specific leaf weight was greater. The nitrogen and phosphorus concentration in the foliage was lower at elevated CO₂ concentration partly because of the higher specific leaf weight. These results indicate that critical foliar concentrations currently used to define nutritional status and fertilizer management may need to be reassessed as the atmospheric CO₂ concentration rises.     

Growth,chlorophyll and mineral nutrient studies on phalaris arundinaceae L. in three scottish lochs

Growth, chlorophyll and mineral nutrients studies were made in Phalaris arundinaceae L. in three Scottish lochs of varying nutrient status from March to November in 1975. The maximum shoot height and shoot dry weight attained by the plants were approximately 160 cm and 4 g respectively. Seasonal changes in the chlorophyll levels in the Phalaris leaf were studied and two peaks were found, one in April and the other in June–July. Maximum chlorophyll level attained was 9 mg g^–1 leaf dry weight. The changes in the mineral levels in the root, stem, leaf and inflorescence parts of the plants from the three lochs were also assayed throughout the growing season. A total of eight mineral elements were studied, including carbon, nitrogen, phosphorus, potassium, sodium, calcium, magnesium and iron. Variations in both the mineral concentrations and their pattern of changes during the study period among the plants from the lochs were observed and discussed.