Variation in growth and accumulation of N, K+, Ca2+ and Mg2+ among barley cultivars exposed to various nutrient regimes and root/shoot temperatures

Six cultivars of barley ( Hordeum vulgare L., cvs Salve, Nürnberg II, Bomi, Risø 1508, Mona and Sv 73 608) were exposed for three weeks to combinations of high and low mineral supply and differential root/shoot temperature. For all the parameters tested [fresh and dry weights, contents and levels of N, K⁺, Ca²⁺ and Mg²⁺, and influx of Rb⁺(⁸⁶Rb)] the cultivar differences were influenced by the mineral supply, the root temperature and the age of the plants.
The cultivar differences in N nutrition of three-week-old plants could partly be attributed to variation in root size, uptake of N and in use-efficiency of the element. The cultivar variation in root-shoot partitioning of N was small, except when low mineral supply was combined with a low root temperature. Similarly, cultivar differences in contents of K⁺, Ca²⁺ and Mg²⁺ were influenced by variation in uptake, use-efficiency and root/shoot partitioning of the elements. Low root temperature increased cultivar variation in K⁺, Ca²⁺ and Mg²⁺ partitioning.
The modern cultivar Salve was compared with Nürnberg II, which is derived from a German land race. Nürnberg II performed better than Salve when low root temperature and restricted mineral supply were combined. Otherwise Salve grew better, partly due to a more efficient use of N.
Two high-lysine lines, Risø 1508 and Sv 73 608, were compared with their mother lines Bomi and Mona. The differences obtained revealed no general effect of the high-lysine genes on growth and mineral nutrition of up to three-week-old barley plants.     

Growth responses of tropical forage plant species to vesicular-arbuscular mycorrhizae

Summary Growth and mineral uptake of twenty-four tropical forage legumes and grasses were compared under glasshouse conditions in a sterile low P oxisol, one part inoculated and the other not inoculated with mycorrhizal fungi. Shoot and root dry weights and total uptake of P, N, K, Ca, and Mg of all the test plants were significantly increased by mycorrhizal inoculation. Mycorrhizal inoculation, with few exceptions, decreased the root/shoot ratio. Non-mycorrhizal plants contained always lower quantities of mineral elements than mycorrhizal plants. Plant species showed differences in percentage mycorrhizal root length and there was no correlation between percentage mycorrhizal infection and plant growth parameters. A great variation in dependence on mycorrhiza was observed among forage species. Total uptake of all elements by non-mycorrhizal legumes and uptake of P, N and K by non-mycorrhizal grasses correlated inversely with mycorrhizal dependency. Mycorrhizal plants of all species used significantly greater quantities of soil P than the nonmycorrhizal plants. Utilization of soil P by non-mycorrhizal plants was correlated inversely with mycorrhizal dependency.     

Accumulation, Partitioning and Redistribution of Dry Matter and Mineral Nutrients in Ixia flexuosa L., with Special Reference to its Cormaceous Habit

The seasonal dynamics of uptake, partitioning and redistributionof dry matter, N, P, K, S, Ca, Mg, Na, Cl, Fe, Zn, Mn and Cuby the cormaceous plant Ixia flexuosa were studied in pot cultureat Perth, Western Australia. Dry matter and P, N, K, Zn andCu were redistributed from the mother corm with about 90 percent net efficiency: there was no net redistribution of Ca,Na, Fe or Mn. The efficiency of redistribution from the leafyshoot to fruits and the new season's corm was 80 per cent forN and P, 24–49 per cent for K, Cu and Zn, and 0–15per cent for Na, Fe, Ca, Mn, Cl, Mg, S and dry matter. Redistributionfrom the mother corm and vegetative organs could have suppliedthe replacement corm, cormlets and fruits with 32–53 percent of their S, K, P, N, Cu and Zn, and 11–25 per centof their Ca, Cl, Mn, Mg and dry matter. The mature replacementcorm had over 60 per cent of the plant's N and P, 25–50per cent of its dry matter, Zn, Cu, Mg, K and Cl, but less than20 per cent of its Ca, Na, Fe and Mn. Each plant produced anaverage of 12 cormlets; these had 35 per cent of the dry matterand 23–47 per cent of the amount of a particular nutrientin the new season's corms. Fruits had less than 16 per centof the dry matter and each mineral in the mature plant. Ratesof mineral intake by Ixia were much lower than reported forcrop plants, and may be related to the long growing season ofthe species. Ixia polystachya L., corm, nutrition, mineral nutrients, nutrient redistribution     

An analysis of the growth response of carrot seedlings to deficiency in some mineral nutrients

Critical plant concentrations for a reduction in relative growth rate to 90% of that of fully nourished plants were estimated by a novel method for several mineral nutrients. Carrot plants were grown from seed for 28 days in a range of nutrient solutions omitting N, P, K, Ca, S, Mg, Fe, B, Mn, Zn, Cu and Mo as separate treatments. All treatments except -Mn, -Zn, -Cu and -Mo resulted in effects on plant growth and the development of deficiency symptoms. Estimates of critical concentrations were based on a simple simulation model incorporating the principle of nutrient dilution with increasing plant weight and on mineral analysis of the plants. Parameters governing the shape of the relationship between fractional relative growth rate and plant nutrient concentration were altered until the model predicted the observed final mean dry weight of deficient plants and time of divergence of this growth curve from that of fully nourished plants. Critical concentrations so obtained were higher than those previously reported for Ca, Fe, N and P in carrots and lower for K, Mg and S.     

Phylogenetic variation in the shoot mineral concentration of angiosperms

The calcium (Ca) concentration of plant shoot tissues varies systematically between angiosperm orders. The phylogenetic variation in the shoot concentration of other mineral nutrients has not yet been described at an ordinal level. The aims of this study were (1) to quantify the shoot mineral concentration of different angiosperm orders, (2) to partition the phylogenetic variation in shoot mineral concentration between and within orders, (3) to determine if the shoot concentration of different minerals are correlated across angiosperm species, and (4) to compare experimental data with published ecological survey data on 81 species sampled from their natural habitats. Species, selected pro rata from different angiosperm orders, were grown in a hydroponic system under a constant external nutrient regime. Shoots of 117 species were sampled during vegetative growth. Significant variation in shoot carbon (C), calcium (Ca), potassium (K), and magnesium (Mg) concentration occurred between angiosperm orders. There was no evidence for systematic differences in shoot phosphorus (P) or organic-nitrogen (N) concentration between orders. At a species level, there were strong positive correlations between shoot Ca and Mg concentration, between shoot P and organic-N concentration, and between shoot K concentration and shoot fresh weight:dry weight ratio. Shoot C and cation concentration correlated negatively at a species level. Species within the Poales and the Caryophyllales had distinct shoot mineralogies in both the designed experiment and in the ecological survey.     

Redistribution of Nutrient Elements from Cotyledons of Two Species of Annual Legumes During Germination and Seedling Growth

The distribution of dry matter and various mineral nutrientsbetween testa and embryo of seeds of Lupinus albus and L. angustifoliusis described It was found that lupin seeds at either end ofa pod contained less dry matter and minerals than seeds in themiddle of the fruit. The transport of dry matter, N, P, K, S,Ca, Mg, Na, Fe, Zn, Mn and Cu from cotyledons of parent seedsof both species to the seedling axis was measured from germinationto the time of cotyledon death. N, P, K and S were retrievedfrom cotyledons with over 90 per cent efficiency, dry matter,Mg, Na, Fe, Zn, Mn and with 59–90 per cent efficiency,and Ca with 26–31 per cent efficiency. There was littlechange in the efficiency of nutrient retrieval from cotyledonswhen seedlings were grown in different culture media. Both speciesshowed a linear relationship between the loss of each elementand dry matter throughout the experiment, and a similar proportioningbetween root and shoot of the amount of a specific nutrientmobilized from cotyledons of parent seeds. Lupinus albus L., Lupinus angustifolius L., lupin, transport, of dry matter and mineral nutrients     

Seasonal Dynamics of the Accumulation, Distribution and Redistribution of Dry Matter and Mineral Nutrients in a Weedy Species of Gladiolus (Gladiolus caryophyllaceus)

The seasonal dynamics of the accumulation, distribution andredistribution of dry matter and 12 mineral nutrients by a weedyspecies of gladiolus (Gladiolus caryophyllaceus) were studiedat Perth, Western Australia, where it has colonized the nutrient-poorsandy soils. Parent corms sprouted in autumn, and the plantshad completed their growth cycle by early summer. The maturereplacement corm had 15-25% of the plant's P, Ca, Na, Zn andCu, 5-15% of its K, N, Cl, Mg, S and dry matter, and < 5%of its Fe and Mn. Seeds had 26% of the plant's dry matter, 60%of its N and P, 21-33% of its S, Mg, Cu and K, 5-20% of itsFe, Mn and Zn, and < 5% of its Ca and Na. The mature vegetativeshoot had 47% of the plant's dry matter and over 40% of eachnutrient, except for N, P and Cu. Phosphorus, K and N were redistributedfrom the parent corm with over 85% efficiency, S, Mg, Zn andCu with 60-70% efficiency, but there was < 10% redistributionof Ca, Na, Cl, Fe and Mn. The efficiency of redistribution fromthe leafy shoot was over 70% for N and P, 29-52% for K, Mg andCu, 16-20% for S, Zn and Cl, but negligible for Ca, Na, Fe andMn. Redistribution from the shoot could have provided the replacementcorm and seeds with 53-98% of their Cu, Mg, N, P and K, and29-38% of their S, Zn and dry matter. Seeds contained over 60%of each nutrient in a capsule, except for Ca, Na and Fe. Redistributionfrom the capsule walls could have provided 13-19% of the P,Cu and Zn, and 3-7% of the N, K, Mg and dry matter accumulatedby seeds. Each plant produced an average of 520 seeds. Removalof flowers and buds at first anthesis resulted in a larger replacementcorm containing a greater quantity of most nutrients, indicatingcompetition between the replacement corm and seeds for nutrients.Redistribution from parent to replacement cormlets in the absenceof shoot and root development was high, with over 50% of thedry matter and each nutrient, except for Ca, being transferred.Concentration of nutrients were low in all organs of G. caryophyllaceus,especially the replacement corm. It was concluded that the effectiveredistribution of key nutrients, such as N and P, to reproductivestructures and tolerance of low internal concentrations of nutrientscontribute to the capacity of G. caryophyllaceus to colonizeand persist on infertile soils.Copyright 1993, 1999 AcademicPress Gladiolus caryophyllaceus, corm, distribution, dry matter, gladiolus, mineral nutrients, nutrient accumulation, nutrient redistribution, seasonal growth, weed     

DEVELOPMENTAL CHANGES IN ENERGY (ATP AND ADP) AND NUTRIENT LEVELS PRIOR TO SENESCENCE IN PODDED AND DEPODDED PEA PLANTS

Energy (ATP and ADP) levels in stem apices of depodded pea plants (Pisum sativum L. cv. Little Marvel) were significantly higher than those of podded plants during the pod-filling stage before whole plant senescence. This difference in energy content appeared before decreases in leaf chlorophyll and soluble proteins occurred in plants of both treatments. In contrast, the mineral nutrient levels (N, P, K, Ca, Mg, Fe, and Mn) in stem apices of plants from both treatments were similar. Energy levels in reproductive leaves from podded and depodded plants were similar. The mineral nutrients in leaves with fruits in their axils and similar leaves of depodded plants were comparable except for nitrogen. Plant growth measurements—dry weight, leaf area, leaf dry weight, root/shoot ratio—were significantly higher in depodded than podded plants. Whole plant senescence occurred significantly earlier in podded than in depodded pea plants.     

Growth and shoot: root ratio of seedlings in relation to nutrient availability

The influence of mineral nutrient availability, light intensity and CO₂ on growth and shoot:root ratio in young plants is reviewed. Special emphasis in this evaluation is given to data from laboratory experiments with small Betula pendula plants, in which the concept of steady-state nutrition has been applied.Three distinctly different dry matter allocation patterns were observed when growth was limited by the availability of mineral nutrients: 1, Root growth was favoured when N, P or S were the major growth constraints. 2, The opposite pattern obtained when K, Mg and Mn restricted growth. 3, Shortage of Ca, Fe and Zn had almost no effect on the shoot:root ratio. The light regime had no effect on dry matter allocation except at very low photon flux densities (< 6.5 mol m^-2 day^-1), in which a small decrease in the root fraction was observed. Shortage of CO₂, on the other hand, strongly decreased root development, while an increase of the atmospheric CO₂ concentration had no influence on dry matter partitioning. An increased allocation of dry matter to below-ground parts was associated with an increased amount of starch in the tissues. Depletion of the carbohydrate stores occurred under all conditions in which root development was inhibited. It is concluded that the internal balance between labile nitrogen and carbon in the root and the shoot system determines how dry matter is being partitioned in the plant. The consistency of this statement with literature data and existing models for shoot:root regulation is examined.     

外源NO对缺镁胁迫下玉米幼苗生长和离子平衡的影响

研究了在缺镁胁迫下,外源NO对缺镁玉米幼苗生长、根系活力和离子含量的影响。结果表明,缺镁胁迫使玉米幼苗株高、根长和干鲜重下降,根系活力降低,N元素在地上部和根部分配失调,新叶和老叶中Mg2＋、Cu2＋、Fe3＋、Mn2＋等离子含量下降,Ca2＋、K＋、Zn2＋等离子含量上升。根中Mg2＋离子含量下降,Ca2＋、K＋、Zn2＋、Cu2＋、Fe3＋、Mn2＋等离子含量上升。用100μmol·L-1一氧化氮供体硝普钠（SNP）处理后,玉米幼苗株高、根长、干重和鲜重均提高,根系活力增强,改善了N代谢,新叶中Ca2＋、K＋和Zn2＋等离子含量下降,Mg2＋、Cu2＋、Fe3＋和Mn2＋等离子含量提高,老叶中Mg2＋、Ca2＋、K＋和Zn2＋等离子含量下降,Cu2＋、Fe3＋和Mn2＋等离子含量提高,根中Mg2＋、Ca2＋、K＋、Cu2＋、Zn2＋、Fe3＋和Mn2＋离子含量均下降。实验结果表明,NO保护玉米幼苗免受缺镁胁迫的影响。     

盐土和沙土对新疆常见一年生盐生植物生长和体内矿质组成的影响

选用古尔班通古特沙漠南缘荒漠-绿洲交错带常见的一年生盐生植物盐角草、刺毛碱蓬、叉毛蓬、猪毛菜和碱地肤为材料,比较了它们在原状盐土和沙土中的生长及体内矿质元素组成的差异。结果表明：① 原状盐土0—100 cm各土层的pH值低于沙土,但电导率和含水量明显高于沙土;② 原状盐土中生长的植物干重是沙土中生长植物干重的7—118倍,后者的根冠比是前者的2—6倍。③ 体现肉质化程度的地上部含水率为52%—81%,中低耐盐植物含水率在两种土壤中差异显著,强耐盐植物差异不显著;④ 5种一年生盐生植物地上部氮浓度为11—34 g/kg,在有效氮含量高的盐土上植物氮浓度也高;磷浓度为1—4 g/kg,在有效磷高的盐土上植物磷浓度也较高（盐角草除外）;但沙土中的植物地上部钾浓度明显高于盐土中植株的地上部钾浓度,这与两种土壤在0—60 cm土层中的钾浓度差异相反;⑤ 尽管原状盐土0—100 cm土层中的水溶性钙、镁、钠、氯、硫浓度显著高于沙土,盐土与沙土中生长的植物地上部钠、水溶性氯和硫的浓度比值远远低于土壤中的相应元素浓度的比值,甚至盐土中的植株钙、镁浓度等于或显著低于沙土中生长的植物。表明盐土不仅影响一年生盐生植物的生长,也显著影响这些植物对矿质元素的吸收和累积。一年生盐生植物能够选择性吸收不同生境中的矿质元素。本研究期望为进一步深入研究盐生植物耐盐的适应机制提供依据,也可为植物修复盐碱土的品种选择提供参考。     

Influence of soil oxygen and soil water on the accumulation of nutrients in avocado seedlings (Persea Americana mill.)

Summary This experiment was conducted in a greenhouse to study the influence of 2 soil-oxygen levels and 4 irrigation levels on the plant response, root decay, concentrations of 12 nutrients, as well as on total amounts of nutrients per avocado seedling (Persea americana Mill.).Reduced soil-oxygen supply to the roots significantly reduced the amount of dry weight per seedling, increased percentage of root decay, and reduced the concentrations of N, P, K, Ca, Mg, and B in the tops, while Na and Fe were increased. Concentrations of K, Mg, Na, and Cl in the roots were decreased, while N and Ca were increased with decreased soil oxygen supply to the roots. Total amounts of N, P, Ca, Mg, Na, and Cl per seedling were decreased with the low soil-oxygen supply to the roots.Only slight differences in dry weight of the tops of seedlings were found. The highest degree of root decay was caused by the irrigation treatment where a water table was present. In the tops, concentrations of N, P, K, Mg, Na, Zn, Cu, Mn, B, and Fe were significantly influenced by differential irrigation treatments; in the roots, concentrations of P, K, Ca, Mg, Na, and Cl were also significantly influenced; and total amounts of N, P, Mg, and Cl the whole seedling were likewise significantly influenced.Significant interactions were noted between the soil-oxygen and irrigation treatments on the dry weight of tops, roots, and total amounts of dry weight produced per seedling. The lowest amount of dry weight of roots and the highest degree of root decay were found in the avocado seedlings grown under low soil-oxygen supply and the irrigation treatment where a water table was present. Several significant interactions between soil oxygen and irrigation on the concentrations of N, P, K, Ca, Zn, and Mn are discussed.University of California, Citrus Research Center and Agricultural Experiment Station, Riverside, California. The research reported in this paper was supported in part by NSF Grant GB-5753x.     

Partitioning of shoot and root dry matter and carbohydrates in bean plants suffering from phosphorus, potassium and magnesium deficiency

The influence of varied supply of phosphorus (10 and 250 mmolP m^–3) potassium (50 and 2010 mmol K m^–3) and magnesium(20 and 1000 mmol Mg m^–3) on the partitioning of dry matterand carbohydrates (reducing sugars, sucrose and starch) betweenshoots and roots was studied in bean (Phaseolus vulgaris) plantsgrown in nutrient solution over a 12 d period. Shoot and rootgrowth were quite differently affected by low supply of P, K,and Mg. The shoot/root dry weight ratios were 4.9 in the control(sufficient plants), 1.8 in P-deficient, 6.9 in K-deficientand 10.2 in Mg-deficient plants. In primary (source) leaves,but not in trifoliate leaves, concentrations of reducing sugars,sucrose and starch were also differently affected by low nutrientsupply. In primary leaves under K deficiency and, particularlyMg deficiency, the concentrations of sucrose and reducing sugarswere much higher than in control and P-deficient plants. Magnesiumdeficiency also distinctly increased the starch concentrationin the primary leaves. In contrast, in roots, the lowest concenfrationsof sucrose, reducing sugars and starch were found in Mg-deficientplants, whereas the concentrations of sucrose and starch wereparticularly high in P-deficient plants. There was a close relationshipbetween shoot/root dry weight ratios and relative distributionof total carbohydrates (sugars and starch) in shoot and roots.Of the total amounts of carbohyd rates per plant, the followingproportions were parti tioned to the roots: 22.7% in P-deficient,15.7% in control, 3.4% in K-deficient and 0.8% in Mg-deficientplants. The results indicate a distinct role of Mg and K in the exportof photosynthates from leaves to roots and suggest that alterationin photosynthate partitioning plays a major role in the differencesin dry matter distribution between shoots and roots of plantssuffering from mineral nutrient deficiency. Key words: Bean, carbohydrates, magnesium nutrition, phosphorus nutrition, potassium nutrition, shoot/root growth     

Relationships between shoot to root ratio, growth and leaf soluble protein concentration of Pisum sativum, Phaseolus vulgaris and Triticum aestivum under different nutrient deficiencies

Relations between shoot to root dry weight ratio (S : R), total plant dry weight (DW), shoot and plant N concentration and leaf soluble protein concentration were examined for pea ( Pisum sativum L.), common bean ( Phaseolus vulgaris L.) and wheat ( Triticum aestivum L.) under different nutrient deficiencies. A regression model incorporating leaf soluble protein concentration and plant DW could explain greater than 80% of the variation in S : R within and between treatments for pea supplied different concentrations of NO₃^– or NH₄⁺ in solid substrate; pea and bean supplied different concentrations of N, P, K and Mg in liquid culture; and wheat supplied different concentrations of N, P, K, Mg, Ca and S in liquid culture. Addition of shoot or plant N concentration to the model explained little more of the variation in S : R. It is concluded that results are consistent with the proposal that macronutrient effects on S : R are primarily mediated through their effects on protein synthesis and growth.     

圆柏属常绿木本植物元素含量的季节动态

测定分析了圆柏属2种常绿木本植物叶片干物质含量、叶绿素含量及N、P、K、Na、Ca、Mg等元素含量的季节变化和元素间的关系。结果发现,两种圆柏叶片N含量与叶绿素含量正相关,反映了其一年四季的生长情况;两树种N和K含量的季节变化趋势相似,夏、秋季高于冬、春季,表明两树种夏、秋季富集的营养物质较多,与夏、秋季较高的生物量一致;而P、Ca、Mg和Na含量是冬、春季较夏、秋季高,表明圆柏属植物通过积累这些无机渗透调节剂来增强其对低温的抗性。两树种叶片对N和K同步积累,对P、Na和Mg同步积累,但在元素积累模式上也存在一定的差异,元素间的关系也要复杂得多。     

Variations in the Mineral Composition of Herbarium Plant Species Collected During the Last Three Centuries

Mineral content (dry weight basis) was determined for herbariumspecimens of 12 C₃ plants (trees, shrubs and herbs) collectedduring the last 250 years in N.E. Spain. Present values of Al,Ca, Cu, Sr, Fe, P, Mg, Mn, K, Na, S, and Zn were always lowerthan in any other period of the last three centuries. Only oneC₄ plant was analysed. It presented a similar pattern to theC₃ plants. These results are in accordance with experimentalresults that have shown that the mineral content of plants grownin elevated CO₂ is generally lowered. Increased atmosphericCO₂ and other anthropogenic environmental changes are suggestedas possible causes of the changes in mineral content. Key words: Leaf mineral content, Al, Ca, Cu, Sr, Fe, P, Mg, Mn, K, Na, S, Zn, herbaria, last three centuries     

Santalum album: Kernel Composition, Morphological and Nutrient Characteristics of Pre-parasitic Seedlings under Various Nutrient Regimes

Omission of all nutrients or individual minerals (N, K, P, S,Ca) from the growth medium of pre-parasiticSantalum album seedlingsproduced significant morphological effects. Compared with fullyfertilized seedlings, shoot and root length, leaf area, leaflength and width, leaf number, internode length, shoot length/rootlength ratio, chlorophyll levels, fresh mass and dry mass wereall reduced; leaf thickness increased and stomatal numbers,petiole lengths, root lengths and haustorial numbers showedvariable but significant responses. Mineral-specific deficiencysymptoms were evident in all omission treatments after 3 months.Treatments in which N, K or all minerals were omitted had thegreatest dwarfing effect and increase in height and leaf numberceased after 3 months: only seedlings with no added nutrients(dependent on kernel nutrition) were healthy. The mineral contentof no-nutrient seedlings approximated that in kernels. The distributionof minerals between plant parts for each treatment is given.K concentrations and K/Ca ratios were relatively high in leavesof seedlings which received treatments containing K, especiallywhen Ca was absent. A high K/Ca ratio may be inherent inS. albumseedlings rather than acquired after subsequent host connection.All fully fertilized seedlings developed haustoria within 3months suggesting readiness for early host attachment. Seedlingsin no-nutrient, no-N, no-K or no-P treatments had fewer haustoria. Santalum album ; Indian sandalwood; sandalwood kernels; sandalwood seedlings; nutrient omission; healthy characteristics; deficiency characteristics     

Effects of varied soil nitrogen supply on Norway spruce (Picea abies [L.] Karst.)

During a seven-month period the effect of different nitrogen (N) availability in soil on growth and nutrient uptake was studied in three-year-old Norway spruce (Picea abies [L.] Karst.) trees. The plants were grown in pots on N-poor forest soil supplied with various amounts and forms (inorganic and organic) of N. Increasing supply of inorganic N (as NH₄NO₃) increased the formation of new shoots and shoot dry weight. The root/shoot dry weight ratio of new growth was drastically decreased from 1.6 in plants without N supply to 0.5 in plants supplied with high levels of NH₄NO₃. This decrease in root/shoot dry weight ratio was associated with distinct changes in root morphology in favour of shorter and thicker roots. The addition of keratin as organic N source did neither affect growth nor root morphology of the trees. The amount of N taken up by plants was closely related to the supply of inorganic N, and trees supplied with highest levels of NH₄NO₃ also had the highest N contents in the dry matter of needles and roots. In contrast, N contents in needles of trees grown without additional N, or with keratin supply, were in the deficiency range. Supply of NH₄NO₃ decreased the contents of phosphate (P) and potassium (K) and therefore markedly increased N/P and N/K ratios in the needles. On the other hand, the contents of calcium (Ca), magnesium (Mg), and manganese (Mn) in the needles were increased in the plants supplied with inorganic N, suggesting high soil availability and promotion of uptake of these divalent cations by high nitrate uptake. The observed effects on root/shoot dry weight ratio, root morphology, and mineral nutrient composition of the needles indicated that high inorganic N supply may increase above-ground productivity but at the same time decrease the tolerance of trees against soil-borne (e.g. deficiency of other mineral nutrients) stress factors. Deceased 21 September 1996 Deceased 21 September 1996     

Slash pine seedling response to potassium and calcium on imperfectly drained coastal plain soil

In a greenhouse study, increases in dry weight and N, P, K, Ca, and Mg content of seedlings from a preplanting application of 0.16 meq K/100 g of Caddo silt loam topsoil were markedly greater on soil containing 0.06 meq K, than on soil containing 0.09 meq K/100 g. Except for further increasing K and reducing Ca content of seedlings, applications of 0.32 and 0.48 meq K/100 g added little to growth or nutrient accumulation. Additions of 1 to 5 meq Ca/100 g either did not affect or slightly reduce dry weight and uptake of all nutrients except Ca. Potassium and calcium treatments did not interact to influence growth or nutrient uptake. Dry weight and accumulation of N, P, and K were all associated with the amount of K available; Ca accumulation was related only to available Ca.     

Growth and Nutrient Uptake by Barley (Hordeum vulgare L. cv Herta): Studies Using an N-(2-Hydroxyethyl)ethylenedinitrilotriacetic Acid-Buffered Nutrient Solution Technique (I. Zinc Ion Requirements)

The critical range of Zn2+ activity in nutrient solution required for optimum growth of barley (Hordeum vulgare L. cv Herta) was studied using the synthetic chelating agent N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid to buffer micronutrient metal ions. The activity of Zn2+ was varied over a wide range from approximately 0.1 x 10-11 to 22 x 10-11 M Zn2+. The dry weight of barley shoots reached a maximum at Zn2+ activities above approximately 3 x 10-11 M and was clearly depressed when Zn2+ activities were below about 1 x 10-11 M. The relationship in shoots between dry weight and Zn concentrations supports the view that there is a critical Zn concentration of about 25 [mu]g g-1 dry weight in whole shoots of barley seedlings. When Zn2+ activities in solution were near or below approximately 3 x 10-11 M, barley shoots accumulated higher concentrations of P, Mn, Ca, Mg, and Na, whereas Cu concentrations were reduced. P and Mn began to accumulate in the shoots before differences in dry weights were apparent and provided the earliest index of Zn deficiency. In Zn-deficient roots, concentrations of Ca and Mg increased by 25 to 30%, and those of Fe and Mn more than doubled. Zn appears to play a special role in regulating uptake of several mineral nutrients in barley.