Growth response of cabbage plants to lithium,sodium, and rubidium under water culture conditions

Cabbage (B. oleracea L. var. capitata L.) plants wore grown for 79 days in cuture solutions obtaining 4 levels of lithium, 0, 0.1, 1. 10 mel) sodium (0, 0.2. 2, 20, or rubidium , 0, 0.05, 0.5) combined with a low or high supply of potassium(0.2 or 2 mcf/l, and the effects of the cations supplied on the growth and ration composition of the plants were studied.

The total dry weight of the plants decreased at higher levels of the cations, especially Li in the culture solution, concurrent with an increaie in the contents of each cation in the plants. The decrease in the dry weight at higher levels was smaller in the high K supply, than in the low supply, causing a decrease in the contents of the cations. The critical contents of Li, Na, and which resulted in a 50° decrease in the dry weight or inner leaves due to excess injury were estimated to be about 0.07, 2.5, and 3.0% on a dry basis in the outer leaves and 0.05, 2.0, and 3.0% in the roots, respectively, regardless of the K supply.     

Growth response of cabbage plants to transition elements under water culture conditions

Cabbage plants were water-cultured under 4 levels of titanium (0,0,4,4,20 ppm), vanadium (0, 0.4,4, 20 ppm), chromium (0, 0.2, 2, 10 ppm), manganese (0, 0.4, 4, 20 ppm), and iron (0, 1, 10, 50 ppm), and the effects of the elements supplied on the growth of the plants and on the distribution of the elements in the plants were studied.

The dry weight of a whole plant and of inner leaves (yield) without the addition of Ti, V, and Cr did not decrease, while that without the addition of Mn and Fe decreased slightly. The addition of Ti, V, Cr, Mn, and Fe (more than 0.4, 0.4, 2, 4, and 10 ppm, respectively) decreased the yield. Slight transition element-induced chlorosis was observed in the plots at high levels of Ti, Cr, and Mn.

The contents of the elements in the plants increased with an increase in the concentration of each element in the culture solution. The critical contents of Mn and Fe in plant-tops which resulted in a slight decrease in the yield due to the deficient injury were estimated to be about 10 and l00 ppm. The contents of Ti, V, Cr, Mn, and Fe when the yield decreased by 50% due to the excess injury were 4,6, 20, 3,000, and 300 ppm in outer leaves and 3,000, l,000, 2,000, 15,000, and 50,000 ppm in roots, respectively.     

The role of macronutrients in cabbage-head formation

Abstract

Cabbage plants were grown at graded levels of nitrogen supply and light intensity, and the combined effects on cabbage-head development were studied during the spring and autumn seasons.

The cabbage-head yield (i.e. dry weight of inner head leaves) was the highest at 50 ppm N in the nutrient solution, followed by 500 and 5 ppm N at full light intensity, and decreased with decrease in the, light intensity by shading. The decrease in cabbage-head yield caused by the shading was greater at high nitrogen levels during the autumn (low solar energy) season than during the spring (high solar energy) season. As the nitrogen supply increased or the light intensity decreased during both the spring and autumn seasons, nitrogen, especially soluble N, accumulated and the carbohydrate (sugar and starch) content decreased in the plants. Cabbage-head development occurred efficiently when the total N content in the outer leaves remained at about 2–3% and the carbohydrate production was large at full light intensity.     

Some effects of fly ash (from coal burning) on bush bean plants grown in solution culture

Abstract

Bush bean plants (Phaseolus vulgaris L. C. V. Improved Tendergreen) were grown for 14 days in 3700‐ml solution cultures with varying application rates of fly ash from a coal burning plant in California. Plants were also grown in a solution culture experiment in the presence of tiie chelating agent DTPA (diethylene triamine pentaacetic acid) and also in solutions acidified with HCl. The latter treatments were to determine if metals in the fly ash could be made more available to plants. The higher levels of fly ash (5 to 10 g/3700 ml) resulted in increased Ca, B, Si, Sr, and Ba in leaves, stems, and roots. No plants, however, appeared to have an excess of trace metals. In another experiment DTPA and HCl amendments failed to increase greatly the availability of trace metals from the fly ash in solution culture except for Zn. In this experiment the fly ash was the sole source of Ca and plants were deficient in Ca because insufficient fly ash was added. The fly ash resulted in increased Zn, Ca, Fe, Mn, B, Al, Si, Ti, Mo, Li, Sr, Ba in leaves, stems, and roots and increased V, Co, and Ni in roots. There was 3 to 4 μg/g Sn and 0.6 μg/g Be in the roots of plants grown with fly ash. In another experiment, fly ash supplied all the Ca necessary for plant growth without decreased yields resulting from any trace metal.     

Zinc toxicity‐induced variation of mineral element composition in hydroponically grown bush bean plants

Bush bean plants (Phaseolus vulgaris L. cv Contender) were grown for twenty days in nutrient solution (pH=5), containing 0.13, 0.3, 0.5 or 0.75 mg 1^‐1 Zn as ZnSO₄‐7H₂O. The plant yield decreased linearly with the increase of the Zn concentration supplied. The phytotoxic threshold content (for 10% growth reduction) was about 486, 242, 95 and 134^‐ μg Zn g^‐1 for roots, steins, mature primary and trifoliate leaves, and developing leaves, respectively. High inverse correlation coefficients with the Zh concentration supplied were found for the Mn content of all organs, for the P content of roots, and for the Cu and Ca contents of developing leaves. Significant positive relations were found for the Fe, Zn and Cu contents in roots and for the Zn con‐ tents in stems and fully expanded leaves. The ratios of the mineral contents between organs suggest inhibition of uptake of Mn and P, and inhibition of translocation of Fe, Cu and Ca. The relation between dry weight decrease and Zn‐induced nutrient content disorders were discussed.     

The response of okra to molybdenum in sandculture

Abstract

The role of molybdenum in plant growth was examined by growing ‘Emerald’ okra (Abelmoschus esculentus L. Moench) to fruiting in sand‐culture.

Molybdenum treatment lower than 1 ppm, resulted in leaves that were generally pale yellow and curled upwards. At 1 ppm and 4 ppm Mo, plants were generally healthy with deep green leaves, while Mo application at 6 and 16 ppm resulted in stunted plant growth, deep green leaves, and dark brownish coating on the roots. Shoot/root ratio decreased with increasing rates of Mo. Total chlorophyll was unaffected by Mo application, whereas plant dry matter production and fruit yield were depressed at the 16 ppm Mo treatment.

Leaves of plants receiving less than 1 ppm Mo had higher concentrations of NO₃‐N, P, K, Ca and Mg than plants receiving above 1 ppm Mo treatments. The reverse was the case with the micronutrient levels. Specifically, Mo treatments higher than 1 ppm increased leaf‐Mo, ‐Fe, Mn and Zn and root‐Mo and Mn. The highest percentage of Fe and Mn, accumulated in the leaves, followed by the root and least in the wood, whereas the roots had the highest percentage of accumulated Mo, Cu and Zn. Leaf‐Mo was positively correlated with leaf‐Fe and Mn and root‐Mo and Mn. Molybdenum deficiency symptoms appeared in plants with leaf‐Mo of 5 ppm and treated with less than 1 ppm Mo. The 2 ppm Mo treatment with leaf‐Mo of 18 ppm produced normal and healthy plants, whereas. Mo application from 8 to 16 ppm with corresponding leaf‐Mo of 42 and 90 ppm Ho respectively produced plants that were severely stunted and had generally poor growth. The relatively high Ho concentration observed suggests that the okra plant is a Mo accumulator.     

Manganese toxicity in tomato plants: Effects on cation uptake and distribution

Two experiments are described in which tomato plants (Lycopersicon esculentum L. var Ailsa Craig) were grown in water culture supplied with 10–300 μM Mn. Toxicity symptoms associated with a yield reduction were observed only in treatments in excess of 50 μM Mn indicating that this species is relatively tolerant of high Mn supply. Dark brown/black spots appeared first in the cotyledons. Similar symptoms were observed in the leaves, progressively from the oldest leaf. Manganese concentration in the shoot tissues ranged from 286 to 4240 μg. g^‐1 dry weight. The high Mn concentration values found in the shoot tissues of the toxic plants indicate that Mn was highly mobile in the xylem as confirmed by xylem sap analysis.

The concentrations of both Ca and Mg were lower in the smaller Mn toxic plants. Not only was uptake of Ca and Mg retarded but so also was the distribution of Ca and Mg to the younger tissues as illustrated by measurements of Ca and Mg concentrations along a leaf age sequence. This is in accord with the cation‐anion balance of the xylem exudates collected from decapitated plants.

Higher cation exchange capacity (CEC) was found in the leaf tissues of toxic plants particularly in the older leaves but similar values of C.E.C were recorded for the younger leaf tissues of both control and toxic plants.     

Diagnostic indices of zinc deficiency in tropical legumes

The effect of 0.005 ppm, 0.01 ppm, 0.05 ppm and 0.10 ppm zinc on the growth and chemical composition of Desmodium uncinatum Jacq. cv. Silverleaf; Macroptilium lathyroides L.; Lablab purpureus; and Glycine max. L. cv. Wills were studied in solution culture in a controlled environment room.

Dry matter production of tops of all species was reduced at the lower zinc treatments while that of roots was unaffected by zinc supply.

Zinc concentrations of leaves from three plant positions did not provide a reliable index of zinc nutrition. The lowest zinc treatments often produced greater leaf concentrations of zinc than did higher zinc treatments. The cytoplasmic fractions of the leaf tissue contained the highest zinc concentrations. Cell walls, nuclei, chloroplasts and mitochondria contained extremely low concentrations, and the data were generally variable, reflecting the poor reproducibility of the techniques used.

Phosphorus concentrations in leaves were generally increased at the low zinc treatments, an effect not entirely attributable to the reduction in dry matter production. The proportion of inorganic phosphorus increased and that of organic phosphorus decreased at the lower zinc treatments. Lipoid and residual phosphorus fractions were not affected consistently by zinc treatments.

Leaves of plants receiving the lowest zinc treatment generally had significantly lower nitrogen concentrations than those receiving the higher zinc treatments.

In another experiment, in which Glycine wightii was substituted for G. max., RN‐ase activity increased as the zinc supply was reduced and this was accompanied by a decrease in protein concentration. The data show that RN‐ase activity could be a useful diagnostic index of incipient zinc deficiency.     

Yield formation of five crop species under water shortage and differential potassium supply

A long‐term field experiment on a Haplic Phaeozem, established 1949 with four levels of potassium (K) supply (5, 69, 133, and 261 kg K ha^?1), was analyzed for the interaction between K supply and yield loss of five crop species by water shortage. The crop species were cultivated simultaneously side‐by‐side in the following rotation: potato (Solanum tuberosum L.), silage maize (Zea mays L.), spring wheat (Triticum aestivum L.), beet (Beta vulgaris L.), and spring barley (Hordeum vulgare L.). The treatment with 133 kg K ha^?1 supply had a nearly balanced K budget. In the treatments with lower supply, the soil delivered K from its mineral constituents. On the low‐K plots (especially on those with only 5 kg K ha^?1), crops suffered yield depressions of nearly all main harvest products (cereal grains, potato tubers, beet storage roots, silage maize) and by‐products (straw, beet leaves) by up to 40.7% of dry matter. Only wheat grains were an exception. Potassium concentrations in the harvested plant parts decreased nearly in parallel to the reduction of their dry matter yields, with the exception of cereal grains, which kept stable concentrations even in the treatment with only 5 kg K ha^?1. A comparison of four year‐pairs with differing levels of precipitation in yield‐relevant periods showed an average water shortage‐induced depression of dry matter yields by 19.7% in the main harvest products. The severity of this yield depression was not mitigated by elevated K supply, with the exception of beet leaves, where the dry matter production was stabilized by high K supply. In this crop, the reduction of storage‐root yield was associated with a decrease in harvest index and was therefore obviously caused by an inhibition of assimilate translocation from the leaves into these organs, in contrast to cereals, where water shortage primarily affected dry matter production in vegetative organs. It is concluded that the physiological causes of yield reduction by drought stress and the possibility of its amelioration by K supply differ between plant species and organs.     

Effects of Boron and Calcium Supply on Calcium Fractionation in Plants and Suspension Cells of Rape Cultivars with Different Boron Efficiency

Abstract

In this study, the effects of boron (B) and calcium (Ca) supply on Ca fractionation in suspension cells and different tissues of rape (Brassica napus L.) plants of two cultivars with different B efficiency were studied, with a purpose to elucidate the mechanism by which B affects Ca concentration in plants. As Ca supply increased in nutrient solution or culture medium, the relatively easily extractable Ca fractions, that is H₂O and 80% ethanol extractable Ca in leaves, 1 mol L^?1 NaCl extractable Ca in upper leaves, roots and suspension‐cell were significantly increased. While the recalcitrant Ca fractions extracted by 2% acetic acid, 0.6 mol L^?1 HCl and Ca in the residue were not affected by Ca supply. Increasing B supply in nutrient solution or culture media significantly reduced 1 mol L^?1NaCl extracted Ca in suspension cell and roots of both cultivars, which were most likely related to the alteration of cell wall metabolism. Calcium extracted by 2% acetic acid, 0.6 mol L^?1 HCl and Ca in residue in suspension‐cell and roots of B inefficient cultivar Bakow were easily improved by B deficiency as compared to that of B efficient cultivar Tezao16. Increasing of these relative recalcitrant Ca fractions was related to the different response of cultivars to the B deficiency, which may reflected different extent that Ca deposited in the two cultivars due to impaired membrane integrity under B deficiency. The effects of B on Ca concentration in lower and upper leaves of the two cultivars were quite different and were the integrated effects of B on Ca metabolism, Ca transport in plants and growth of certain organ. Increasing B supply increased total Ca concentration in upper leaves of Bakow and reduced that of Tezao16, which might relate to the different adaptability of the two cultivars to comparatively higher B supply.     

Nitrogen nutrition of white rose potato in relation to vegetative growth and mineral content of leaves and roots

Abstract

White Rose potato plants were transplanted to nutrient solutions provided vith nine treatments of Ca(NO₃)₂ ranging from 0 to 64 mmoles per liter. Eighteen days later, symptoms of N‐deficiency ranging from very severe to none vere observed. The plants at this time were harvested, and leaves were sampled, oven dried, ground, and then analysed for K, Na, Ca, Mg, NO₃‐N, and acetic acid soluble H₂PO₂‐P.

Shoot and fibrous root growth increased with nitrate supply to an optimum, and then decreased with increased nitrate supply, suggesting nitrate toxicity due to the high nitrate supply of the nutrient solution. The nitrate content of the tissues increased with increased nitrate supply. Toxicity due to excess nitrate was associated with a very high nitrate content of the leaf tissues.

The critical NO₃‐N concentration at a 10% reduction in vegetative growth due to N‐deficiency is about 2000 ppm (0.2%) on a dry basis for the petioles and about 300 ppm (0.03%) for the blades of recently matured leaves.     

Phosphorus,potassium and calcium concentration limits in bean plants grown under deficiency after a period of sufficiency

Bush bean plants (Phaseolus vulgaris L. cv Tacacarigua) were grown under deficient P, K or Ca nutrient solutions after seven days in sufficiency and relative growth rate, root weight ratio, specific leaf area, leaf area development and nutrient concentration profiles in the dry matter of succesive leaves, analyzed throughout ontogeny. Acute Deficiency Concentration Limits (ADCL) were defined for P (0.14%) and K (1.20%) as the concentration in the leaves able to sustain a state of marginal growth, and may indicate the physiological condition in which restoration of optimal supply may not be followed by a recovery of the plants. The continuation of growth, dry matter dilution and retranslocation within the plant are suggested as major determinants of ADCL.     

Aluminum-induced growth stimulation in relation to calcium,magnesium, and silicate nutrition in Melastoma malabathricum L.

Effects of Al, Ca, Mg, and Si on the growth and mineral accumulation of M. malabathricum (Melastoma malabathricum L.), which is an Al accumulator plant, were investigated using the water culture method. Rice (Oryza sativa L.) and barley (Hordeum vulgare L.) were used as control plants. After Al application, growth was inhibited in barley, but stimulated in M. malabathricum and rice. The growth of M. malabathricum was not reduced by very low Ca and Mg concentrations (0.1 mm Ca and 0.05 mm Mg). However, it was depressed in the absence of Ca. Ca and Mg contents somewhat decreased by Al application, which was most evident in young leaves and roots. M. malabathricum accumulated more than 10,000 mg kg^-1 Al in mature leaves, and more than 7,000 mg kg^-1 even in the youngest leaf. Al content in leaves of M. malabathricum did not decrease by the Ca or Mg application, but slightly decreased by in the absence of Ca.

Although Si is a strong ligand of Al in solution, in M. malabathricum, Si application hardly affected the growth, Al accumulation and nutrient uptake.     

Microdistribution of aluminum and manganese in the tea leaf tissues as revealed by X‐ray microanalyzer

Abstract

Tea plants (Thea sinensis L.) were found to accumulate large amount of Al (4457 ppm, D.W.) in their old leaves. The results showed that Mn stimulated the Al uptake and increased the Al content in the leaves. High concentrations of Ca and Mg in the soils decreased the Al and Mn and increased the Ca and Mg contents in the leaves. No phosphorus and aluminum interaction was found in the leaves of tea plants.

Microdistribution patterns of Al and Mn in the tea leaf tissues were also studied by means of a wavelength dispersive type X‐ray microanalyzer in conjunction with cryostage. The results of X‐ray micrographs showed that Al was densely deposited on the cell walls of the adaxial epidermis and palisade parenchyma cells of the old leaf tissues, and this distribution pattern of Al was different than that of Mn which was found mostly concentrated in the epidermal cells.     

Growth and Physiological Changes in Bitter-Gourd Plants Grown with Variable Calcium Supply in Sand Culture

Bitter-gourd (Momordica charantia L.) cv. ‘Jhallari’ plants were grown in refined sand at graded levels of calcium (Ca) supply ranging from acute deficiency (0.02 mM) to excess (8 mM). Apart from the production of characteristic visible symptoms of the respective stresses, deficient (< 4 mM) or excess (8mM) supply of Ca restricted plant biomass and fruit yield. In leaves, the concentration of chlorophyll, Hill reaction activity and the activities of catalase, peroxidase, acid invertase, ATPase, and α-amylase were reduced, but the activity of acid phosphatase was increased by deficiency of Ca. Excess Ca (8 mM) supply significantly reduced the concentration of chlorophyll, Hill reaction activity and the activity of catalase and increased the specific activities of peroxidase, acid invertase, ATPase, α -amylase, and acid phosphatase. Tissue concentration of Ca in leaves and fruits increased with increase in Ca supply from 0.02 to 8 mM. Tissue concentrations in young leaves representing the thresholds of deficiency or toxicity of Ca are found to be 1.12 and 1.98%, respectively. The critical tissue concentration in these leaves suggestive of severe deficiency of Ca is 0.85%.     

Calcium deficiency and CaCO3 on micronutrient status of plants grown in solution culture

Abstract

Plants were grown in solution culture with different levels of Ca to further evaluate Ca relationships to trace metal uptake and to toxicity of trace metals. When tomato plants (Lycopersicon esculentum L., Tropic) were grown at a low level of Ca, the Zn, Cu, Fe, Mn, Al, and Ti concentrations of leaves, stems, and roots were considerably increased. The use of an excess of CaCO₃ which increased pH did not influence the trace metal concentrations of plants any more than did Ca⁺⁺. In a factorial experiment with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen) with Ca (10^‐4,10^‐2, 10^‐2 N) and Ni (0, 2 × 10^‐6 M, 2 X10^‐5 M), Ni phytotoxicity and Ni uptake were decreased somewhat at the highest Ca level. High Ni tended to decrease the Ca concentration in leaves. High Ca and Ni both tended to decrease Fe, Cu, Zn, and Mn concentrations in leaves. The Ni had some interactions on the P concentrations of shoots.     

Physiological and biochemical responses of Melissa officinalis L. to nickel stress and the protective role of salicylic acid

The present study investigated the mediatory effects of salicylic acid (SA) in alleviating nickel (Ni) toxicity in Melissa officinalis L. One-month-old plants were exposed to different levels of Ni and SA concentrations in sand culture under greenhouse conditions. Excess Ni significantly inhibited the growth indices and dramatically increased accumulation of Ni in the leaves and roots. Exogenously SA applications (1.0 mM) led to a substantial improvement in the shoot and root fresh and dry weights. Foliar application of SA mitigated the deleterious effects of Ni and decreased its transport to the shoots. The results showed a significant loss in chlorophylls and carotenoids contents only at 500 µM of Ni. The impact of SA was not significant in terms of chlorophyll contents, while carotenoid contents of the Ni-stressed plants were significantly affected by SA. Exposure to Ni did not modify proline accumulation. Hydrogen peroxide accumulation was observed under Ni stress, while lipid peroxidation significantly decreased at the same conditions. Application of SA caused a significant decrease in electrolyte leakage of Ni-stressed plants. Due to the high potential for Ni accumulation in the roots and translocation factor values lower than 1, M. officinalis could be introduced as an excluder medicinal plant.     

Phosphorus nutrition of white rose potato in relation to growth and minerals of leaf and root tissues

Abstract

White Rose potato plants (Solanum tuberosum, L.) were grown outdoors, without tuber formation, in a modified Hoagland's nutrient solution with 9 treatments of KH₂PO₄ ranging from 0 to 4.0 mmoles per liter. Deficiency symptoms ranged from very severe to none at harvest after 27 days of growth. Growth of the potato plants increased with increased P supply and was associated with an increased P content of the plant tissues. The critical H₂PO₄‐P concentration at a 10% reduction of top growth, based on a second leaf analysis, was about 1,000 ppm for the petiole and terminal bladelet and about 1,200 ppm for the lateral bladelet, dry weight basis.

Phosphorus nutrition had only a slight effect on the K, Na, Mg and NO₃‐N concentrations of the root tissues but Ca increased as phosphate increased which suggests a calcium phosphate precipitation. Phosphorus stress lowered the K, Na, Ca, Mg and NO₃‐N concentrations of the petiole tissues of the recently matured leaf which suggests that P increases salt accumulation. Phosphorus nutrition had only a slight effect on the concentrations of K, Na, Mg and Ca of the blade tissues of the recently matured leaf but NO₃‐N increased greatly with P supply.     

Zinc nutrition affects alfalfa responses to water stress and excessive moisture

The interactive effect of applied zinc (Zn) and soil moisture on early vegetative growth of three alfalfa (lucerne) (Medicago sativa L.) varieties was investigated in a sand‐culture pot experiment to test whether there is link between Zn nutrition and soil moisture stress or excessive moisture tolerance in alfalfa plants. Three varieties (Sceptre, Pioneer L 69, and Hunterfield) with differential Zn efficiency (ability of a variety to grow and yield well in a Zn deficient soil is called a Zn‐efficient variety) were grown at two Zn levels (low Zn supply: 0.05 mg Zn kg^‐1 of soil, adequate Zn supply: 2.0 mg Zn kg^‐1 of soil) and three levels of soil moisture (soil moisture stress: 3% soil moisture on soil dry weight basis; adequate soil moisture: 12% soil moisture on soil dry weight basis; excessive soil moisture: 18% soil moisture on soil dry weight basis) in a Zn deficient (DTPA Zn: 0.06 mg kg^‐1 soil) siliceous sand. Zinc treatments were applied at planting, while soil moisture treatments were applied three weeks after planting and continued for two weeks. Plants were grown in pots under controlled temperature conditions (20°C, 12 h day length; 15°C, 12 h night cycle) in a glasshouse. Plants grown at low Zn supply developed Zn deficiency symptoms, and there was a severe solute leakage from the leaves of Zn‐deficient plants. Adequate Zn supply significantly enhanced the leaf area, leaf to stem ratio, biomass production of shoots, and roots, succulence of plants and Zn concentration in leaves. At low Zn supply, soil moisture stress and excessive moisture treatments significantly depressed the shoot dry matter, leaf area and leaf to stem ratio of alfalfa plants, while there was little impact of soil moisture treatments when supplied Zn concentration was high. The detrimental effects of soil moisture stress and excessive soil moisture under low Zn supply were less pronounced in Sceptre, a Zn‐efficient alfalfa variety compared with Hunterfield, a Zn‐inefficient variety. Results suggest that the ability of alfalfa plants to cope with water stress and excessive soil moisture during early vegetative stage was enhanced with adequate Zn nutrition.     

不同镁浓度对水稻根系生长及生理特性的影响

在温室条件下, 采用溶液培养法研究了不同Mg2+ 浓度对水稻(Oryza sativa L.)根系生长及生理特性的影响。结果表明,水稻根系干重、根冠比、总根长、Mg吸收、根系活力、伤流速度、伤流液中游离氨基酸总量和Mg含量、Mg流入速率以及Mg2+ 吸收速率与Mg2+ 供应水平密切相关。在低Mg2+ 浓度(0.05 mmol/L)条件下,水稻植株叶片在缺Mg症状出现之前分配较大比例的干物质到根系,使总根长和根冠比增加, 这可能是水稻早期对低Mg胁迫的适应机制之一。适中的Mg2+ 浓度(1.0 mmol/L)有利于水稻生长发育,促进养分吸收,提高根系活力和伤流速度以及伤流液中游离氨基酸总量。低Mg2+ 和高Mg2+ 浓度(5.0 mmol/L)在一定程度上抑制根系活力和氨基酸合成能力。植物Mg的吸收、伤流液Mg2+ 浓度、根系平均Mg流入速率和Mg2+ 吸收速率随营养液Mg2+ 浓度的增加而相应增加。