Translocation of leaf-fed 32P in pea plants as influenced by foliar and root applications of CCC and Phosfon

In controlled environment growth chambers, the effects of foliar and root applications of 2-chloroethyltrimethylammonium chloride (CCC) and 2,4-dichlorobenzyltributylphosphonium chloride (Phosfon) on the translocation of³²P fed to leaves, were investigated. When applied to leaves or to root, CCC had no effect on the relative amounts of³²P radioactivity retained by the fed leaf 5, 20 and 80 h after feeding. At 20 and 80 h after feeding, Phosfon concentrations of 0.01 and 0.1mg l^?1 reduced retention of the applied³²P. 80 h after³²P feeding, CCC concentration of 1 mg l^?1 applied as a foliar spray or to the root enhanced the downward movement of³²P. Phosfon at low concentrations, particularly at 0.1 mg l^?1, on the other hand, favoured an upward transport of the applied³²P. Foliar applications of CCC and Phosfon at high concentrations had no significant effect on³²P transport to the root and the shoot below the fed leaf, while root applications of CCC and of Phosfon inhibited downward transport. Root applications generally caused greater alterations in³²P distribution patterns than did foliar applications. On the basis of total active ingredient uptake, Phosfon was more effective than CCC in altering translocation patterns.     

The absorption and translocation of zinc-65 inPisum sativum in relation to fruit development

Summary The specificity of zinc accumulation by the first pod ofPisum sativum, variety Alaska, from the leaf in whose axil this pod is borne has been demonstrated. The secondpod receives a relatively insignificant amount of this transported zinc. The distribution pattern is somewhat similar to that previously found for phosphorus but differs in that zinc is translocated from the first bloom-node leaf 2 days prior to anthesis. At this stage no phosphorus is being translocated from this leaf. The preferential accumulation of zinc by the first pod reaches a maximum about 5 days after full bloom and the magnitude of this accumulation, relative to the aerial vegetative parts of the plant, remains essentially constant as the pod approaches maturity. The zinc accumulated by the ovules increases gradually beginning at about the 5th day after full bloom and is accompanied by a decrease in zinc retained by the carpel.Paper No. 4979, Scientific Journal Series, Minnesota Agricultural Experiment Station.     

Time dynamics of primary root branching inPisum sativum L.

Time-intervals in which the branching of primary roots occurs (the formation of lateral root primordia and the appearance of laterals on the surface of primary roots) were determined by a statistical method in several cultivars of pea. The same time-determination of the branching of the primary root in all studied cultivars was found indicating a genetic regulation of this process.     

Yield of tomato and maize in response to foliar and root applications of triacontanol

Triacontanol applied to tomato plants as a foliar spray caused a significant increase in total yield and yield per plant. When triacontantol was added to the growth medium, only a temporary increase in yield and number of fruits was observed. The yield of maize was unaffected by triacontanol, either applied to the leaves or to the growth substrate. These results support an earlier observation that a reduction in photorespiration is involved in the regulatory function of triacontanol, since only the yield of tomato, a C₃ plant, was increased. The application method was an important factor in it's effectiveness.     

Growth response of komatsuna (Brassica rapa var. peruviridis) to root and foliar applications of phosphite

Soil and hydroponic culture experiments were conducted to investigate the effects of phosphite (Phi) as phosphorus (P) fertilizer via root and foliar applications on the growth and P supply of komatsuna. In both experiments, root P treatments were combinations of Phi and phosphate (Pi) at different Pi:Phi ratios, for a total of high P level (92 mg P pot^?1; the soil experiment) or low P level (0.05 mM P; the hydroponic experiment). Foliar P treatments were deionized water (control), a Pi solution and a Phi solution at low concentration of 0.05% P₂O₅. In both experiments, shoot dry weight of plants significantly decreased as Pi:Phi ratio decreased. In the soil experiment, plants grew abnormally at a Pi:Phi ratio of 25:75 and died when P was applied to soil entirely as Phi form (0:100 treatment). In the hydroponic experiment, no visible damage was found in shoot but root growth was strongly inhibited with severe damage symptoms at low Pi:Phi ratios. Total P concentration in plant decreased significantly with decreasing Pi:Phi ratio, especially in the hydroponic experiment. Foliar application of Phi although greatly increased total P of plants compared to that of Pi in both experiments, it did not improve but further decreased plant growth at low Pi:Phi ratios in the soil experiment and at all Pi:Phi ratios in the hydroponic experiment. The results of this study clearly indicated that Phi could not be used as P fertilizer by komatsuna plants via both application methods and could not substitute P at any rate at either low or high level. No beneficial effect of Phi was detected even when it was applied at low rate or applied in combination with Pi at different ratios. The effects of Phi were strongly dependent on the P nutrition status of plants; and plants that were not sufficiently fertilized with Pi may become vulnerable to Phi even at low levels.     

Some aspects of relation between nitrogen metabolism inPisum sativum and mineral nutrition

Summary Plants ofPisum sativum grown in water culture were subjected to deficiencies in the macronutrients N, P, K, S, Ca, Mg, substitution of ammonium for nitrate and change in pH to pH 3 or 9. Free amino acids, soluble nitrogen, protein and glutamate dehydrogenase activity of shoots were measured for all nutrient types. Changes in amino acid concentrations correlated well with changes in glutamate dehydrogenase. It is considered whether this enzyme is indicative of the nutritional state of plants.     

Factors Affecting Phosphate Uptake by Aerobacter aerogenes in a System Relating Cell Numbers to 32P Uptake

The uptake of phosphate, from media limited in this ion, by resting cells of Aerobacter aerogenes has been investigated and shown to be dependent upon several factors. An incubation medium composed of 10⁻²m K⁺, 5 × 10⁻³m Mg²⁺, 1 mg of glucose per ml, and 1 μCi of ³²PO₄³⁻ per ml, buffered at pH 6.55 with 0.05 mN-2-hydroxyethyl-piperazine-N′-2-ethanesulfonic acid (HEPES), was found to stimulate optimum accumulation of ³²P-orthophosphate. The temperature of incubation, incubation time, the concentration of unlabeled orthophosphate, as well as arsenate, and several metabolic inhibitors were found to affect the accumulation. The labeled cells were collected on a membrane filter, which had been previously boiled in glass-distilled water, for measurement of the radioactivity accumulated. Under optimum conditions, as few as 20,000 cells were capable of accumulating detectable amounts of ³²P-orthophosphate in 1 hr of incubation.     

Inhibition of development of Meloidogyne incognita by root and foliar applications of oxamyl

Oxamyl (2.5 μg cm^-3sand) applied to the roots of cucumber seedlings significantly reduced the number of vermiform second stage juveniles of Meloidogyne incognita which developed into swollen forms for at least 30 days. However, when cucumber seedlings containing nematodes were removed from oxamyl-treated sand 10 days after the pesticide was applied and placed in clean sand a large proportion of the juveniles had become swollen after a further 18 days. This suggested the effect of oxamyl on nematode development was reversible. A single foliar application of oxamyl (25–100 μg) in distilled water was also found to significantly reduce development of second stage juveniles to saccate forms However, the use of various adjuvants with a threshold foliar treatment (25 μg oxamyl) failed to significantly improve its activity.     

The cytology of cotyledon cells and the induction of giant polytene chromosomes inPisum sativum

Summary The cotyledon cells ofPisum sativum have high DNA contents. By appropriate culture techniques, some of these cells can be triggered into division. Two types of dividing nuclei were seen. Firstly those that were polyploid with metaphases containing chromosome numbers ranging in value from 4 x to 32 x. Included among these were unexpected numbers equivalent to 12 x and 14 x. Secondly there were cells containing giant polytene chromosomes and these progressed from prophase to a metaphase where the polytene chromosomes separated into constituent single chromosomes.     

Effects of root and foliar applications of exogenous NO on alleviating cadmium toxicity in lettuce seedlings

The effects of sodium nitroprusside (SNP, a donor of NO) on cadmium (Cd) toxicity in lettuce seedlings were studied. SNP was added into hydroponic systems or sprayed directly on the leaves of plants grown with and without Cd. Excess supply of Cd (100 μM) caused growth inhibition, dramatically increased Cd accumulation in both leaves and roots, and inhibited the absorption of Ca, Mg, Fe and Cu. Excess Cd also decreased activities of superoxide dismutase peroxidase and catalase in leaves and roots, and increased the accumulation of superoxide anion (O ₂ ^·? ), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Root or foliar applications of exogenous NO alleviated Cd-induced growth suppression, especially root application of 250 μM SNP and foliar addition of 500 μM SNP. Addition of SNP promoted the chlorophyll synthesis suggesting that the photosynthesis was up-regulated. Exogenous NO increased Cd-decreased activities of antioxidant enzymes and markedly diminished Cd-induced reactive oxygen species (ROS) and MDA accumulation. Moreover, the absorption of Ca, Mg, Fe and Cu was increased, indicating that exogenous NO stimulated H⁺-ATPase activity to promote sequestration or uptake of ions. In addition, exogenous NO also inhibited Cd transfer from roots to shoots, which may indicate that Cd retention in roots induced by NO plays a significant role in Cd tolerance in lettuce seedlings. These data suggest that under Cd stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, protects lettuce seedlings against oxidative damage by scavenging ROS, helps to maintain the uptake of nutrient elements, and inhibits Cd transferred to shoots effectively.     

Uptake of 3HHO and 32P by roots of wheat and rape

Summary Direct measurements were made of ³HHO and ³²P taken up from labelled soil by roots of wheat (Triticum aestivum L.) and rape (Brassica campestris L.). Single roots were encased in labelled soil for 3 days, and the amount of ³HHO and ³²P retained in the shoots was determined. Plants were grown to five stages of maturity in growth boxes under controlled conditions. Roots were labelled at up to four depths (to 90 cm) depending on the rooting depth at each stage of maturity. Uptake of ³HHO per unit length of root increased as the plant age increased, while uptake of ³²P decreased to below detection levels by 45 days after germination. Larger amounts of both nutrients were translocated to and retained in the shoots from surface roots than from roots located deeper in the soil although the soil was uniform in temperature, bulk density, and composition throughout the growth boxes. Wheat roots were more efficient than rape roots in absorbing ³HHO; however, rape roots took up larger amounts of ³²P per unit length of root. Neither native nor added P located more than 30 cm deep is of much importance to these annual crops, since uptake is minimal and the main demand for this nutrient occurs at early growth stages when the root system is restricted to the surface layers. re]19750812     

Uptake of phosphorus and potassium in relation to root growth and root density

Summary This paper provides some quantitative data on the relationship between the rate of uptake of phosphorus and potassium from soil and the amount of root, root density and rate of root growth. Three experiments were conducted with winter wheat, all grown in the same soil. Root growth and density were manipulated in three ways: (1) by root pruning; (2) by a split-root technique; (3) by growing plants in different soil volumes. Root lengths as well as weights were determined.Potassium uptake per unit amount of root was generally lower the higher the root density, suggesting that roots were competing with each other for potassium even at the lowest density. In contrast, phosphorus uptake showed a good correlation with root growth irrespective of root density or plant age. Phosphorus uptake during a period was more closely and consistently correlated with root growth during that period than with the total amount of root on the plant. The results can be explained in terms of ion supply to the root surface, taking into account the diffusion coefficients of the ions and the approximate distances between neighbouring roots.Now Mrs. Watkins; address 39 Leach Heath Lane, Rubery, Birmingham.Now Mrs. Watkins; address 39 Leach Heath Lane, Rubery, Birmingham.     

Uptake and translocation of calcium in cucumber

Uptake and translocation of Ca²⁺(⁴⁵Ca) were compared with water translocation in 12-day old intact plants and excised roots of cucumber ( Cucumis sativus L. var. Cilla), which had been cultivated in nutrient solution. No immediate reduction of Ca²⁺ uptake was found when water translocation was reduced by excision of the shoot. In the presence of 2,4-dinitrophenol Ca²⁺ translocation was reduced in the intact plants while water translocation was unchanged. It is suggested that regulation of Ca²⁺ uptake is primarily achieved in the root. The DNP-sensitive mechanism of Ca²⁺ uptake was associated with the root and probably represented transport through the endodermis into the stele.     

The Effect of Bicarbonate on P32 Uptake by Tomato and Runner Bean

The effect of bicarbonate on the absorption and translocationof P³² by tomato and runner bean has been investigated. Whilebicarbonate stimulated phosphorus uptake from potassium phosphatesolutions it inhibited it from Hoagland solution. Translocationof absorbed phosphorus was inhibited in the single salt solutionbut stimulated in Hoagland solution. Bicarbonate caused morephosphorus to be concentrated in the stems and less in the leavesin Hoagland solution and the reverse was true in the single-saltsolution. It is concluded that the effect of bicarbonate onphosphorus in causing iron chlorosis in some plants is indirect.     

Influence of brassinosteroids on initiation of the root gravitropic response in Pisum sativum seedlings

In roots of Pisum sativum seedlings, the average lag-time required for initiation of the gravitropic response was reduced proportionally to the concentration of 24-epibrassinolide (EBL) added to the root solution (range of 10⁻¹³ to 10⁻⁸ M concentrations). A treatment with clotrimazole, a compound inhibiting steroid synthesis, prevents initiation of the gravitropic response. This effect was partly reverted by addition of EBL. From analysis of variability in the populations, it is suggested that BR conditions the root curvature through a gravitropic-induced change in sensitivity to the PGRs regulating cell elongation.     

Correlation of spermine levels with ovary senescence and with fruit set and development inPisum sativum L.

Separation and quantitation of polyamines from unpollinated pea (Pisum sativum L.) ovaries and young fruits induced by application of gibberellic acid to unpollinated ovaries showed, in both cases, a decrease in putrescine and spermidine levels between anthesis and 4 d later. By contrast, spermine levels increased prior to the onset of senescence of the unpollinated ovaries (3 d post anthesis) and decreased during fruit development. Low levels of putrescine, spermidine and spermine were also observed in young fruits obtained by self-pollination and by treatment of unpollinated ovaries with 2,4-dichlorophenoxyacetic acid. In-vitro culture of ovary explants in a medium containing spermine showed that a reduction of the growth of gibberellic acid-treated unpollinated ovaries was associated with a rise in the level of spermine in the fruits. The results obtained indicate that changes in spermine levels are involved in the control of ovary senescence and of fruit set and development.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophen-oxyacetic acid - GA₃ gibberellic acid - HPLC high-performance liquid chromatography