摘要:

Growth and uptake of N, P, S, K, Ca and Mg in barley (Hordeum vulgareL.) were studied in water culture using young plants of 17 cultivars. Large varietal differences were obtained in dry weight production and mineral accumulation. The differences were not the same for plants grown in high‐ and low‐salt media. For plants grown under both conditions there was a good correlation between dry weight production and total N content. Total shoot contents of K and Ca were closely correlated with shoot dry weight. Utilization of P and S in high‐ and low‐salt plants and Mg in low‐salt plants was variable in relation to dry weight production in both types of nutrient conditions. The correlation between dry weight and total content of Mg in high‐salt plants was good. These differences in mineral economy between young barley plants were partly caused by varietal differences in relative growth rate, and in high‐salt seedlings also by differences in seed content of N. The significance of root size, and of uptake, root‐shoot partitioning and use‐efficiency of specific elements differed; all four factors were important for P and S, but had varying impact on K, Mg and Ca. For N, differences in root size and ion accumulation were the most important factors causing varietal variation in mineral nutrition. – In a special experiment seedlings of barley were transferred to N‐free nutrient solution after six days of adequate N supply. There was no significant varietal differences in use‐efficiency ratio of N. Root/shoot partition

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04173.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In order to obtain optimum conditions for in vitro propagation of the apple rootstock M 26 (Malus pumilaMill.) in adult and juvenile growth phases, several rooting experiments were performed. Supraoptimal concentrations of indole‐3‐butyric acid (IBA) added to the rooting media resulted in profuse callus formation. Since extensive callus production is detrimental to the survival of the plantlets, modified culture conditions were established to reduce callus formation. A reduction of the time of exposure to IBA to 5 days and, thereafter, transfer to a hormone‐free medium did not eliminate callus production. Exposure to darkness during the root initiation phase increased rooting. When the rooting medium was based on the Lepoivre formula instead of the Murashige and Skoog formula, callus formation was reduced. Optimum conditions for rooting were obtained at much lower concentration than earlier reported, being 1.25 μM for the juvenile and 0.5 μM for the adult growth phase in the range of IBA concentrations tested. Anatomical studies revealed that root initials are formed after 5 days of IBA‐treatment. Therefore, we transferred shoots directly to non‐sterile conditions after the root‐inducing phase. This resulted in a 90% survival of the plantlets. Subculture on hormone‐free medium can thus be eliminated when the optimum auxin concent

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04174.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The growth‐promoting (benzyladenine) and growth‐inhibiting (abscisic acid) plant hormones, when used at concentrations of 0.4 and 4.0 μM, affect the development of superoxide dismutase (SOD) activity ofLemnafronds in opposite ways, the former hormone decreasing the activity and the latter increasing it. The effect of both growth substances is on de novo synthesis of the enzyme. In addition abscisic acid also causes the Zn, Cu and protein contents of the fronds to increase, while benzyladenine has the opposite af

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04175.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Germination experiments on isolated embryos and intact achenes fromRosa rugosaL. var.rubrarevealed the existence of both coat‐induced and embryo dormancy. Studies were made on the quantitative changes in abscisic acid (ABA) of achenes during both a stratification period at 4°C and a subsequent germination period at 20°C. Controls were run in parallel at 17°C. Dormant, unimbibed achenes contained large amounts of ABA. The level fell rapidly during the early stages of stratification at 4°C, mainly due to leakage, and then the decline levelled off. The reduction of ABA content during germination was less and followed a tri‐phasic pattern. Under the control conditions, the ABA level also fell although still faster, the amounts present being consistently below those detected in the corresponding cold‐stratified samples. The content of alkali‐hydrolysable ABA was low and not affected either by the duration or by the temperature of stratification. The investigation shows that termination of dormancy is not simply a consequence of a fall in the content of endogenous ABA and supports the current debate questioning the central role of ABA in regulation of dormancy breakage and of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04176.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

δ‐Aminolevulinate dehydratase (ALAD) is synthesized in the cytoplasm and subsequently transported into the plastids in cotyledons of tar‐red irradiated radish (Raphanus sativusL. ev. Longue Rave Saumonée). The intra‐cellular localization of ALAD activity was determined under far‐red irradiation and darkness. After 60 h far‐red, ALAD was essentially eytoplasmic; 96 h far‐red corresponded to a peak in total ALAD activity, as well as the onset of massive ALAD transfer into the plastids, and after 120 h a maximum enzyme activity was located in the plastids. Under dark conditions, essentially no transport of ALAD was noted.Structural modifications of plastid‐eytoplasmic relationships were analysed at the three developmental periods under dark and far‐red conditions. 60 h far‐red induced a change in the “elasticity” of plastid envelopes leading to envelope proliferations and amoeboid shaped plastids. After 96 h tar‐red, membrane proliferations formed a highly evaginated plastid periphery. It is suggested that these membranes form a transport network between the two compartments. Also at 96 h, numerous vesicles, which appear to originate from the endoplasmic reticulum (ER), surround the plastid profile. On the basis of the structural observations, it is proposed that ALAD would be synthesized within the ER and transported toward the plastids via ER extensions, which take the form of smooth vesicles. Our hypothesis is that the transition vesicles and proliferations of the outer envelope membrane undergo a fusion process emptying the content of the vesicle into the intermembr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04177.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Apparent sucrose uptake. ATPase activity and membrane fluidity changes were studied during the development and senescence of carnation flowers (Dianthus caryophyllusL., cv. Cerise Royallette). Typical changes associated with senescence of a cut flower, such as respiration, ethylene production and fresh weight, were measured. Concomitant with a rise in respiration and ethylene production and a decline in fresh weight, a sharp decrease in apparent sucrose uptake was observed. Sucrose uptake was pH dependent (pH optimum, 5.5) and influenced by membrane integrity. Apparently, the activity of ATPase is related to sucrose uptake, because similar changes occurred during flower development. In addition, the activity of ATPase was well correlated with membrane fluidity.It is suggested that sucrose uptake is controlled by ATPase activity, which in turn is modulated by membrane lipid fluidity. The decline in membrane fluidity associated with senescence leads to a corresponding reduction in ATPase activity and sucrose uptake. Further evidence supporting this view comes from experiments in which senescence was enhanced by 1‐aminocyclopropane‐l‐carboxylic acid. It shortened the time to decline in fresh weight, rise in respiration and ethylene production. In parallel, reduction in membrane fluidity, ATPase activity and sucrose uptake were obs

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04178.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The apoplastic movement of sucrose through storage parenchyma discs (2.4 mm thick) from roots of sugar beet (Beta vulgaris var. altissima) was investigated in order to evaluate the suitability of the apoplast for transcellular sugar transport. The sucrose permeability of the discs (P = 5.7 × 10−8cm s−1at 25°C) was more than two orders of magnitude lower than that of an equally thick layer of unstirred water. This is due to the small volume fraction of free space (3.1%) and the decreased diffusion coefficient D of sucrose in the cell walls. The effective diffusion coefficient of the apoplast (6 to 9 × 10−7cm2s−1at 25°C) was determined independently of the cross sectional area of free space by treating the time course of fluxes according to Fick's second law. The high diffusion resistance of the apoplast has to be considered in models of native parenchym

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04179.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

IAA‐induced proton excretion in peeled or abraded oat (Avena salivaL. cv. Victory) coleoptiles is closely associated with IAA‐induced growth. It was attempted to separate these two processes by using cycloheximide to inhibit them differentially. Growth of abraded coleoptile segments was measured by a shadow graphic method, and their IAA‐induced acidification of the external solution was monitored with a pH meter. IAA stimulated proton excretion in abradedAvenacoleoptile segments after a 13 min lag. IAA‐induced proton excretion was inhibited within 5 min by cycloheximide at concentrations of 1.8 × 10−6, 3.6 × 10 or 3.6 × 10−5M. Cycloheximide at these concentrations, added within 4 min of IAA, prevented IAA‐induced acidification of the medium for at least 60 min. However, it did not prevent IAA‐induced growth during this time. It is concluded that some of the initial IAA‐induced growth seen inAvenacoleoptiles is independent of detectable IAA‐in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04180.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The incorporation of 1‐[14C]‐palmitate into the lipids of microsomal and mitochondrial membranes from peas (Pisum sativumL., var. Massey Gem) and the relative effects of ATP and coenzyme A(CoA) on the process have been examined. Both mitochondrial and microsomal pellets possessed acyltransferase capacity, which responded similarly to additions of ATP and CoA. Incorporation of 1‐[14C]‐palmitate into phospholipid was promoted by ATP alone, but incorporation into triacylglycerols was not. The addition of CoA alone did not promote incorporation. The addition of CoA and ATP further promoted incorporation into phospholipids and also stimulated incorporation into triacylglycerol. It was concluded that some CoA must be membrane‐bound and available for phospholipid but not for triacylglycerol synthesis. Phospholipase A, treatment of microsomal and mitochondrial phospholipids, previously labelled with 1‐[14C]‐palmitate in the presence of ATP and coenzyme A, showed that incorporation occurred only into the 2‐position of phosphatidyl choline and phosphatidyl ethanolamine.There was enough lyso‐phosphatidyl choline in the phospholipids of microcomal membranes (obtained from a 100 000gpellet) to account for the observed incorporations of palmitate. Using microsomal membranes whose fatty acyl groups were pre‐labelled by incubation of tissue with 1‐[14C]‐acetate, no evidence of acyl exchange was found during subsequent incubations with unlabelled palmitate. Similar observations were made using oleate instead of palmitate. It was concluded that acyl‐CoA: 1‐acylglycerophosphocholine o‐acyltransferase (E.C. 2.3.1.23) was responsible for the observed acyl transfer to phosphatidyl choline.Sucrose gradient analysis of whole homogenates and of the 10 000gpellet showed that both mitochondrial and rough endoplasmic reticulum possessed acyltransferase capacity, with the bulk of this residing in the mitochondria. The possible significance of this widely distributed membrane

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04181.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Callus was initiated form different vegetative parts of 3 to 5‐week‐old seedlings ofPinus roxburghiiSargent. Best results were obtained on Murashige and Skoog's revised medium supplemented with 4 mg1−1NAA or 2,4‐D, 1 mg1−1kinetin and 15% coconut milk. Callus was grown successfully for more than a year without deterioration in its growth. Growth rate studies on the calli form cytoledon explants were undertaken with different concentrations of auxins and cytokinins. Histogenic differentiation of tracheids ocurred in all the calli, with the formation of bordered pits preceding the reticulate thickenings of the tracherary walls. Cells in the 4 to 12‐week‐old calli were predominantly diploid, though a few polyploid and aneuploid cells were also noticed. Chromosome bridges and laggards were observed in a nu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04182.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY