摘要:

Seedlings ofPinus sylvestriswere grown for 6 weeks under natural light conditions in a temperature controlled environment room. Cuttings from these plants were rooted in tap water or in indolebutyric acid (IBA) solutions for 60 days at an irradiance of 16 W m‐2. Experiments were performed at 3‐week intervals during two growth seasons. — Seasonal changes in root formation were found in control cuttings as well as in IBA treated cuttings. The number of roots and the percentage of cuttings that rooted were high during early spring and autumn. During the summer period hardly any roots were formed. Stimulation of root formation by IBA occurred manily during spring and autumn when cuttings already possessed the ability to form roots. — The influence of photoperiod during stock plant growth was also investigated. Shorter photoperiod resulted in an increase in the number of roots and rooting percentage. The period during summer where rooting was inhibited under natural light conditions was considerably shortened when stock plants were grown at a photoperiod of only 4 h. The results demonstrate the importance of the growing conditions for stock plants for subsequent root formation. The results are discussed with special reference to the role of irr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06310.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Uptake and translocation of Ca2+(45Ca) were compared with water translocation in 12‐day old intact plants and excised roots of cucumber (Cucumis sativusL. 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

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06311.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The inhibitory action of divalent cations on the Ca2+‐ATPase activity of a plasma membrane‐rich microsome fraction isolated from the roots of barley (Hordeum vulgareL. cv. Conquest) was investigated. Using electron paramagnetic resonance spectroscopy to measure cation‐induced changes in membrane lipid properties, it was demonstrated that certain divalent cations (Ca2+, Cd2+, UO2+2) inhibit the Ca2+ATP‐ase by restriction of lipid polar head group mobility and not by alteration of membrane surface potential. Monovalent cations which stimulate the Ca2+‐ATPase of barley roots (Na+, K+, ethanolamine HCl) can also reverse the Ca2+‐ATPase inhibition by Cd2+. The degree of Na+reversal of Cd2+‐induced Ca2+‐ATPase inhibition was influenced by the natu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06312.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The role of ethylene in the formation of lysigenous cortical cavities (aerenchyma) in seedling roots ofZea maysL. cv. Capella, has been studied under aerated and non‐aerated conditions. Passing roots from air to aerated water or from an aerated nutrient solution to a non‐aerated solution, promoted cavity formation and was accompanied by an increase of the endogenous ethylene concentration. When the endogenous ethylene concentration of roots in aerated nutrient solutions, which otherwise would not produce much cavities, was enhanced by applying ethylene gas (0.1 and 1.0 μl 1‐1in air) or the ethylene precursor 1‐aminocyclopropane‐1‐car‐boxylic acid, cavity formation was promoted. When, on the contrary, the endogenous ethylene concentration of the roots was reduced by adding the inhibitors of ethylene biosynthesis, cobalt ions and aminooxyacetic acid, or when the ethylene action was prevented by silver ions, cavity formation was prevented. It is concluded that endogenous ethylene controls the induction of cavity formatio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06313.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Mitochondria isolated from tobacco (Nicotiana tabacumL. cv. Wisconsin 38) callus growing on either shoot‐forming or non‐shoot forming medium show an increase in state 3 and state 4 respiration and a drop in respiratory control and ADP/O ratios after subculture. the protein content of the mitochondria fraction and the activity of succinate dehydrogenase, malate dehydrogenase, cytochromecoxidase and catalase also increase after subculture but there is no apparent difference between shoot‐forming and non‐shoot‐forming tissue. For mitochondria assayed at their native osmolarities, a trend of higher respiration rates and respiratory control as well as lower levels of cyanide‐resistant respiration was observed for shoot‐forming tissue. Generally, differences were greatest after day 9 in culture, the time during which primordia formation occurred in the shoot‐forming callus. These patterns are in concert with the view that the shoot‐forming process has a high energy requirement which must be realized during the time of pr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06314.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Unrolling of sections from dark grown barley leaves (Hordeum vulgareL. cv. Klages) was stimulated by red irradiation. The unrolling started after a lag phase of 6‐8 h and was completed after 24 h. The effect of several keto and amino acids on leaf unrolling was compared with their effect on coleoptile segment expansion growth. Of the substances tested δ‐aminolevulinic acid had the most inhibitive effect on leaf unrolling and the least inhibitive effect on coleoptile segment expansion growth. Prolonged treatment caused a strong inhibition of the unrolling but with a short tretment, a stimulation of the unrolling occurred. The inhibitive effect of δ‐aminolevulinic acid was only found if the treatment started within 6‐8 h after the red irradiation. Kinetin and gibberellic acid could decrease the inhibitory effect of δ‐aminolevulinic acid. A possible role for δ‐aminolevulinic acid working as a triggering substance for leaf unrolli

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06315.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Mitotic activity was investigated in the primary meristem of horizontally oriented excised root tips ofZea maysduring the first six hours of their georeaction. The only statistically significant change that could be detected in the meristem was a decrease of the length of its upper half. No significant difference in mitotic activity was found between the upper and lower halves of roots kept continuously horizontal for 6 h. Cell proliferation thus seems relatively insensitive to changes in the redistribution of endogenous growth regulators that are believed to occur within the meristem during the onset of geotropism. In the zone of bending proximal to the meristem cell length was significantly greater in the upper half than in either the lower half or in the equivalent position in vertical control roots. Thus, cell elongation seems to be promoted in the upper half of the horizontal root. Thus, The differences in cell length were not accompanied by any change in the proportion of nuclei synthesising DNA in these elongating, non‐meristematic cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06316.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Application of different concentrations of ethephon (2‐chloroethylphosphonic acid) toPapaver somniferumL. at the times of stem elongation, bud, and capsule formation produced different effects. Ethephon (10‐2M) retarded growth of the plant and inhibited capsule formation during stem elongation, significantly reduced capsule size during the flowering period, but did not alter capsule development during capsule formation. When applied during the period of stem elongation, ethephon (10‐3Mand 10‐4M) reduced capsule size; alkaloid accumulation was reduced by ethephon at a concentration of 10‐3M, but slightly increased by 10‐4M. Ethephon (10‐3Mand 10‐4M) did not alter capsule development or alkaloid content significantly when applied during bud formation, but stimulated capsule size and alkaloid content when applied during capsule formation. Pretreating the plants with Ag+(silver nitrate) did not reverse the ethephon effect. The results suggest that capsule maturation and alkaloid accumulation inP. somniferumare modified by ethylene, which is produced as a result of exogenous eth

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06317.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

In the cotyuledonary tissue of cocklebur (Xanthium pennsylvanicumWallr.) seeds, AIB (α‐ aminoisobutyric acid) inhibited not only the endogenous ethylene production but also the ACC (1‐aminocyclopropane‐1‐carboxylic acid)‐dependent and IAA‐induced ones. The inhibition of the endogenous ethylene production by AIB was accompanied by the accumulation of ACC in the tissue. Thus AIB may act as a competitive inhibitor of the conversion of ACC to ethylene and thereby inhibit ethylene production. The promotion of ethylene production by D‐isomers of some amino acids, such as phenylalanine, valine, threonine and methionine was accompained by and increse in the ACC content, the degree of which was similar to that of the stimulation of ethylene production. Moreover, these D‐amino acids stimulated the conversion of exogenously applied ACC to ethylene. The corresponding L‐isomers failed to produce these effects. It seems likely that D‐amino‐acid‐stimulated ethylene production results from the increases of both the biosynthesis and degradation of ACC. Only for tryptophan did both D‐ and L‐isomers cause an increase in ethylene production and in ACC content in the segments. The mechanism of stimulation of ethylene production by the tryptophen isomers is possibly due to their conversion to IA

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06318.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Fumigations of 4–7 week old seelings ofPinus silvestris, with ca 400 μg SO2m‐3for 4–5 days resulted in a decrease both in net photosynthetic rate and in the levels of ribulose bisphosphate carboxylase activity of the primary needles. The effect on net photosynthesis was reversible. No visible damages were observed on the needles. Lower concentrations, ca 200 μg SO2m‐3, for ca 6 days inhibited net photosynthesis reversibly. The effect on net photosynthesis was not the result of stomata closure or of increased respiration. A dose‐response relation for the inhibition of net photosynthesis and ribulose bisphosphate carboxylase is suggested. A similar relation was observed for the chlorophyll content of the needles. The reversible inhibition of photosynthesis was evident only at high quantum flux density, and the quantum yield of photosynthesis at rate limiting quantum flux was not affected. This was also suggested from an experiment with Scots pine i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb06319.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY