Variations in kinetin-like activity in buds of Betula and Populus during release from dormancy

1968 ◽  
Vol 46 (4) ◽  
pp. 397-403 ◽  
Author(s):  
Romuald Domanski ◽  
Theodore T. Kozlowski

Levels of kinetin-like activity in dormant buds and buds at various stages of release from dormancy were determined by an assay involving retardation by kinetin-like substances of chlorophyll degradation in tissue of senescing leaves of Raphanus test plants. Dormancy of buds of Betula papyrifera and Populus balsamifera cuttings was broken by exposure to 2-chloroethanol vapor or immersion in warm water. Water extracts of buds at various stages of dormancy were separated by ascending chromatography and active Rf values identified. The amount of kinetin-like activity at various stages of bud dormancy was then determined by observing effects of active Rf values of bud extracts on senescence (chlorophyll retention) of Raphanus plants. Kinetin-like activity was absent in dormant buds of both species and was present in various amounts after dormancy was broken. In Betula, such activity was found primarily at Rf values of 0.3 to 0.5, and secondarily at 1.0. In Populus, kinetin-like activity was found at Rf values 0.5 to 0.6 and 0.9 to 1.0. Kinetin-like activity was greater in non-dormant buds of Populus than in those of Betula. However, the trend of variation in activity with time after breaking of dormancy was similar in both species. After bud dormancy was broken, kinetin-like activity in both species increased progressively until shortly before buds opened, and it decreased thereafter. Evidence is cited that release of buds from dormancy involves a change in the balance of growth regulators, with various growth promoters increasing to overcome the effects of inhibitors. Endogenous cytokinins appear to be involved, together with other growth promoters, in regulating release of buds from dormancy.

2019 ◽  
Vol 35 (6) ◽  
Author(s):  
Safdar Hussain ◽  
Abdul Rehman ◽  
Muhammad Akram ◽  
Javaid Iqbal ◽  
Tahira Batool Qaisrani ◽  
...  

Empowerment of wheat genotypes by application of growth regulators, compatible solutes and plant extracts under water restriction is an important strategy for getting sustainable yield. Field trail was performed at the research area of the Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Pakistan. Three wheat cultivars Aas-2011, Faisalabad- 2008 and Triple dwarf-1 were subjected to drought stress (skipping the irrigation at grain filling stage). The wheat genotypes were subjected to treatments viz., T1 i.e. All normal irrigation without application of abscisic acid (ABA), salicylic acid (SA), moringa (MLE) and mulberry leaf water extract (MBLE), T2­ i.e. skipping the irrigation at grain filling stage and application of 2µM ABA, T3 i.e. skipping the irrigation at grain filling stage and application of 10 m mol SA, T4 i.e. skipping the irrigation at grain filling stage and application of 15% MLE and T5 i.e. skipping the irrigation at grain filling stage and application of 10% MBLE. The experiment was laid out in Randomized Complete Block Design with factorial arrangement and repeated three times. From this study it is concluded that Aas-2011 shown best result under drought condition by applying growth regulators and plant water extracts. rs and plant water extracts.


1996 ◽  
Vol 74 (5) ◽  
pp. 686-693 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Ross W. Wein ◽  
Petra Lange

Low soil temperatures and water availability are thought to be major factors determining the distribution of tree species at the arctic tree line. A comparative study examined the response of Betula papyrifera, Populus balsamifera, and Picea mariana seedlings to different soil temperatures and drought regimes in a growth chamber experiment. Morphological and ecophysiological responses (net assimilation rate, stomatal conductance to water vapour, and residual conductance) of these tree line tree species were measured and compared. Mean biomass accumulation of the deciduous species was greater than that of Picea mariana with increasing soil temperatures. Root biomass showed an increase of 30% in the three species between the soil temperatures of 3 and 15 °C. Response of ecophysiological variables to increased soil temperature was greater in B. papyrifera and Populus balsamifera than in Picea mariana. In a second experiment, drought-preconditioned B. papyrifera and Populus balsamifera seedlings were subjected to a 6-day water-withholding treatment. Drought decreased shoot mass and increased the root to shoot ratio equally in B. papyrifera and Populus balsamifera. Drought-preconditioned B. papyrifera and Populus balsamifera seedlings responded differently to the 6-day water-withholding treatment. Betula papyrifera used a water-conserving strategy and maintained low net assimilation rates and low water use after drought preconditioning, whereas in Populus balsamifera greater net assimilation rates were associated with drought preconditioning. These results are consistent with the distribution of these three tree species at the arctic tree line. Keywords: Picea mariana, Populus balsamifera, Betula papyrifera, drought preconditioning, soil temperature, arctic tree line.


Botany ◽  
2013 ◽  
Vol 91 (6) ◽  
pp. 343-348 ◽  
Author(s):  
Rongzhou Man ◽  
Pengxin Lu ◽  
Steve Colombo ◽  
Junlin Li ◽  
Qing-Lai Dang

Comparative stress resistance of 1-year-old white birch (Betula papyrifera Marsh.), balsam poplar (Populus balsamifera L.), and trembling aspen (Populus tremuloides Michx.) seedlings was evaluated after exposure to freezing or defoliation. Photosynthesis in leaves surviving freezing (−5 °C) declined immediately after treatment, but nearly fully recovered within 3 weeks. Defoliation did not significantly increase photosynthesis in the remaining leaves. Refoliation occurred after freezing that killed terminal shoots and released current buds from apical dominance, while new leaves of larger size were produced through continuous growth of terminal shoots in 50% or 100% defoliation. Freezing and complete defoliation significantly reduced diameter and height growth in all species, whereas 50% defoliation did not affect growth. These results indicate some of the physiological and morphological responses to foliage loss in broadleaved boreal species that can help to maintain growth and productivity under a warming climate, which may result in more frequent damaging spring frosts and insect defoliation.


HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 760B-760
Author(s):  
William M. Womack ◽  
James E. Barrett ◽  
Terril A. Nell

`Prize' and `Gloria' azaleas were budded at 29C day/24C night without growth regulators. Dormant-budded plants were held at 2, 7, 13, or 18C for 0, 0.5, 1, 2, 4, 6, 8, or 10 weeks and then forced in walk-in growth chambers (29C day/24C night). A model was developed to describe the effect of cooling temperature and duration on days to marketability (eight open flowers) and percent of buds showing color. Holding at temperatures below 7C, increases days to marketability up to 7 days. Extended cooling (beyond 6 weeks) at temperatures <7C increases percent of buds showing color. Extended holding at temperatures >7C decreases buds in color due to development of bypass shoots during cooling and increased bud abortion. Plants not receiving a cool-treatment or cooled for <2 weeks do not flower uniformly. Furthermore, the percentage of plants reaching marketability dramatically decreases for plants held longer than 6 weeks at temperatures >7C. Both cultivars show similar trends, but `Gloria' has greater variability.


2015 ◽  
Vol 43 (3) ◽  
pp. 421-426 ◽  
Author(s):  
L. Witkowska-Żuk ◽  
W. Kozłowska

The course of the particular phases of dormancy of terminal buds from various parts of the tree crown of 12-year-old <i>Fraxinus excelsior</i> trees was investigated. The following treatments breaking dormancy were applied: defoliation, a warm water bath and chilling. Significant differences in the depth of bud dormancy between the main and lateral shoots were noted only in the period of correlated inhibition. No differences could be found either in the course of rest and imposed dormancy or in the process of their receding.


2020 ◽  
Vol 5 (3) ◽  
pp. 268-274
Author(s):  
Sanjeevan Gosai ◽  
Subash Adhikari ◽  
Saugat Khanal ◽  
Padam Bahadur Poudel

This review provides a comprehensive overview of the basic and applied aspects of different plant growth regulators in the regulation of growth and development of cucumber plants. The study is completely based on the use of secondary sources of data; related journals, government institutes, and relevant reports. Foliar application of PGRs has been shown to change the physiological and developmental processes, including plant vegetative growth, sex expression, yield, and yield components in cucumber. There are basically two types of growth regulators; plant growth promoters such as auxin, gibberellins, cytokinins, maleic hydrazide, ethephon, etc. and plant growth inhibitors such as ethylene, abscisic acids, dormins, etc. The combined use of auxins and gibberellins result in increased secondary growth. Maleic hydrazide (MH) along with Ethephon at 100 ppm each increases the number of nodes and primary branches.  Ethrel at 300-400 ppm retards the secondary development and increase femaleness, and at 200-300 ppm make fruit surface smooth. Silver nitrate (AgNO3) at 400 ppm enhances the maleness in cucumber. Application of Ethephon at 300 ppm reduces the harvesting time of the fruit. Salicylic acid (at 2 doses of 0.07 mm/l + 0.18 mm/l) increases chlorophyll content and its exogenous application increases the fruit yield. Maleic Hydrazide (MH) alone at 100 ppm increases the femaleness, inhibits apical growth at 50-100 ppm, and increases fruit size at 200 ppm. Therefore, various auxin [indole-3-acetic acid (IAA), NAA], auxin transport inhibitor (TIBA), cytokinins (KIN), gibberellin [gibberellic acid (GA3)], ABA, ethylene [(2-chloroethylphosphonic acid (ethrel; ethephon; CEPA)] and growth retardant (MH) have been applied to control the vegetative growth and to maximize yield of cucumber. Numerous obstacles have hindered the quality cucumber production in Nepal; like environmental stresses, biotic and abiotic constraints, pest and disease outbreaks, and many others. The use of exogenous plant growth regulators has been crucial to Nepali cucumber producers as plant growth regulators has hasty effect on vegetative as well as the quality yield of plants. This study aims to reveal the suitable concentrations for the applications of growth regulators so that the use of such regulators is environmentally and toxicologically safe for both plants and the consumers.


Investigation of the influence of elements of cultivation technology, such as: sowing time, seeding rates, mineral nutrition, the use of growth regulators and varietal features on productivity of crops and quality of safflower seeds, in specific soil and climatic conditions are relevant. The purpose of the research was to determine the dependence of performance elements and the yield level of safflower varieties on additional mineral nutrition and the use of microbiological preparations. The research was conducted in 2017-2019 at the fields of the Institute of Oil Crops of the NAAS. Soil of the test site – ordinary black soil, medium-sized low humus, with humus content in the arable layer 0-30 cm – 3,5 %, available nitrogen – 7,2-8,5, mobile phosphorus – 9,6-10,3, exchangeable potassium – 15,2-16,9 mg/100 g of soil, pH of soil solution 6,5-7,0. The sowing of the varieties of safflower Zhivchyk and Dobrynya was carried out in the first decade of April with a seeding rate of 240 thousand similar seeds per hectare. Basic tillage system: classic. Options for application of mineral fertilizers: 1. Control – without fertilizers; 2. N60P50 for basic tillage; 3. P50 under basic tillage + N60 under pre-sowing cultivation. Options for the use of growth stimulants: 1. Control – without treatment; 2. Growth concentrate (1.0 l/ha) + Chelatin oil (1.5 l/ha); 3. Chelatin Forte (1.0 l/ha) + Helatin mono boron (1.0 l/ha); 4. Chelatin mono boron (1.0 l/ha) + Phosphate-potassium chelate (1.0 l/ha); 5. Chelatin phosphorus-potassium (0.5 l/ha) + Chelatin multimix (0.5 l/ha) + Chelatin mono boron (0.5 l/ha). The treatment of plants was carried out in phase 6-10 safflower leaves. As a result of the conducted researches the influence of additional mineral nutrition and application of microbiological preparations on the height of plants, indicators of productivity elements and yield of safflower varieties Zhivchyk and Dobrynya were established. Under the influence of fertilizers and growth regulators, the plant height indexes of Zhivchyk varieties increased from 83.0 to 88.5 cm and the Dobrynya varieties from 72.9 to 78.2 cm. N60P50 under basic tillage with the use of Growth Concentrate + Chelatin Oil preparations. The highest values of plant height of safflower of the variety Dobrynya – 78.1 and 78.2 cm are indicated in the variants with the introduction of mineral fertilizers P50 under basic tillage + N60 under pre-sowing cultivation and the use of growth stimulants . Performance indicators of safflower varied under the influence of all the agricultural practices studied. The number of baskets on one plant was in the range: for the variety Zhivchyk 10.3-10.9 pcs, for the variety Dobrynya 9.5-9.9 pcs. Under the influence of mineral fertilizers and growth promoters, their number increased, respectively, for: Zhivchyk 0.1-0.4 and 0.1-0.4, for Dobrynia 0.1-0.3 and 0.1-0.3 piece Indicators of the number of baskets and seeds per plant for both Zhivchyk and Dobrynya varieties were higher against the background of additional nutrition. In the variants with application of mineral fertilizers in relation to the control the number of baskets and seeds per plant increased by 0.1-0.3 and 4.1-12.9 pcs. in the variety Zhivchyk and 0.1-0.3 and 7.9-12.6 pcs. in the variety Dobrynya. Under the influence of growth stimulants, the number of baskets and seeds per plant increased by 0.1-0.4 and 1.9-10.5 pcs. in the variety Zhivchyk and by 0.1-0.3 and 0.2-4.7 pcs. in the variety Dobrynya. Indicators of seed weight per plant and weight of 1000 seeds increased depending on the use of mineral fertilizers and growth promoters. Under the influence of mineral fertilizers, they increased by: 0.47-0.82 and 1.4-1.9 g in the Zhivchyk variety; 0.73-0.95 and 2.0-2.4 g in the Dobrynia variety. Under the influence of growth promoters, these indicators increased by 0.12-0.61 and 0.8-1.3 g in the Zhivchyk variety, 0.13-0.46 and 1.2-1.8 g in the Dobrynya variety. The highest weight of 1000 seeds is 39.8 g in the Zhivchyk variety and 49.5 g in the Dobrynya variety obtained on the background of fertilizer application N60P50 under the main cultivation of the soil with the use of Growth Concentrate + Chelatin oil. Depending on the mineral nutrition background and the use of growth stimulants, the level of yield of safflower of the Zhivchyk variety was in the range of 1.46-1.71 t/ha, of the Dobrynya variety 1.55-1.85 t/ha. The increase from the application of mineral fertilizers was equal to: for the Zhivchyk variety 0.11-0.17 t/ha, for the Dobrynia variety 0.17-0.22 t/ha. Depending on the variant of application of the preparations, the yield of safflower increased by: 0.05-0.12 t/ha in the Zhivchyk variety and 0.03-0.11 t/ha in the Dobrynya variety. The highest yield of safflower of the Zhivchyk variety – 1.71 and 1.70 t/ha and the variety Dobrynya – 1.84 and 1.85 t/ha were obtained on the background of application of mineral fertilizers at a dose of N60P50 for the main cultivation of soil with the use of Growth Concentrate + Oil chelate and Mono boron chelate + Phosphorus-potassium chelate.


1982 ◽  
Vol 12 (4) ◽  
pp. 931-935 ◽  
Author(s):  
Richard W. Tinus

Dewinging stored seed of green ash (Fraxinuspennsylvanica Marsh.) increased speed of and total germination. Fresh seed germinated best with a 4-day warm-water soak followed by 30-day stratification at 3 °C. Best procedures for stored seed were a 4-day soak in 100 ppm giberellic acid or a 2-day soak in 1 – 10 ppm 6-benzyladenine, followed by 30-day stratification at 3 °C.


1976 ◽  
Vol 6 (1) ◽  
pp. 1-5
Author(s):  
R. L. Edmonds

Western hemlock (Tsugaheterophylla (Raf.) Sarg.) heartwood is extremely susceptible to decay by Fomesannosus (Fr.) Karst. Cold-water extracts from nondecayed heartwood mildly inhibited growth of F. annosus in culture, but cold-water extracts from incipient and advanced decayed heartwood stimulated growth slightly. Compounds in cold-water extracts were not identified. Warm-water extracts generally stimulated growth of F. annosus. Phenolic compounds that were extracted by warm-water treatments from nondecayed heartwood were catechin, leucocyanidin, hydroxymatairesinol, and matairesinol. Ultraviolet spectrophotometry and paper chromatography revealed that F. annosus was capable of modifying and (or) utilizing these phenolic compounds. However, concentrated leucocyanidin in culture slightly inhibited growth of F. annosus. The high susceptibility of western hemlock heartwood to decay by F. annosus is apparently related to the absence of strongly fungitoxic heartwood extractives.


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