Kinetin Solution Research Articles

Thin layer chromatography of plant phospholipids of Zea mays (L.) un-der the action of the phytohormone kinetin in different aeration condi-tions

Under extreme weather conditions, crops are exposed to excess rainfall, causing the acute oxygen starvation of plants. The treatment of plants with phytohormones started in order to increase plant resistance to stresses. Using thin layer chromatography, the effect of the phytohormone kinetin on the content of plant phospholipids was studied under different aeration conditions. A kinetin solution (10 mg l-1) was injected into the etiolated maize seedlings separated from the roots by the suction method with a transpiration current and seedlings were transferred to aeration conditions, hypoxia or carbon dioxide (9 hours). Control plants were not treated with kinetin. Samples were fixed with boiling isopropanol and extracted with a hexane:isopropanol mixture (3:2). After purification from non-lipid impurities, lipids were evaporated and dissolved in chloroform. Phospholipids were isolated on silica gel W plates and further separated into classes on silica gel 60G plates. (“Merk”, Germany). It was found that the content of total phospholipids in maize seedlings decreased to 84.9% under hypoxic conditions and to 54.5% in CO2. If plants were pre-treated with kinetin, the content of total phospholipids practically did not change (96.2%), and in CO2 it increased to 88.5%. When plants were treated with kinetin under aeration conditions, the content of phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatilylethanolamium (PEA) increased, and phosphatidylglycerol (PG) decreased by almost 40%. Under conditions of oxygen deficiency, changes in the composition of phospholipids were different. The content of PS and PC in seedlings increased by1.5-2.0 times, and the content of PG and PEA decreased to 27.2% and 20.0% of the control. Treatment of maize seedlings with kinetin reduced the effect of gaseous media on the content of all analysed classes of phospholipids in plants, this was especially evident in CO2. Thus, it can be considered proven that the protective effect of kinetin is realized due to the ability of this phytohormone to maintain the optimal content and ratio of phospholipid components characteristic of a given tissue in plants exposed to various unfavourable environmental factors, including oxygen deficiency and high concentrations of carbon dioxide.

Effectiveness of the bacterial biofertilizer (Azotobacter), Gibberellic ac-id and kinetin solution in metabolic some the physiological processes of Psidium guajva L. seedlings

The experiment was carried out in the College of Agriculture - University of Karbala at the beginning of September of the year 2022 according to a randomized complete block design to study the effect of the bacterial biofertilizer Azotobacter and a solution of gibberellic acid (0, 150 and 300 mg. L-1), and kinetin (0, 25 and 50 mg. L-1) in changes of metabolic some physiological processes of Psidium guajava L. seedlings. The results showed that the single effect of the Azotobacter was superior in all studied characteristics, except for the relative moisture content compared to the control treatment, as for the gibberellic acid solution, the concentration (300 mg.L-1) was superior by giving it the highest significant increase in all studied traits except for the relative moisture content compared control treatment, while the treatment of seeds with chitin solution excelled, and the concentration (50 mg.L-1) recorded the highest significant difference in all studied traits except for the characteristic of the degree of stability of cell membranes.

The Effect of the Bacterial Biofertilizer Azotobacter and Gibberellic Acid Solution and Kinetin in Germination of Guava Seeds (Psidium guajava L.)

The study was carried out in the College of Agriculture - University of Kerbala at the beginning of September of the year 2022, according to a factorial experiment with a completely randomized block design, to study the effect of bacterial biofertilizer Azotobacter, and a solution of gibberellic acid in three concentrations (0, 150 and 300 mg. L-1), and a solution of kinetin in three concentrations (0, 25 and 50 mg. L-1) in germination of guava seeds (Psidium guajava L.), the results showed that the single effect of the biological fertilizing agent was superior in the all studied characteristic, except for the characteristic of germination energy after ten days compared to the control treatment. As for gibberellic acid, the concentration (300 mg. L-1) gave it the highest significant increase in all the studied traits compared to the control treatment. Also, the treatment of seeds with kinetin excelled, as the concentration (50 mg. L-1) recorded the highest significant difference in all the studied traits, compared to the control treatment, which recorded the lowest rate.

Diverse Effect of Two Cytokinins, Kinetin and Benzyladenine, on Plant Development, Biotic Stress Tolerance, and Gene Expression.

The plant hormones cytokinins affect a various array of plant growth and development processes as well as responses to biotic and abiotic stresses. In this study, the opposite effect of two different cytokinins kinetin (N6-furfuryladenine) and benzyladenine (BA) on development and on the tolerance of Arabidopsis and tobacco plants to virus, bacteria, and fungi infection was reported. Treatments of Arabidopsis and tobacco seedlings with saturated solutions of BA inhibited plant progress, while treatments with saturated water solution of kinetin promoted plant development. Furthermore, BA pre-treatments strongly reduced the number of TMV (Tobacco mosaic virus) lesions on tobacco and the tissue damage caused by the incompatible Pseudomonas bacteria on Arabidopsis and tobacco leaves. Similarly, BA pre-treatment significantly reduced the necrotic disease symptoms of Botrytis cinerea infection. Kinetin pre-treatments had a much weaker or no protective effect on the damage caused by the above pathogens. Accordingly, Arabidopsis gene expression profiles after treatments also showed that the two cytokinins have different effects on several plant processes. The gene expression results supported the more robust effect of BA, which up and downregulated more than 2000 genes, while only 436 genes were influenced by kinetin treatment. It is noteworthy that BA and kinetin treatment changed gene expressions in the same direction only in a relatively few cases (73 upregulated and 70 downregulated genes), and even 28 genes were regulated into the opposite directions by BA and kinetin. Both treatments had a strong effect on auxin and gibberellin-related genes, but only BA had a significant effect on cytokinin-induced processes. While kinetin exclusively activated the flavonoid synthesis genes, BA affected more significantly protein synthesis, photosynthesis, and plant defence-related genes. In conclusion, BA solution had sometimes the opposite and generally a much stronger effect than kinetin solution not only on the development and on biotic stress tolerance of tobacco and Arabidopsis plants but also on the gene expressions. The stronger protective effect of BA to necrotic stresses is probably due to its stronger senescence inhibitory effect on plant tissues, as supported by the stronger chlorophyll retardation of the BA-treated leaves.

EFFECTS OF HIGH TEMPERATURE AND WATER STRESS ON DORMANCY AND GERMINATION OF SORBUS SIBIRICA SEEDS

A research was carried out into the peculiarities of dormancy and germination of Sorbus sibirica seeds with short-term interruption of cold stratification (1–3oC) by temperature and water stress (rapid drying at 25oC). To induce germination, a laboratory method for stratifying freshly isolated intact (unsaturated) seeds at 1–3oC was used. The homogeneity of the seed sample was monitored by SDS-PAGE and ISSRPCR. The seeds were stratified at 1–3oC for 45, 59, 73 and 87 days, and the stratification was interrupted by rapid drying at 25oC for 1, 3, 7 and 14 days. After drying the experiment was continued in two versions: the seeds were soaked in cold (1–3oC) water or phytohormones (48 hours in gibberellic acid (GK3) solution of 100 mg/l, then 48 hours in kinetin (K) solution of 500 mg/l). Then the seeds in all variants were re-stratified at 1–3oC for 60 days, and germinated at 25oC for 72 hours, the percentage of germination and the lengths of the roots being estimated. It was established that interruption of cold stratification by rapid drying, irrespective of the method of subsequent processing (phytohormones or water), had a strong stimulating effect on germination in Sorbus sibirica seeds. In most variants more than 90% of the seeds germinated. Earlier experiments with continuous cold stratification of intact Sorbus sibirica seeds showed that 17–19% of seeds germinated within 105 days. Changed duration of stratification before drying did not affect the percentage of germination: it remained highest in all variants. The longer stratification lasted, the greater the length of the roots was. Significant deviations in forming seedlings were observed in seeds treated with phytohormones: the roots did not practically develop; their length after 72 hours of germination was 10–20 times lesser than that in seeds treated with water. Cotyledons, on the contrary, increased significantly, and were pale green. Two-stage cold stratification with intermediate temperature and water stress makes it possible to achieve more than 90% germination of seeds without phytohormones.

Effect of ethanol and plant growth regulators on termination of potato microtuber dormancy

Abstract The duration of dormancy varies significantly among cultivars, but even short dormancy can limit usage of potato microtubers for seed production. The aim of the research was to test efficacy of dormancy breaking by treatment with an aqueous solution of ethyl alcohol, saccharose, gibberellic acid and kinetin (ethanol treatment) in comparison to treatment with aqueous solution of thiourea, daminozide and gibberellic acid (standard treatment). Prolonging the period of microtuber production at the in vitro stage significantly favored the short-ening of the dormancy and facilitated its breaking. While the standard treatment had the strongest effect, the ethanol treatment was slightly less efficient. The statistically significant differences were only observed during the first 13 days after the microtuber treatment. After that time, efficacy of ethanol and standard treatments was similar to control treatment with water. The investigated treatments had no effect on the natural decrease of ABA level in microtubers.

Judicious use of kinetin to improve growth and yield of rice in nickel contaminated soil

ABSTRACTThe present study was conducted to evaluate the effect of kinetin on growth and yield of rice in the presence and absence of nickel contamination. Rice seedlings were dipped in kinetin solution (10−3, 10−4 and 10 M−5) for 2 hours and transplanted in pots having soil contaminated with nickel sulfate @ 130 mg kg−1. Experiment was laid out according to completely randomized design with four replications. Results revealed that kinetin significantly improved growth and yield of rice grown in nickel contamination. Kinetin @ 10−4 M showed maximum improvement in plant height, paddy yield, 1000 grain weight, number of tillers and panicles up to 9.76, 15.72, 11.77, 11.87, and 10.90%, respectively, as compared to plants grown in contaminated soil without kinetin. Kinetin also improved the uptake of nutrients (NPK) in straw and grain of plants grown in Ni contaminated soil. Plants treated with kinetin had more concentration of Ni in shoot but less in grain compared to plants grown in Ni contaminated soil without application of kinetin. The application of kinetin can reduce stress effect on plants through improvement in the biomass of plant. This strategy could be used to increase the phytoextraction of Ni from the contaminated soil.

Physiological Strategies to Improve the Performance of Spring Maize (Zea mays L.) Planted under Early and Optimum Sowing Conditions.

Low temperature at stand establishment and high temperature at reproductive stage are involved in reduction of grain yield of spring maize. A field study was therefore conducted to evaluate different physiological strategies for improving performance of spring maize under temperature extremes. Seed priming and foliar spray with 3% moringa leaf extract (MLE) and 100 mg L-1 kinetin solution alone or in all possible combinations with each other at three growth stages (knee height, tasseling and grain filling stage) and hydropriming was compared with control. Seed priming plus foliar spray of MLE and kinetin significantly improved stand establishment especially under early sown crop as indicated by reduced mean emergence time (MET), improved emergence index (EI) and final emergence percentage (FEP). Similarly increased chlorophyll contents, crop growth rate, leaf area index, photosynthetic rate, transpiration rate, relative water content and decreased membrane permeability were recorded in both early and optimum sowing conditions in MLE priming plus foliar spray treatment. All these improvements were harvested in the form of increased yield and harvest index compared with control treatment. Overall crop sown at optimum time performed best but exogenous application of MLE through seed priming and foliar spray maximally improved the performance of early sown maize crop which is attributed more likely due to improved stand establishment, chlorophyll and phenolic contents, increased leaf area duration and grain filling period. It can be concluded that seed priming with MLE along with its foliar spray could increase production of maize under temperature extremes.

Binding of the plant hormone kinetin in the active site of Mistletoe Lectin I from Viscum album

The crystal structure of the ribosome inhibiting protein Mistletoe Lectin I (ML-I) derived from the European mistletoe, Viscum album, in complex with kinetin has been refined at 2.7Å resolution. Suitably large crystals of ML-I were obtained applying the counter diffusion method using the Gel Tube R Crystallization Kit (GT-R) on board the Russian Service Module on the international space station ISS within the GCF mission No. 6, arranged by the Japanese aerospace exploration agency (JAXA). Hexagonal bi-pyramidal crystals were grown during three months under microgravity. Before data collection the crystals were soaked in a saturated solution of kinetin and diffraction data to 2.7Å were collected using synchrotron radiation and cryogenic techniques. The atomic model was refined and revealed a single kinetin molecule in the ribosome inactivation site of ML-I. The complex demonstrates the feasibility of mistletoe to bind plant hormones out of the host regulation system as part of a self protection mechanism.

Improving the Performance of Wheat by Seed Priming Under Saline Conditions

AbstractSalinity is one of a major threat in harvesting good wheat stand on sustained basis. In this study, potential of seed priming techniques to improve the performance of wheat varieties (SARC‐1 and MH‐97) in a saline field was tested. For priming, wheat seeds were soaked in aerated solution of ascorbate (50 mg l−1; ascorbate priming), salicylic acid (50 mg l−1; salicylicate priming), kinetin (50 mg l−1; kinetin priming) and CaCl2 (50 mg l−1; osmopriming) for 12 h. For comparison, seeds were also soaked in simple water (hydropriming); in addition, untreated seeds were also taken as control. Seed priming treatments substantially improved the stand establishment; osmopriming (with CaCl2) was at the top however. Likewise maximum fertile tillers, grains per spike, 1000‐grain weight, grain yield and harvest index were observed in plants raised from seeds osmoprimed (with CaCl2) followed by ascorbate priming in both the varieties tested. As an index of salinity tolerance, seed priming treatments also improved the leaf K+ contents with simultaneous decrease in Na+ concentration, osmopriming being the best treatment. Similarly, maximum total phenolic contents, total soluble proteins (TSP), α‐amylase and protease activities were observed in osmoprimed (with CaCl2) seeds followed by ascorbate priming. Economic analysis also indicated that osmopriming is more viable with maximum net return and benefit‐to‐cost ratio. In conclusion, different seed priming treatments in wheat seeds improved the salinity tolerance nonetheless osmopriming (with CaCl2) was the most effective treatments to get higher grain yield and net return in both wheat varieties whereas kinetin was the least effective.

Enhancement of antioxidant defense system induced by hormonal priming in wheat

Use of plant hormones as seed priming agents is known to improve the field performance especially under stressful conditions like salinity. A pot experiment was conducted to study the effects of seed priming of two wheat (Triticum aestivum L.) cultivars Auqab-2000 (salt tolerant) and MH-97 (salt sensitive) under saline (15 dS m−1) and non-saline (2.75 dS m−1) conditions. For priming seeds were soaked in aerated water (hydropriming), and solutions of kinetin (Kin; 25 mg L−1), or salicylic acid (SA; 50 mg L−1) for 12 h. All the priming treatments significantly reduced the adverse effects of salinity in terms of improving final emergence, growth and grain yield of both cultivars. Seed priming with SA and Kin improved salt tolerance in both wheat cultivars by the activation of antioxidants, i.e. superoxide dismutase (SOD) and catalase (CAT) to counterbalance the oxidative damage. Albeit, Na+ and Cl− contents increased due to salinity, all priming strategies lowered the accumulation of Na+ and enhanced the accumulation of K+ in leaves of both cultivars. The results suggest that priming with SA followed by kinetin successfully improved fitness of wheat plants exposed to salt stress.

Growth and photosynthetic characteristics of Nigella sativa L. as affected by presowing seed treatment with kinetin

Black cumin (Nigella sativa L.) seeds were surface-sterilized and soaked for 5, 10, or 15 h in 1, 10, or 100 μM aqueous solution of kinetin (KIN). The potted plants were then analyzed at 30, 50, and 70 days after emergence (DAE) for dry mass (DM), leaf area (LA), chlorophyll (Chl) content, stomatal conductance (gs), carbonic anhydrase (CA), and nitrate reductase (NR) activity, total protein content, and net photosynthetic rate (PN). Capsule number and seed yield were determined at harvest (90 DAE). Treatment with the growth regulator was found to appreciably enhance all the determinants, with most prominent results being obtained following 10-h soaking with 10 μM KIN, in which case the values for DM, LA, PN, CA and NR activity, and seed yield were elevated by 55, 63, 43, 38, 29, and 23% respectively over the control at the 50-day stage.

Kinetin Increases Chromium Absorption, Modulates Its Distribution, and Changes the Activity of Catalase and Ascorbate Peroxidase in Mexican Palo Verde

This report shows, for the first time, the effectiveness of the phytohormone kinetin (KN) in increasing Cr translocation from roots to stems in Mexican Palo Verde. Fifteen-day-old seedlings, germinated in soil spiked with Cr(III) and (VI) at 60 and 10 mg kg(-1), respectively, were watered every other day for 30 days with a KN solution at 250 μM. Samples were analyzed for catalase (CAT) and ascorbate peroxidase (APOX) activities, Cr concentration, and Cr distribution in tissues. Results showed that KN reduced CAT but increased APOX in the roots of Cr(VI)-treated plants. In the leaves, KN reduced both CAT and APOX in Cr(III) but not in Cr(VI)-treated plants. However, KN increased total Cr concentration in roots, stems, and leaves by 45%, 103%, and 72%, respectively, compared to Cr(III) alone. For Cr(VI), KN increased Cr concentrations in roots, stems, and leaves, respectively, by 53%, 129%, and 168%, compared to Cr(VI) alone. The electron probe microanalyzer results showed that Cr was mainly located at the cortex section in the root, and Cr distribution was essentially homogeneous in stems. However, proven through X-ray images, Cr(VI)-treated roots and stems had more Cr accumulation than Cr(III) counterparts. KN increased the Cr translocation from roots to stems.

Growth Regulators and Chemicals Stimulate Germination of Leafy Spurge (Euphorbia esula) Seeds

Baseline information on inducing germination of dormant leafy spurge seeds with growth regulators and chemicals is lacking. This study was conducted to survey the effect of various substances on germination of leafy spurge seeds. The nontreated control seeds in this population were nearly fully imbibed in 3 h and displayed approximately 35% germination in 21 d under the normal alternating temperature of 20/30 C (16/8 h). Gibberellic acid (GA3, 10 mM) induced 65% germination at constant temperatures of 20 and 30 C. The alternating temperature increased the effectiveness of 10 mM GA3with 94% germination, a twofold increase over the control. Nontreated seeds did not germinate at the constant temperatures, suggesting that alternating temperature acts via a GA-independent pathway. Kinetin at 0.1 to 1 mM was no more effective than the control, but a saturated solution of kinetin induced 73% germination. Ethephon at 0.01 to 1 mM induced 58 to 66% germination, although there was little response to different concentrations. Ethylene gas at 1 ppm stimulated germination to 77%, a 1.8-fold increase over the control. Germination of seeds incubated continuously in 1 and 10 mM nitrate displayed 35 and 40% germination, respectively. Seeds pulsed for 24 h with 100 mM nitrate displayed 58% germination after 21 d. Potassium phosphate–citrate buffer (pH 3.4) and its individual components induced 60 to 70% germination. Fluridone (10 and 100 µM), 1-naphthaleneacetic acid (NAA, 0.1 to 10 mM), and ethanol (0.2 to 15%) had no effect on germination, but subsequent elongation in the presence of NAA was inhibited because of swelling of the radicle. This research reveals that GA3is the most effective growth regulator for germination of dormant leafy spurge seeds, and its effect is independent of temperature.

Responses of Nigella sativa to foliar application of gibberellic acid and kinetin

Foliar sprays of water or 1, 10 and 100 µM aqueous solutions of gibberellic acid (GA3) or kinetin (KIN) were applied to 40-d-old plants of Nigella sativa (L.) to study their effects on net photosynthetic rate, nitrogen metabolism, and the seed yield. 10 µM solutions of both the hormones, especially GA3, appreciably increased the activities of nitrate reductase and carbonic anhydrase, chlorophyll and total protein contents and net photosynthetic rate in the leaves, along with capsule number and seed yield plant−1, at harvest.

Depigmentation and rejuvenation effects of kinetin on the aged skin of hairless descendants of Mexican hairless dogs.

The depigmenting and anti-aging effects of kinetin (KN) solutions on the aged skin of hairless dogs were clinically and histologically investigated. Grossly, all KN-treated sites became mildly depigmented. At 50 days of topical treatment with KN solutions, apparent improvement was observed in the skin texture, wrinkling, and pigmentation. At 100 days of KN treatment, both the skin rejuvenation and depigmentation effects became more prominent. Throughout the experimental period of KN treatment, no adverse effects were found in any sites treated with KN solutions. In the colorimetric system, at 100 days of topical treatment with KN solutions, the L* and b* values in the sites treated with KN solutions significantly increased. Histologically, at 50 days of topical treatment with KN solutions, the KN-treated sites showed a decrease in the thickness of the corneal layers. Melanin granules decreased throughout all epidermal layers. In the dermis, the large number of fine collagen and elastic fibers were densely aligned. At the end of the treatment, this agent was equally effective against pigmented lesions irrespective of the concentration of KN solution. The distribution of melanin granules returned to normal in the skin of adult hairless dogs. Throughout the present study, there were no histologic abnormalities in the epidermis and the dermis. These results revealed that topical treatment with lower concentrations of KN solutions normalized hyperpigmentation and improved the aged skin structure of hairless dogs. In addition, it was clarified that KN solutions had no adverse effects on the skin of hairless dogs and that this agent was a safe chemical for long-term application.

Corrigendum to: Improved germination of the Australian natives: Hibbertia commutata, Hibbertia amplexicaulis (Dilleniaceae), Chamaescilla corymbosa (Liliaceae), and Leucopogon nutans (Epacridaceae)

Hibbertia commutata Steudel, H. amplexicaulis Steudel, Chamaescilla corymbosa (R.Br.) F.Muell. Ex Benth. and Leucopogon nutans E.Pritzel are four Australian species that are difficult to germinate during mine-site rehabilitation. Laboratory germination trails were conducted to identify dormancy mechanisms and to improve germination response. Treatments applied to all species included scarification and scarification followed by soaking seeds in smoke water (1, 5 or 10%) or gibberellic acid solution (50, 200 or 1000 μM). Additional treatments with kinetin solution (50, 200 or 1000 μM) and smoke water (50 or 100%) were applied to scarified or unscarified seeds of C. corymbosa. Thermal-shock treatment was applied to L. nutans fruit, some of which were subsequently scarified and subjected to both smoke water (10%) and gibberellic-acid solution (1000 μM). Significant germination increases were obtained by using dormancy-breaking treatments on H. commutata (12.8 to 76.0%), H. amplexicaulis (6.8 to 55.1%) and C. corymbosa (48.5 to 86.4%). Scarification alone increased germination of both Hibbertia species, suggesting that these species display a physical seed coat-imposed dormancy mechanism. Germination of H. amplexicaulis was further increased by the application of gibberellic-acid solution, indicating a possible embryo-imposed dormancy mechanism. Scarification followed by the application of smoke water produced the highest germination response for C. corymbosa seeds. Scarification alone did not significantly increase germination, inferring the existence of a smoke-responsive embryo dormancy mechanism. Seeds of L.�nutans, although viable, failed to germinate and are thought to display complex seed coat- and embryo-imposed dormancy mechanisms.

Improved germination of the Australian natives: Hibbertia commutata, Hibbertia amplexicaulis (Dilleniaceae), Chameascilla corymbosa (Liliaceae), and Leucopogon nutans (Epacridaceae)

Hibbertia commutata (Steudel), H. amplexicaulis (Steudel), Chameascilla corymbosa [(R.Br.) F.Muell. Ex Benth.] and Leucopogon nutans (E.Pritzel) are four Australian species that are difficult to germinate during mine-site rehabilitation. Laboratory germination trails were conducted to identify dormancy mechanisms and to improve germination response. Treatments applied to all species included scarification and scarification followed by soaking seeds in smoke water (1, 5 or 10%) or gibberellic acid solution (50, 200 or 1000 μM). Additional treatments with kinetin solution (50, 200 or 1000 μM) and smoke water (50 or 100%) were applied to scarified or unscarified seeds of C. corymbosa. Thermal-shock treatment was applied to L. nutans fruit, some of which were subsequently scarified and subjected to both smoke water (10%) and gibberellic-acid solution (1000 μM). Significant germination increases were obtained by using dormancy-breaking treatments on H. commutata (12.8 to 76.0%), H. amplexicaulis (6.8 to 55.1%) and C. corymbosa (48.5 to 86.4%). Scarification alone increased germination of both Hibbertia species, suggesting that these species display a physical seed coat-imposed dormancy mechanism. Germination of H. amplexicaulis was further increased by the application of gibberellic-acid solution, indicating a possible embryo-imposed dormancy mechanism. Scarification followed by the application of smoke water produced the highest germination response for C. corymbosa seeds. Scarification alone did not significantly increase germination, inferring the existence of a smoke-responsive embryo dormancy mechanism. Seeds of L.�nutans, although viable, failed to germinate and are thought to display complex seed coat- and embryo-imposed dormancy mechanisms.

Effect of kinetin concentration and methods of application on seed germination, yield components, yield and fiber properties of the Egyptian cotton ( Gossypium barbadense)

Two field experiments in 1993 and 1994 as well as a laboratory germination experiment were conducted on the Egyptian cotton cultivar Giza 75 ( Gossypium barbadense) to determine the effect of six concentrations of kinetin (6-furfurylaminopurine) ranging from 0 to 10.0 mg l −1 and three different methods of application: (A) seeds were soaked for 24 h before germination (laboratory experiment) or sowing (field experiment) in solutions of different kinetin concentration, (B) cotton plants were sprayed twice with different kinetin concentrations at 60 and 75 days after sowing (DAS) during the square initiation and the beginning of bolling stages, at volume solution of 480 l ha −1. (C) Seeds were soaked in kinetin solutions before sowing as method A. In addition cotton plants were sprayed twice as method B with the same kinetin concentrations. Kinetin application improved seed viability and seedling vigour as shown by lengths of the hypocotyl, radicle and the entire seedling, as well as seedling fresh weight. Moreover, significant increases were recorded in the number of open bolls/plant, boll weight, lint and seed indices, seed cotton yield/plant, and seed cotton and lint yields/plot. The highest means were obtained at 5 mg kinetin l −1 concentration and under method C of application. Treatments generally, had no significant effects on lint percentage, yield earliness and fiber properties. These results show that, the use of kinetin at 5 mg l −1 for pre-soaking seeds before planting and spraying cotton plants at 60 and 75 DAS with the same concentration could improve cotton germination, seed cotton and lint yields.

The protective action of tannins against glasshouse whitefly in tomato seedlings

The synthesis and accumulation of tannins on tomato seedlings are regulated by environmental factors. The variation in the content of tannins was sufficiently important to bring about the occurrence of significant differences in the numbers of glasshouse whitefly on the seedlings. During a 2-week experiment, the treatments included mechanical wounding (20 prickings per cm2), spraying with kinetin solutions of 10−4 mol/dm3, plant growth regulators, and the atmosphere enrichment to 680 μmol CO2/mol air, the content of tannins being increased by c. 40, 70, 10–45 and 25% above the values obtained in the control. These results were correlated with a decrease in the numbers of insects occurring on the seedlings by c. 35, 45, 8–29 and 18%, respectively. Contrary to the above results the spraying with solutions of abscisic acid, gibberellic acid, and the incubation of plants in an atmosphere containing 170 μmol CO2/mol air, reduced the content of tannins by c. 69, 22 and 25%, respectively. This was reflected in the respective increases by c. 70, 40 and 35% in the numbers of insects occurring on the seedlings. The obtained results suggest that tannins seem to have a dosage-dependent effect on glasshouse whitefly. Decreasing the host plant quality by increasing tannin content may act as an important selective agent limiting the losses brought about by glasshouse whitefly in tomato cultivation.