Enhance Growth and Flower Quality of Chrysanthemum indicum L. with Application of Plant Growth Retardants

Ornamental plants are cultivated worldwide. Chrysanthemum is classified as one of the most important cut and potted flowers in most of the countries. The consumer’s expectation is to find small–compact, and full of inflorescences plants. To meet these demands, growers are tending to use plant growth retardants. Three Chrysanthemum indicum L. varieties (‘Smola White’, ‘Arber’ and ‘Vienna White’) were assessed by using four plant growth regulators (PP–Bumper 250 EC; CC–Stabilan SL; MP–Medax Top SC; and PD–Toprex SC). Results indicate that treated plants show significant decrease in the assessed parameters, although in some cases growth could be a variety–dependent factor. It can also be concluded that retardants inhibit chrysanthemum growth. PD treatments greatly inhibited the growth of the plant, and also had a negative effect on inflorescences. In conclusion, the present work strengthens the possibility of using retardants as plant growth inhibitors in Chrysanthemum cultivation.

Effects of Plant Growth Retardants on Development of Poinsettia ”Christmas Feeling” Cultivar

The poinsettias were cultivated years ago as medicinal and ornamental plants, too; but in the recent time are in the light of world flower assortment surprising with new shapes and colors in the cold season. The ornamental values of these plants are given by bracts which can have the same size as foliage leaves or even larger. The tendency of floral industry consists in obtaining high quality ornamental plants with superior marketable price. In these regards, the role of plant growth retardants in regulating the growth of poinsettia is important to obtain healthy, compact bushes and extended decoration period. The aim of the paper is to evaluate the effects of plant growth retardants on poinsettia. Five treatments with different retardants were applied as drench or spray. In the experiment four replicates and a total of 144 poinsettias were used. Treatments with paclobutrazol (60 mg/l sprayed), daminozide (2500 mg/l sprayed) and chlormequat chloride (1000 mg/l sprayed), showed the best results in case of marketability.

​Impact of Foliar Spray of Plant Growth Retardants with Potassium on Growth Traits, Gas Exchange Parameters and Grain Yield in Foxtail Millet (Panicum italicum L.)

Background: Foxtail millet is one of the nutri-cereal foods for the people of semi arid regions. Proper nutrient management and source-sink alteration are major keys for achieving higher productivity in millets. However, potassium is not recommended to foxtail millet and the potential yield is not exploited. And also the study of source-sink alteration in foxtail millet by using plant growth regulators is meager. Methods: An experiment was conducted to study the impact of plant growth retardants viz., chlormequat chloride (CCC) and mepiquat chloride (MC) with the nutrient potassium (K2SO4 - 1%) on growth, gas exchange parameters and grain yield of foxtail millet under rainfed condition. Plant growth retardants with potassium consortium were used as foliar spray at flower initiation stage under field condition. Standard methods were used to measure the plant height, root length, number of leaves, LAD, CGR and grain yield. The photosynthetic rate, transpiration rate and leaf temperature were measured by using the instrument PPS. Result: Foliar spray of CCC (250 ppm) with 1% K2SO4 showed supremacy to enhance crop growth rate, leaf area duration, photosynthetic rate, transpiration rate and grain yield compared to other treatments. However, lowest plant height (100.7 cm) and number of leaves were observed by CCC (250 ppm) alone. Highest photosynthetic rate (26.84) and transpiration rate (17.94) were registered by CCC + K2SO4. Lowest leaf temperature of 34.1ºC was registered by 1% K2SO4 compared to control (35.6°C). CCC with K2SO4 recorded highest LAD value of 46.1 which is on par with K2SO4 alone (45.9). CCC with K2SO4 registered highest grain yield of 2.13 t ha-1 with increased yield of 18.3% over control. However, highest benefit cost ratio of ratio of 2.75 was recorded by 1% K2SO4 alone.

The Dwarfing Effects of Different Plant Growth Retardants on Magnolia wufengensis L.Y. Ma et L. R. Wang

The effects of varieties, concentrations, and number of applications of plant growth retardants (PGRs) on the morphological, physiological, and endogenous hormones of Magnolia wufengensis L.Y. Ma et L. R. Wang were assessed to obtain the most suitable dwarfing protocol for M. wufengensis and to provide theoretical support and technical guidance for the cultivation and promotion of this species. One-year-old M. wufengensis ‘Jiaohong No. 2’ grafted seedlings served as the experimental materials. In the first part of the experiment, three PGRs (uniconazole, paclobutrazol, prohexadione calcium), three concentrations (500, 1000, 1500 ppm), and three applications (one, three, and five applications) were applied in dwarfing experiments to perform L9 (34) orthogonal tests. In the second part of the study, dwarfing experiments were supplemented with different high uniconazole concentrations (0, 1500, 2000, 2500 ppm). Spraying 1500 ppm uniconazole five times achieved the best M. wufengensis dwarfing effect, related indicators of M. wufengensis under this treatment were better than other treatment combinations. Here, M. wufengensis plant height, internode length, scion diameter, and node number were significantly reduced by 56.9%, 62.6%, 72.8%, and 74.4%, respectively, compared with the control group. This treatment increased superoxide dismutase (SOD) activity by 66.0%, peroxidase (POD) activity by 85.0%, soluble protein contents by 43.3%, and soluble sugar contents by 27.6%, and reduced malondialdehyde (MDA) contents by 32.1% in leaves of M. wufengensis compared with the control. The stress resistance of M. wufengensis was enhanced. The treatment also reduced gibberellin (GA3) levels by 73.0%, auxin (IAA) by 58.0%, and zeatin (ZT) by 70.6%, and increased (abscisic acid) ABA by 98.1% in the leaves of M. wufengensis. The uniconazole supplementation experiment also showed that 1500 ppm was the optimal uniconazole concentration. The leaves exhibited abnormalities such as crinkling or adhesion when 2000 or 2500 ppm was applied. Given the importance of morphological indicators and dwarfing for the ornamental value of M. wufengensis, the optimal dwarfing treatment for M. wufengensis was spraying 1500 ppm uniconazole five times.