Types Of Plant Growth Regulators Research Articles

Poinsettia Stem Strength

Lateral branches of poinsettia tend to break from the main stem as plants reach maturity. The cause of poor stem strength is not known; however, suggested factors implicated in poor stem strength are: rate of nitrogen fertilizer used, type of plant growth regulator used, crowding of plants, or stem diameter of the cutting. Four different experiments were conducted to determine if these factors affected stem strength of poinsettia. Experiment 1: `Freedom Red', `Success', `V-17 Angelika Red', `Red Sails', `Nutcracker Red', `Cortez', `Maren', and `Red Splendor' poinsettia were fertilized with 20N–1P0–20K at 75, 75/125, 125/200, or 200 ppm N drip fertigation with zero leachate. Experiment 2: Three plant growth regulators were applied to `Pearl' and `Jolly Red' poinsettias. Experiment 3: `Freedom Red' plants were grown in a 625, 900, 1225, or 1600 cm2 area. Experiment 4: Rooted `Freedom Red' cuttings with stem diameters of 4.5, 5.5, 6.5, or 7.5 mm were used. A force meter was used to determine the strength of each lateral on the main stem of the six replications in each experiment. The lower laterals had the least stem strength and the top lateral had the highest stem strength for all treatments in all experiments. The stem strengths of some cultivars in experiment 1 were stronger at the lower fertilizer rates. Type of plant growth regulator had no significant affect on most poinsettia cultivars. The stem strengths of poinsettias in experiments 3 and 4 varied according to which lateral was measured.

ナフトキノン誘導体, 2-benzimidoy1-3-hydroxy-1,4-naphthoquinone がトマトの生育に及ぼす影響 (第1報)

1) Parthenocarpy of dwarf tomato (cv. Miniature) induced by synthetic naphthoquinone derivatives was investigated. 3-Phenyl-4, 9-dihydronaphth [2, 3-d] isoxazole-4, 9-dione, 2-benzimidoyl-3-hydroxy-1, 4-naphthoquinone, 2-(3--methoxyben-zimidoyl)-3-hydroxy-1, 4-naphthoquinone, 2-(3-pyridylcarbimidoyl)-4 hydroxy-1, 4-naphthoquinone, 2-(4-chlorobenzimidoyl)-3-hydroxy-6, 7-dimethyl-1, 4-naphthoquinone, 6-(or 7-) benzimidoyl-7 (or 6-)-hydroxy-5, 8-dihydroquinoline-5, 8-dione, 2 (N-methylbenzimidoyl)-3-hydroxy-1, 4-naphthoquinone, 2-benzoyl-3-hydroxy-1, 4-naphthoquinoe, 3, 5'-diphenyl-4-oxo-4, 9-dihydronaphth [2, 3-d] isoxazole-9-spiro-', 3', 4'-dioxazole) and 3, 5'-diphenyl-4, 5-dihydro-naphth [2, 1-d] isoxazole-5-spiro-2', 1', 3', 4'-dioxazol-4-one induced clearly parthenocarpic fruits. These compounds are of a new type of plant growth regulators and their chemical structures are different from those already known.2) One of these compounds, 2-benzimidoyl-3-hydroxy-1, 4-naphthoquinone (bendroquinone) was applied to emusculated tomato (cv. Fukuju Ni-Go) flowers. The parthenocarpic fruits showed the same development of fruit as by application of synthetic auxins, HCPA and 4CPA.3) The ovule development of the parthenocarpic fruits was histologically observed. The development of the endothelial cells induced by bendroquinone was not so active as that by HCPA for a period of two weeks after anthesis, but one week later, there was no difference in the development of the pseudoembryo between applications of the two chemicals.4) Bendroquinone isn′t easily soluble in water. It was formulated as 9% wettable powder and applied to tomato (cv. Beiju) flowers in a plastic green house as the setting agent. The fruit set percent and the yield of the first cluster were not so high as compared with the application of HCPA and 4CPA, but in case of the second, the third and the fourth clusters, they were higher. The fruit set percent and the total yield per plant by the application of 200ppm and 300ppm bendroquinone, 200ppm HCPA and 30ppm 4CPA were respectively 73.8% 15.92kg, 78.8% 15.66kg, 73.9% 16.03kg and 60.2% 13.34kg. The puffiness extent of the fruits was slight and there was no phytotoxicity on the plant.5) For induction of parthenocarpy by bendroquinone, the application at earlier stages of flower development was effective as compared with HCPA and 4CPA. The induction of parthenocarpy related closely to the volume and the time retained on the calyx. Therefore, addition of the spray adjuvant would be good for the induction.

Photochemical synthesis of 2-benzimidoyl-3-hydroxy-1,4-naphthoquinone and its analogues. A new type of plant growth regulator

The photochemical synthesis of 2-benzimidoyl-3-hydroxy-1,4-naphthoquinone and related compounds having plant growth regulating activity is described.

The structure of sclerin, a metabolite of sclerotinia libertiana

The structure of sclerin, a new type of plant growth regulator, is shown to be II.