Kasvua hillitsevien aineiden vaikutus pavun taimien kasvuun I. Vaikutuksen riippuvuus käsittelytavasta ja yölämpötilasta

Authors

• Erkki Kaukovirta Helsingin yliopiston puutarhatieteen laitos, Viikki

DOI: https://doi.org/10.23986/afsci.71721

Abstract

The effects of night temperature and growth retardants were studied on the growth of bean, Phaseolus vulgaris var. vulgaris ’July’. The experiments were carried out in growth chambers equipped with 22 »Col White» 80 W-fluorescent tubes providing a light intensity of 5000 lux. The duration of the light period was 14 hours with a temperature of 20—22° C. The night temperatures were 10°, 13° and 18°C. The seeds were pregerminated at 25° C and planted in sand in 4’-plastic pots, 6 seeds per pot. When primary leaves had fully opened the plants were thinned from 6 to 2 per pot and all the plants were treated with growth retardants except those which had been treated before planting. The amount of Cycocel and B-nine in the treatments was 0.1 g and that of Phosfon 0.015 g per two seedlings. The pots were irrigated by modified (WENT 1957) Hoagland solution (0.02 %) daily and if additional watering was needed, deionised water was used. The growth of the seedlings was measured by stem elongation, by increase of leaf area and by accumulation of fresh and dry weight. In the first three experiments this was done 10 days after the primary leaves had fully opened, and in later experiments at the time when the control plants were at the 4-leaf stage in each temperature treatment. The results are given in Tables 2—7 and in Figs 1—3. Stem elongation was distinctly dependent on night temperature. The plants grown in 10° C were significantly shorter in height than those grown in 13° and 18° C. The differences in the heights of the plants between the temperature treatments were somewhat less marked on plants treated with growth retardants. The additional retardation of stem elongation obtained with growth retardants was greater at 18°C than at 13° and 10° C. Plants treated with Phosfon had the shortest stems. On the average, the soil applications of Cycocel and B-nine produced better retardation of stem than spray applications. The interreaction of temperature and method of application was greater on the older seedlings than on the younger ones. The area of leaves and fresh weight of plants were retarded most by the treatments with Phosfon, at the same time but the content of dry matter was highest in plants treated with Phosfon. The effect of Cycocel and B-nine on the area of leaves was dependent on night temperature and on the way of application. Soil drech with Cycocel had a tendency to increase the area of leaves. B-nine spray also increased the area of young seedlings and that of older seedlings at 10° C. DMSO (dimethylsulphoxide) increased the growth retarding effect on spray applications of Cycocel and B-nine. Used in conjunction with B-nine DMSO decreased the dry matter content of seedlings, while it did not have this effect when used with Cycocel.