BA: 

19930321853

ET: 

Watermelon seed germination. 1. Effects of light, temperature and osmotica.

AU: 

Thanos, C. A.; Mitrakos, K.

AA: 

Institute of General Botany, University of Athens, 15784 Athens, Greece.

SO: 

Seed Science Research, 1992, Vol.2, No.3, pp.155-162, 20 ref.

AB: 

Seeds of watermelon cv. Sugar Baby germinated optimally in the dark throughout the temperature range from 20 deg to 40 deg C. Germination was inhibited by continuous (c) irradiation with far-red (FR), blue or white incandescent light; short pulses were ineffective. Intermittent FR could fully substitute for cFR; the effect of alternating red and FR pulses during 30-min dark cycles depended upon the timing of the illuminations within each cycle. It is concluded that germination in this species is controlled by the low-energy reaction of phytochrome. However, continuous and intermittent red light partially reduced germinability. Opening the seed coat at the radicle end enhanced germination in the dark and reduced photosensitivity towards FR. The outer, lignified part of the testa exerted a mechanically restrictive force upon the expanding radicle; this force was estimated to be equivalent to 0.3 MPa. The kinetics, at 25 deg in the dark, of the time course of germination and the escape from the inhibitory effects of cFR and osmoticum (0.5 M mannitol) were all sigmoid curves, which, upon transformation to normal distributions, had different means, but statistically similar variances. The cFR-irreversible activation of germination by phytochrome and the mannitol-irreversible onset of radicle elongation preceded radicle protrusion (mean at 32 h, 25 deg ) by 8 and 6 h, respectively. It is concluded that activation of germination in watermelon takes place during the second, stationary phase of imbibition (20-30 h after sowing at 25 deg ).

DE: 

Watermelons; seeds; germination; light; temperature; plant physiology; Phytochrome; metabolism; far red light; treatment; osmotic pretreatment; seed treatment; mannitol; water relations; blue light; white light; red light; tropical fruits; fruit crops

OD: 

Citrullus lanatus

UP: 

Citrullus; Cucurbitaceae; Violales; dicotyledons; angiosperms; Spermatophyta; plants

IS: 

0960-2585

CC: 

FF060;
FF160;
FF900

RY: 

69-65-8

LA: 

English

DT: 

Journal article

SC: 

Horticultural Abstracts; Seed Abstracts; Crop Physiology Abstracts