Int. J. Appl. Radiat. Isot. Vol. 34. No. 5. pp. 797-800. 1983 0020-708X,83 050797-04503.00/0 Printed in Great Britain Pergamon Press Lid

Investigations on the Effects of Low Dose Irradiation on Different

Bulbous Plants J. B O R S t and I. F E N D R I K 2

tAbteilung i'fir Oekologische Physik der Gesellschaft f'tir Strahlen und Umweltforschung, Mtinchen, F.R.G.

2Institut f'~ Biophysik der Universit~t Hannover, F.R.G.

IN PREVIOUS reports, (t'2) effects of the acute x-irradia- tion of bulbous plants on plant height, number of flowers and fresh- and dry-weight have been de- scribed. As a continuation of this work, further studies were carried out in 1970/80 under the same experimental conditions as before. However the inves- tigation was extended to include two species of Iris. The following bulbous plants were investigated:

Muscari armeniacum T ulipa "Aladdin" Tulipa hybr. "Appeldoorn" Crocus "Remembrance" Crocus "Streaky" Crocus "Yellow" Crocus "Botanical" Scilla sibirica Eranthis hyemalis Galanthus nivalis Iris reticulata Iris danfordiae

The irradiation was carried out with x-rays (300 kV, 0.3 rnm, Cu-Filter) on both dormant bulbs (October, 1979) and on bulbs with the emergence of the first leaf (February 1980). 50, 100, 250, 500 and 1000 rad were applied at a dose rate of 5700 rad/h. The irradiated bulbs were planted in pots with standard soil (50% clay and 50% peat enriched with all nutrients) and were kept at 4°C in a climate chamber until the time of plant irradiation. The bulbs for the plant ir- radiation were similarly treated. After plant ir- radiation both the experimental materials were trans- ferred to a greenhouse under normal conditions. Figure 1 shows how the bulbs and the plants were treated. Four parameters were investigated at the time of flowering: viz. plant height, number of flowers (except Tulipa, since these plants form naturally single flowers only), fresh weight and dry weight. Tables 1-3 show the results of all the plants studied.

In Muscari armeniacum there was an increase of plant height at 100 rad irradiation only, when the dor- mant bulbs were irradiated. On the contrary with plant irradiated material higher number of flowers

and increased fresh- and dry-weight at doses between 250 and 1000 rad. were observed (Table 1).

Tulipa "Aladdin" showed a fresh- and dry-weight increase when the bulbs were irradiated with 500 rad, and an increase in all parameters investigated at all doses applied when the plants were irradiated (Table 1). The highest stimulation (172%) occurred in dry weight at the dose of 1000rad after plant ir- radiation, which dose proved to be damaging for dor- mant bulbs.

In Tulipa hybr. "Appeldoorn" (Table 1) there was no stimulation when bulbs were irradiated, but in- creased plant height, fresh- and dry-weight could be noted after irradiation of plants with moderate or higher doses respectively.

In Crocus "Remembrance" (Table 2) one can detect positive effects in number of flowers with respect to plant irradiation with 1000 rad only. Bulb irradiation revealed in all parameters negative effects in this variety.

A considerable increase in the number of flowers occured in Crocus "Streaky" after both bulb and plant irradiation at all doses applied (as can be seen in Table 2). Bulb irradiation was ineffective regarding the other parameters. Plant irradiation with 100 and 250 rad promoted plant height and irradiation with 500 rad promoted fresh weight in this variety.

As Table 2 for Crocus "Yellow" shows, there was an increase of number of flowers when bulbs and plants were irradiated, but no effect could be noted in the other parameters investigated.

In Crocus "Botanical" (probably the variety "E. A. Bowles') there was a clear increase in fresh- and dry- weight when plants were irradiated but no effect was noticable after bulb irradiation (Table 2l

For Scilla sibirica (Table 1) the irradiation of bulb with doses higher than 100rad was damaging, whereas a pronounced stimulation in terms of all par- ameters occurred when plants were irradiated with low and moderate doses.

In Eranthis hyemalis (Table 3) there was a threefold increase in the number of flowers compared with the controls after irradiation of bulbs with 250 rad. In the

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TABLE 1. Effects of irradiation with x-rays on plant height, number of flowers, fresh weight and dry weight in Muscari armeniacum, Tulipa "'Aladdin", Tulipa hybr. "Apeldoorn" and Scilla sibirica

Irradiation of bulbs Irradiation of plants

Plant Fresh Dry Plant Fresh Dry Plant Dose height No. of weight weight height No. of weight weight name (rad) (cm) flowers (g) (g) (cm) flowers (g) (g)

Muscari flrmeniacum

Control 16.6 3.0 14.3 1.3 20.5 2.5 13.3 1.0 % of control % of control

50 103 96 103 103 98 111 99 113 100 115" 89 106 100 94 101 96 110 250 106 92 100 100 95 131" 112 133" 500 99 110 99 99 94 105 109 122"

1000 104 103 106 104 102 118" 116" 126"

Tulipa "Aladdin"

Control 35.1 13.3 1.5 32.6 13.6 1.4 % of control % ofcon~ol

50 98 99 8 6 126" 132" 129" 100 93 93 82 126" 135" 138" 250 96 101 91 120" I13" 130" 500 94 119" 120" 120" 124" 142"

I000 79* 78* 102 119" 130" 172"

Tulipa hybr. "Apeldoorn"

Control 34.9 34.6 2.9 28.9 28.4 2.4 % of control ~ ofcon~ol

50 100 103 95 I11 114 106 100 100 104 97 109 107 103 250 97 100 103 115", 116" 113" 500 88 92 95 107 112 119"

1000 69* 72* 86 108 118" 136"

Scilla sibirica

Control 14.9 4.6 ~6 0.5 12.8 4.0 3.9 0.5 % of control % of control

50 95 103 98 98 91 116" 111 106" I00 106 105 112 112 115" 115" 129" 139" 250 82* 102 79* 87 109 132" 134" 133" 500 51" 71 54* 63* 92 119" 102 96

1000 39* 60* 38* 47 85* 112 97 93

* Significant at P < 5%. Increased values are set in bold.

Low dose x-irradiation effects on bulbous plants 799

TABLE 2. Effects of irradiation with x-rays on plant height, number of flowers, fresh weight and dry weight in Crocus "Remembrance", "Streaky ~, "Yellow" and "Botanical"

Irradiation of bulbs Irradiation of plants

Plant Fresh Dry Plant Fresh Dry Plant Dose height No. of weight weight height No. of weight weight name (rad) (cm) flowers (g) (g) (cm) flowers (g) (g)

Cro¢I~5 "Remembrance"

Control 8.4 1.2 4.9 1.0 8.2 1.0 4.5 1.0 °//o of con~ol % of control

50 103 113 109 91 105 121" 89 99 100 100 90 104 86 110 101 96 99 250 91 73* 84* 84* 104 105 I01 103 500 82* 61" 66* 65* 113 100 109 103

1000 94 76* 86 89 100 116 101 104

CROCUS "Streaky"

Control 5.3 1.5 4.9 1.0 5.1 1.2 6.0 1.4 % ofcon~ol °/o of control

50 105 281" 99 108 I00 500* llO 85 I00 95 163" 85 99 144" 400* 109 89 250 105 288* 97 104 127" 1200" 110 97 500 102 206* 94 92 107 1000" 121" 94

1000 104 138" 109 114 102 400* I01 91

Crocus "Yellow"

Control 7.1 1.2 3~ 0.8 9.3 1.0 3~ 0.7 %ofcon~ol %ofcontrol

50 92 109 I00 94 106 207* I07 II0 I00 97 91 98 89 86 130" 95 90 250 106 125" 99 I00 99 153" 97 107 500 94 94 96 85 96 98 94 91 I000 93 162" 96 94 98 140" 105 103

Crocus "Botanical"

Control 14D 4.5 33 0.5 14D 3.8 3.0 0.5 % of con~ol % of control

50 107 92 93 95 10l 10l 128" 116" I00 I05 96 94 94 105 lOl 119" 112" 250 106 97 96 99 104 I05 143" 125" 500 103 94 87 94 101 I00 134" 123" I000 97 101 89 102 IOl 102 142" 123"

* Significant at P < 5%. Increased values are set in bold.

800 J. Bors and I. Fendrik

TASLE 3. Effects of irradiation with x-rays on plant height, number of flowers, fresh weight and dry weight in Eranthis hyemalis, Galanthus nivalis, Iris danfordiae and Iris reticulata

Irradiation of bulbs Irradiation of plants

Plant Fresh Dry Plant Fresh Dry Plant Dose height No. of weight weight height No. of weight weight name (tad) (cm) flowers (g) (g) (cm) flowers (g) (g)

Eranthis hyemalis

Control 9.1 0.25 0.66 0.09 9.0 0.10 0.56 0.09 % of control % of control

50 95 I00 98 96 121" I00 88 89 100 92 100 84 84 l l0 100 81" 84 250 84 300* 96 92 125" 100 l lg* 127" 500 102 100 100 93 149" 200* 126" 144"

1000 87 100 55* 61" 149" 200* 118" 137"

Galanthus nir:alis

Control 16.0 1.0 1.30 1.14 15.7 1.0 1.20 0.13 % of control % of control

50 112 88 106 106 117" 130" 146" 141" 100 92 84 85 88 117" 138" 130" 134" 250 91 87 88 87 104 120" 113 120" 500 70* 77* 60* 65* 97 115 109 115

I000 43* 46* 35* 42* 98 105 114 122"

Iris reticulata

Control 18.1 1.0 4.0 0.38 19.1 1.0 3.8 0.46 % of control % of con~ol

50 111 100 101 104 108 124" 107 126" lO0 102 95 95 97 98 115" 94 104 250 99 90 87 92 120" 129" 126" 129" 500 86 95 78* 88 110 129" 115" 120"

1000 47* 100 64* 70* 97 129" 104 103

Iris danfordiae

Control 28.1 1.30 1.80 0.26 30.2 ~95 1.80 0.26 % of control % of control

50 98 138" 107 104 106 83 107 105 100 99 125" 109 106 104 100 102 106 250 99 88 110 105 102 200* 105 106 500 76* 75* 76* 77* 91 167" 97 101

1000 47* 175" 63* 68* 86 100 97 97

* Significant at P < 5%. Increased values are set in bold.

other parameters there was in general no positive effect. In fact a negative effect was seen in terms of fresh- and dry-weight when bulbs were irradiated with 1000rad. On the other hand plant irradiation pro- duced a marked increase in all parameters investi- gated.

Higher doses of bulb irradiation than 250rad caused damage in Galanthus nivalis in relation to all parameters (Table 3). In the test material of plant irradiation, a remarkable stimulation in growth par- ameters and in number of flowers per plant were seen. With the exception of dry weight at 1000 tad, the positive effects were induced at low and moderate doses in this species.

As will be apparent from Table 3, there was no st imulat ion in Iris reticulata when bulbs were irra- diated but higher doses led to growth retardation. In contras t to this s i tuat ion there was an increase in all parameters when plants were irradiated.

Table 3 shows that for Iris danfordiae, bulb ir-

radiation was unfavorable in terms of all parameters with the exception of number of flowers at 1000 rad. Numbers of flowers was the only parameter which could have been influenced positively when plants of this species were irradiated with doses of 250 and 500 tad.

In agreement with previous experiments, the analy- sis of the reported data reveals the occurrence of de- creasing effects when bulbs were irradiated compared with irradiation of whole plants. Probably this could be due to the longer post i rradiat ion time between bulb irradiation and evaluation of data. Finally one could draw the valid generalisation that irradiation in an active stage is more effective in bringing about s t imulatory results than i rradiat ion of dormant bulbs.

References

1. Bogs J. and F~-~OxxK I. Stint Newsl. No. 10, p. 6 (1976). 2. Bogs J. and F~qoglK I. Stint Newsl. No. 11 (1978).