Seed Potatoes

Manawatu Times, Volume 61, Issue 189, 12 August 1936, Page 12

Seed Potatoes

experimenting in new zealand with, light eppeots ' 'FOR INCREASED YIELD The pre-troatinent of seed potatoes by means of continuous illumination as a means of higher production has yet to be the subject of further experimenting in New Zealand in order to ascertain if the reports from Europe of increased yields will apply here. Preliminary experiments were conducted at Palmerston North last season with Sutton Supreme, which is the leading variety in this district. The results did not yield any marked advantageous offect either as a means of hastening maturity or increasing yield. This is not regarded as the final verdict for the treatment, as this season a more regulated experiment under more representative conditions will be conducted. Several years ago it was announced from Northern Europe that a new and very successful method had been evolved for the treatment of seed potatoes, writes E.M.O. in the New Zealand Herald. It was claimed that when the tubers wero kept in continuous illumination, during both day and night, for twenty to thirty days before planting, the yield of potatoes was appreciably increased, and also the maturity of the crop was hastened by ten to twelve days. It was realised that if these claims could be substantiated under local conditions, the method ■would be of considerable value to growers, especially in districts where potatoes are produced for the early market. Accordingly, during the last season, a simple preliminary experiment was conducted at Palmerston North, with the object of discovering how far the treatment was effective. A uniform sample of a certified strain of Sutton Supreme seed potatoes was obtained, and divided into several equal lots. The tubers of one lot—group A—were threaded upon a length of thin wire, and suspended from the roof of a glasshouse at a distance of about 18 inches from a powerful electric light, which was turned on every night. The tubers of another lot —group B—were left in the glasshouse, but were covered to keep out all light. To add further interest to the experiment, tho tubers of a third lot —group C—were put eye-end upward in a shallow box, which was placed in a shaded position in the open. Thus, of the three groups of equal number and weight, A received continuous illumination, B was the control, receiving continuous darkness, and C received the natural conditions of alternative day and night.

No Beneficial Results. The treatments were maintained for 30 days, at the end of which period the tubers were planted whole in the Held. Under all three different conditions of light the seed had. sprouted abundantly, but tho shoots in groups A and C were short, stout and very green, while those in group B, having developed in the dark, were longer and very pale. Care was taken not to damage any shoots in planting and no artificial fertilisers were applied to' tho plots. From this stage no significant difference was observed in the growth of the plants. All emerged from the soil at about the same time, the rate of growth subsequently appeared to be identical in all cases, and no difference was observed in flowerig dates. In all three groups the tops died down at approximately the same time. That is to say, the treatment with continuous light did not apparently have any appreciable effect in hastening development toward maturity. The crop was dug after maturity, and the respective yields measured. The plants of group A produced a total yield of 74.61 b., and the same number of plants if groups B and C produced respectively 71.11 b and 85.41 b.; that is, the first or treated group showed an increased production of 3.51 b. or 5 per cent, over tho untreated or control group B. This increase, however, is not regarded as significant, and may easily have been due to some natural soil fertility factor that had not been taken into account. Thus, the result of the experiment was negative—its value has .been to demonstrate that for the Sutton Supreme variety, and under the particular soil and climate conditions of the trial the pre-treatment of seed potatoes with continuous illumination, as applpied, has no advantageous effect either as a means of hastening maturity or of increasing yield. Tho most interesting part of the trial is tho outstanding increase in yield obtained from Group C, this amounting to 20 per cent over the control'group B. The pre-treatment given to the teed of group C —namely, natural conditions of light and darkness in the open—is actually the method of sprouting recommended by the Department of Agriculture. There are still farmers and others growing domestic supplies of potatoes, however, who consider it sufficient to plant the seed straight from the darkness of the pit or sack. The experiment conduced serves to illustrate again the advantage of sprouting the seed tubers for a month or more in shallow boxes in the open, say, under the shelter of a tree, as an aid in producing the highest yields. Results in Russia. The failure of the continuous light treatment to produce the effects claimed for it seems to require some qualification, especially when the method has given almost spectacular results in Europe. For instance, published records state that in 1934 tho application of this treatment in Russia brought about an increased tuber yield of from 100 per cent, to 150 per cent, and accelerated maturity by one month. It must be remembered, in the first-place, j

that the soil and climate conditions of the particular region may have an influence upon the result, and also that different varieties of potatoes may require slightly different conditions of treatment. Tho actual technique ot the treatment is perhaps a more important consideration. The temperature of the glasshouse, not being subject to control, rose and fell to extremes considerably beyond the limits observed overseas; and moreover, it has since been shown that the threading of tubers on wire, bjr breaking open the tissues, renders them more susceptible to rotting, which naturally reacts on yield and growth. In Europe the seed tubers are now treated with light while simply arranged in layers, although the method of threading was at first recommended and was still in vogue when this trial was planned. With these considerations in mind, it would seem that the result obtained as described above, must not yet be regarded as the final verdict for the •treatment in this country. It is hoped that next season another and better regulated experiment may be conducted under more representative conditions, and that this will enable a definite answer to be driven concerning the value of continuous illumination as a pre-treatment of seed potatoes.