CROSS FERTILIZATION OF PEAS.

New Zealand Journal of Agriculture, Volume VI, Issue 1, 15 January 1913, Page 36

CROSS FERTILIZATION OF PEAS.

W. H. Taylor.

To be constantly on the alert to improve strains or to perpetuate a good one is an important, objective of the thoughtful horticulturist. All hybrids are so impregnated with mixed blood that they are ever liable to sport or break off into some variation. Constant inbreeding - or self-fertilization has a weakening effect. The length of time before this weakening becomes very noticeable varies in different varieties, being ruled mainly by their inherent strength or the potency of the blood that had greatest influence in their origin. Sooner or later a variety loses its value, and a successor becomes necessary. New varieties may be obtained either by cross-fertilization or by the natural tendency to sport or vary without cross-fertilization. Crossfertilization may be by artificial or by natural means. By artificial I mean' hand-pollination ; natural means are by pollen conveyed from other flowers by bees and insects. In the former case only a limited number of flowers can be dealt with, and the result must always be doubtful, for there is at all times the sporting tendency to contend against, which renders the most careful hand - fertilizing purely speculative. .The natural means, afford a much wider field, and, certain plans or designs having been carried out, the watcher’s work is confined to selection. 1 am of opinion that most of the new varieties are obtained by selection, and that very little hand-pollination is in reality ever done. Having regard to the various agencies at work, and the limited number of flowers that can be hand-pollinated, I regard such efforts as misdirected. In field or garden culture . the natural agents are continually at work, and a large proportion of the flowers are visited. It only requires an intelligent scheme of planting to be initiated and carried out, so as to force the right kind of pollen on the insects, and there is sure to be. a wide field for selection.

I have had considerable experience and practice in. hand-pollination of plants in glasshouses, and I know it is impossible to be sure of results. As evidence of this uncertainty I may mention that one of the finest primulas in cultivation Sutton’s White Queen obtained from a cross of two crimson varieties. Also, if you save seed from a crimson anemone of hybrid strain you may with reason expect to obtain flowers of all colours from it. I think it will be admitted

that the proper and most profitable way to work, then, is by selection, leaving fertilization to the natural agencies, but influencing their work by supplying pollen from varieties having qualities we wish to amalgamate. New varieties may originate that are not influenced by outside aid, but are the result of the sporting nature above referred to. The agencies that have been at work will, however, matter nothing to the watcher who sees a good new variety, and it may be impossible to determine the origin. . But continued observations carried on over a number of years will at least prove that the natural sporting habit has a strong influence in the process of evolution, and that all personal efforts may prove nugatory.

The varieties . of peas illustrated . are surely conclusive evidence on this point. In 1911 a small quantity of Sherwood was sown for seed-production. The two sports illustrated appeared in the row. They were carefully rogued out —an easy matter, as the plants were far apart in the- row, being thinly sown. The remainder of the seed was saved and planted this spring—l9l2. Again, the same' variations have appeared, which seems to prove an inclination to sport in those directions. The experiment now, unfortunately, ends, all the produce being . required for use on the farm. The illustration shows the two sports and the Sherwood type.

The other variety illustrated —Quite Contentwas sent me by a friend for trial. It is the largest-podded variety I have grown or seen. The pods contain from five to ten peas of large size, but the table quality I have not yet tested. ' The haulm will grow to a height of 10 ft., but as this is an unwieldy height it is not advisable to allow it. It may be given sticks 5 ft. or 6 ft. high, the points of shoots being pinched when they reach the top. Its branching habit will then be strengthened, and the stick be well furnished. It produces a good crop under these conditions, and is an object of interest well worth having in the garden. The plants should not be crowded, 4 in. to 6 in. apart is near enough. Thin to that distance rather than sow too thinly, so as to allow for accidents. This variety would prove unsatisfactory if allowed to lie on the ground.

■ Winter Spraying of Apple-trees .■ —On apple-trees in the orchard at Ruakura Farm of Instruction this season results point to Bordeaux being better for winter use than the lime-sulphur solution. Trees sprayed with the winter formula of the. lime-sulphur solution required the addition of the summer solution to the first application of arsenate of lead for codlin-moth. Trees, on the other hand, sprayed with the 10-10-40 Bordeaux mixture did not require the addition of the summer formula to the arsenate spray.