SEED POTATOES

Dominion, Volume 12, Issue 141, 10 March 1919, Page 8

SEED POTATOES

METHODS OF SELECTION I SOME SUGGESTIONS . In an article in tho "Journal of Agriculture" on tho subject of seed potatoes, Mr. W. H. Taylor says:— "The significance ot the old saying 'Like begets like' is doubtless appreciated by every one, yet very few apply tho principles involved to so important-a crop as are potatoes, it is quite jioinmon, experience for a farmer to grow, an-ad-mirable crop for one or two years, and' then a very meagre crop. Bad seasons or something too mysterious to be underBlpod is usually set down as tho cause. "There are'doubtless a number of factors that may be at work to cause failures, and somo of these may be beyond the powers of a grower to alter. It is well known that environment and soil have effect on tubers for seed purposes, but little or nothing is known on that phase of the question as it affects potatogrowing in New' Zealand. That environment does have fjreat effect is proved by the transformation that, takes place, for instance, in the well-known variety Up-to-Date. In the South Island, particularly in Otago, it exhibits its truo form, a half-round with, a somewhat rough skin. Sets obtained from there and' planted in the North Island produce fluke-shaped tubers with a smooth skin.- This alone is evidence of tho need for investigation. In othor ways there is no lack of information or knowledge, and many failures can be distinctly traced to bad practice. It is a general custom to select tho seed tubers from tho crop after it'is'harvested. All sizablo tubors are sold;, the discards are then sorted, and those large enoiwh are kept for seed. . The sets are ell small; although most'of them are fair seed-size, some are really too small, but - would bo good enough if they were of a good 6trajn. "Unfortunately, it is practioally impossible to keep a strain strong by such methods of seed selection. When a crop is lifted some of tho hills give nothing but small tubers, whilo others give a preponderance of small ones with a few large- In both instances thore is evi-. dence of deterioration i)i possibly disease. Hills that are good have but few small tubers. It is -vident that when seed is saved in an indispriminato manner many of the tubers will lie from hills that have shown deterioration, the proportion being dependont on the extent of 6uch deterioration. The longer the process is carried on tho weaker the strain becomes. It must be ovident that this indiscriminate way of saving seed ' tubers ja attended by very grave risks. Even if large or medium-sized tubers were selected in place of small ones thero is an almost undiminishsd risk, for many of tho hills give verjr few tubers, itself a sign of weakening in.the stifim. "If <i strain is to be . kept strong; methods.-other than those just outlined must be adopted. There must bospocial selection, and in many cases special planting of selected sets for seed production. Selection from the growing hills is recognised the world over as the best way to obtain prolific sets. When the tubers have nearly finished growing, but befove the haulm begins to wither, the most "promising-looking hills are lited. Those that come up to tho desired standard, both in the number of tubers and their form, are kept for planting purposes,, discarding thoso below a certain standard. Appearances are sometimes deceitful/ and promising hills are not..always good.. ..Tubers lifted in this way will, of-course, be immature, but it is"ari ficcejitbd'fact' that" such'tubers produce heavier crops than do those that were fully matured.'; Where this cannot bo done great improvement- could •be effected by instituting a process of selection whilo the ripened brop is being lifted, laying aside the tubers of a sufficient number of good hills. Of course, .either plan involves an extra amount of labour, but this is well spent, n.nd improvement in.crops cannot bo'assured without it."