WHITE CLOVER STRAINS

New Zealand Herald, Volume LXX, Issue 21450, 25 March 1933, Page 17

WHITE CLOVER STRAINS

NEW ZEALAND TYPES A VALUABLE ASSET A review of white clover trials in New Zealand, contributed to the Journal of Agriculture by Messrs. E. Bruce Levy and L. W. Gorman, of the Plant Research Station, confirms the fact that the Dominion has a distinctly valuable asset in its strains of this species. The experiments they mention have completed a three-year test and the investigators state that from commencement to finalisation the New Zealand No. 1 white clover type was outstanding in yield, long seasonal spread of growth and persistency, and that no other type of clover maintained itself so free of volunteer grasses and weeds. In a broadcast in which the clover was scythed at a 6in. to Bin. stage to the virtual exclusion of reseeding on the area, high soil fertility was maintained by periodic top-dressing with superphosphate. It is suggested that this treatment may have favoured the New Zealand No. 1 type over all others of local and imported origin because of the robust growth and strong, competitive nature of the type, as against one, such as Kentish wild white, which is readily smothered if competitive growth is allowed to become too tall. Then again, free-seeding, lionpersistent types are at a disadvantage under periodical cutting which prevents reseeding and tall growth which inhibits le-establishment from shed seed. Nevertheless, the experience of the New Zealand No 1 type is now considerable and where plots undergoing certification trial during the past 12 months have been grazed with sheep it is said to have been outstanding. Certification Standard During the Inst two years of their currency the trials were conducted largely to determine certification standards which will henceforth apply to white clover seed certified and sealed by the Department of Agriculture as New Zealand certified white clover. Lines dominantly New Zealand No. 1 type were regarded as up to mother-seed standard, and plots dominantly New Zealand No. 2 with some New Zealand No. 1 have constituted the New Zealand certified permanent pasture standard. Ordinary New Zealand white clover, while considerably better than imported Dutch types, was considered below certification standard and wore therefore placed in the rejected class. Having regard to production, its seasonal spread and persistency against weed and grass competition, no imported Dutch lines approached certification standard. Approximately two-thirds of the Kentish wUd white lines included in tho trials reached permanent-pasture standard, but no line of this type reached mother-seed standard. Had the trials been conducted under close grazing it is thought probable that the Kentish wild white strains might have scored a better place, but the investigators entertain little doubt that the results are truly representative under New Zealand conditions at least.

The superiority of New Zealand certified white clover is attributed to the proportion of No. 1 strain it contains, tho marked success and good name which New Zealand white clover enjoys overseas being attributed to tho presence in lines shipped oi a proportion at least of the No. 1 or No. 2 types. In the plot work described lines which three years ago contained but a trace of No. 1 wero dominantly this typo at the end of the third year, tho poorer lower-growing types being swamped out, by the more aggressive No. 1. Of 181 lines which were dominantly ordinary New Zealand type at the commencement of the test, but which contained a trace of No. 1 or No. 2, 47 lines reached mother-seed standard, and 80 attained permanent-pasture standard. Lines of ordinary New Zealand, plus a trace of type No. 1, maintained their superiority, approaching type No. 1 itself at the end of the three years, whereas lines of ordinary, having no trace of type No. 1 in them, fell very low by the end of the third year. Value of Persistency Tho trials, say the investigators, have pressed homo forcibly tho value of persistency coupled with high production in a strain. In the case of the New Zealand No. 1 white clover, the plots at the end of tho three years wore 100 per cent clover and at no stage did they contain weeds or volunteer grass growth. Low persistency in a strain means death to the species and a corresponding opening-lip of the sward, leading to weed and volunteer grass invasion. The inability of the Kentish wild white lines to dominate their respective plots 'is attributed to low production rather than to low persistency. It is almost impossible, the writers say, to place a value on what white clover means to the pastoral industry of New Zealand. Pride of place rests between white clover and perennial ryegrass. Viewing the pastures as they exist to-day, and considering tho fact of 60 much ryegrass of poor type having been sown, they contend that white clover is contributing year in and year out the greater proportion of the food of tho pasture. While this state- probably should not exist in tho ideally-constituted pasture, tlio fact that it is so cannot be gainsaid. The substitution of the present white clover typo by a still higher-producing type —the New Zealand certified type — and associating this with a good ryegrass type together with the balancing of these by suitable manuring, is considered to be basic to a large forward movement in grassland improvement.