S U M M A R YThe frost hardiness of 5-month-old seedlings of 12 white clover cultivars was examined at -4 , -8 , -1 2 and -1 6°C and in a subsequent study the frost hardiness of 6-month-old seedlings of 190 experimental lines and 23 cultivars and ecotypes was determined at -12°C. There were large differences among cultivars and lines in frost tolerance based on the percentage of plants damaged and the percentage of leaves killed. The most frost-hardy were the cultivars Podkowa and Undrom and ecotypes collected from Kaikoura and Nelson Lakes. There was no significant, correlation between the percentage germination of cultivars at 4 °C and their subsequent frost hardiness.Large-leaved, erect cultivars tended to be more frost sensitive than small-leaved, prostrate cultivars. Frost-tolerant cultivars and lines tended to be acyanogenic. Selection for low winter growth did not increase frost tolerance. However, lines derived from crosses between genotypes of cold-hardy lines selected for rapid germination at 4 °C were more frost-hardy than lines from genotypes selected in a similar way that had been crossed with unselected Huia genotypes.

A range of shrubs was evaluated as potential sources of forage for grazing animals. Shrubs were established in rows in hill pastures near Woodville. Nine"true" shrubs, and two erectgrasses, pampas grass (Cortaderia selloana), and toetoe (C. fulvida) were evaluated. The true shrubs were:Chamaecytisus palmensis, tagasaste: Medicago arborea, tree medic; Ulex europaeus, gorse (two variants: wild gorse and short-spined gorse); Cytisus scoparius, broom; Robinia pseudoacacia, black locust; Leptospermumscoparium, manuka; Cassinia leptophylla, tauhinu; and Ceanothus griseus, ceanothus. Digestibility of shrubs was assessed by in situ (nylon bag) digestion in cows' rumens, and by in vitro (cell ulase) methods. The two methods ranked most forages similarly, but some inconsistencies did occur. Tree medic and tagasaste were highly digestible (71-73% estimated in vivo DM digestibility). Manuka, pampas, and toetoe had low digestibility (48-56%). Stem material was less digestible than leaf. Digestibility was strongly related to combinations of functions of cell wall content, degree of lignification, and degree of silicification. Oesophageal-fistulatedsheep and goats were allowed to graze each of the shrub species in the field. They selected a diet 5--6% units more digestible than the average of the forage on offer.

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The analysis of Kennedy et al. (1985) was applied to 150 individuals from each of six plots containing mixtures of the perennial ryegrass (Lolium perenne L.) cultivar Grasslands Nui and the resident ryegrass population at Rawhiti, Central Wairarapa, New Zealand. Four alleles (A, B, C and D) were identified at the phosphoglucoisomerase-2 allozyme locus in the two ryegrass populations. Using the maximum likelihood method, non-linear models were fitted to calculate the percentage contribution of Grasslands Nui to the mixtures. The contribution of Grasslands Nui to the six evaluation plots ranged from 5 to 44%, with S.

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