R.L. ISON and ANNE E.B. PARSON

School of Crop Sciences, University of Sydney, Australia.

Abstract

Temperature and photoperiod effects on flowering of six accessions of Kenya clover (Trifolium semipilosum) and the white clover (T. repens) cultivar Haifa were investigated. Temperature had the greater control over flowering in T. semipilosum accessions; day/night temperatures greater than 24/19 (Experiment 1) or 27/22°C (Experiment 2) were inimical to flowering. The results do however support a weak quantitative long-day response for T. semipilosum cv. Safari.
Flowering of Haifa was favoured by intermediate daylengths (12 and 14 h but not 10, 16 or 24 h) at lower temperatures. Haifa was consistently the first to flower in the experimental conditions, suggesting a longer juvenile phase for T. semipilosum which may have implications for commercial seed production. This was supported by the discovery that inflorescences of T. semipilosum are principally borne on secondary stolons up to 21 nodes from the primary axis, unlike Haifa where they are borne on primary stolons up to 11 nodes from the primary axis.
Further investigation of the nature of the photoperiod × temperature interaction governing flowering, and mechanisms controlling juvenility in T. semipilosum, are warranted to better determine management practices and delineate sites for seed production.