CLONAL GROWTH OF WHITE CLOVER - FACTORS INFLUENCING THE VIABILITY OF AXILLARY BUDS AND THE OUTGROWTH OF A VIABLE BUD TO FORM A BRANCH

The development of an axillary bud of white clover to form a branch de pends on (1) the bud being viable, vegetative and non-dormant, and (2) suitable conditions for outgrowth of the bud. Foraging theory emphasi ses the second of these requirements. Glasshouse studies with white cl over rarely result in a loss of bud viability. In contrast, in field p opulations over 50% of the buds reaching the stage of maturity when br anching can occur are not in a viable, vegetative, non-dormant conditi on. We examined whether non-viability could be induced in a glasshouse experiment by applying treatments in a factorial design. The factors were: defoliation, phosphorus supply, soil moisture status, simulated treading and grass competition. In addition, we measured the effects o f the treatments on the outgrowth of viable buds in order to assess wh ether the same factors were determining viability and outgrowth. Defol iation significantly reduced bud viability (by 44%) but no other facto rs, either singly or in combination, had a significant effect. A great er variety of factors and combinations of factors influenced bud outgr owth; these were defoliation, phosphorus status and interactions invol ving phosphorus and grass; defoliation, phosphorus and soil moisture; and soil moisture, grass and treading. For white clover it is relevant to include the state of the axillary meristem in any model of foragin g. (C) 1996 Annals of Botany Company