Analysis of Branching in Spring-sown White Lupins ( Lupinus albusL.): The Significance of the Number of Axillary Buds

Plant density and sowing date were shown to affect branching in spring-sown white lupin ( Lupinus albusL.), but the response varied among environments. The patterns of primary and secondary branching in the cv. Lublanc were studied as a function of both the number of axillary buds and the plant growth rate. Field experiments that used a wide range of sowing dates and plant densities to alter plant architecture were conducted over 5 years, and these were supplemented with data from additional glasshouse and growth cabinet experiments. The number of axillary buds on the main stem or primary branches, which determined the potential number of branches, increased linearly with the number of nodes. In situations where all axillary buds did not produce branches, it was found that the number of primary and secondary branches produced was related to the plant growth rate at the beginning of branch elongation. Knowledge of the number of axillary buds improved the analysis of the interaction between cultural practices and environmental conditions on plant architecture. The variability of branching potential among genotypes was discussed.