Root morphology and architecture, and internal phosphate use efficiency, in related white clover cultivars of different ages

Abstract

Root morphology and architecture were determined for four related white clover (Trifolium repens L.) cultivars—Huia, Pitau, Kopu II and Mainstay, released 57, 36, 15 years and 1 year ago, respectively. The plants were grown in soil maintained at a range of available phosphate (P) levels in a glasshouse pot experiment. Root samples for analysis were obtained from plants growing in the 17 and 62 mg P kg−1 soil treatments. There were no statistically significant (P < 0.05) effects of cultivar age or soil P level on root morphology or architecture. The inherently efficient herringbone branching pattern of white clover root systems has apparently been able to support ongoing improvements in shoot system performance during cultivar development, without changing. There was a significant increase in shoot dry weight yields per unit plant P absorbed, as cultivar age decreased. This is evidence that repeated selection for shoot traits has resulted in an increase in internal P-use efficiency.