GROWTH-RESPONSE AND PHOSPHORUS UPTAKE OF RYE WITH LONG AND SHORT ROOTHAIRS - INTERACTIONS WITH MYCORRHIZAL INFECTION

Plant growth and phosphorus (P) uptake of two selections of rye (Secal e cereale L.) differing in length of root hairs, in response to mycorr hizal infection were investigated. Rye plants with short root hairs (S RH) had a greater length of root infected by Glomus intraradices (up t o 32 m pot(-1)) than those with long root hairs (LRH) (up to 10 m pot( -1)). Application of P decreased the percentage of root length infecte d in both selections. In low-P soil, mycorrhizal infection increased s hoot and root P concentration, especially in LRH plants. Generally, LR H had higher shoot dry weight than SRH plants. P uptake was increased both by LRH and by mycorrhizal infection. Differences in specific P up take and P utilization efficiency between SRH and LRH plants were obse rved in nonmycorrhizal plants. With low P supply, P utilization effici ency (dry matter yield per unit of P taken up) of LRH plants increased with time. However, mycorrhizal infection reduced P utilization effic iency, particularly of SRH plants. SRH plants, which were agronomicall y less efficient (i.e. low dry matter yield at low P supply) were more responsive to either mycorrhizal infection or P addition than the LRH plants. No interaction was observed between mycorrhizal infection and root hair length.