Efficacy of Pythium oligandrum on improvement of lucerne yield, root development and disease score under field conditions

Abstract

IntroductionBiological control of root diseases of lucerne (Medicago sativa L.) has potential benefits for stand performance but this remains unsupported by evidence from practical field studies.MethodsIn field experiments at three sites our objectives were to determine the effect of Pythium oligandrum, as spring, autumn and intensive regime treatments on (i) lucerne plant density and root traits development, and (ii) forage yield and forage traits. Lucerne stands were managed under two or three treatments: non-treated control and P. oligandrum applied at two intensities of application under four-cut utilization.Results and discussionUnder relatively dry conditions (annual mean 10°C and <500 mm precipitation) lucerne dry matter yield was significantly reduced by 6%, which could be related to mechanisms of inappropriate stimulation and disturbance of the balance between auxins and ethylene. Under annual precipitation of >500 mm, positive impacts on stand height or fine root mass were observed for the autumn and intensive treatments where positive root response was visible only in alluvial soil. However, these changes did not result in higher yield and probably more applications per year will be needed for significant forage yield improvement. This study highlights the limits of field-scale biological control in which the potential of P. oligandrum for lucerne productivity improvement was realised only under a humid environment or deep alluvial soils, where higher root disease infestation may also be expected.

Seed Treatment Potential for the Improvement of Lucerne Seed Performance and Early Field Growth

“…A similar conclusion was reported by Bradford et al [72], who found a relationship between the mean time of the germination of pepper seeds and the emergence in primed vs. control treatments. Field experiments also enabled the evaluation of root morphology development, as tap-root diameter and lateral root number formation have clear connections with stand productivity and root disease resistance [53,73]. In this regard, the consistent improvement of root branching under potassium permanganate priming can be highlighted.…”