Biological control in lucerne crops can negatively affect the development of root morphology, forage yield and quality

Abstract

Root diseases of lucerne (Medicago sativa L.) play a significant role in reducing the persistence and productivity of stands; however, the potential of using biological control in lucerne crops has not yet been investigated. Our objectives were to determine the effect of biological crop protection on (i) lucerne plant density and root traits development and (ii) lucerne forage yield and nutritive value in a two-year field experiment. The lucerne stand was managed under three treatments of disease control: an untreated control and spraying with either Albit (hydrolysate of microorganisms containing microelements and poly-beta-hydroxy butyric acid) or Polyversum (mycoparasitic Pythium oligandrum) under five-cut utilization. Application of Albit resulted in a negative yield response, associated with a reduction of root branching, and it also reduced crude protein and increased crude fibre and water-soluble carbohydrates in the second cut of the first year of the experiment. Polyversum increased the percentage of infected plants relative to the control in the last year of the experiment. The study highlights that biological control of lucerne under field conditions may not always be beneficial because of the complex interactions between plant, biological preparation, and environment.

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

“…The results with a single spring application of P. oligandrum in lucerne have not provided positive yield response at the one location investigated so far (Pisarcǐk et al, 2019). For red clover some benefits under an intensive or autumn application regime, in contrast to spring application, have been reported in terms of improved red clover yield and/or root traits (Pisarcǐk et al, 2021). These previous outcomes for red clover highlights potential of P. oligandrum for forage legumes and gives further encouragement to extend the biological control research with treatments including variable timing of applications to lucerne.…”

“…This is especially difficult for perennial forage crops that are utilized over multiple-year growing seasons covering the seeding year and two or three subsequent harvest years. The results with a single spring application of P. oligandrum in lucerne have not provided positive yield response at the one location investigated so far (Pisarcǐk et al, 2019). For red clover some benefits under an intensive or autumn application regime, in contrast to spring application, have been reported in terms of improved red clover yield and/or root traits (Pisarcǐk et al, 2021).…”

“…Öhberg and Bang (2010) confirmed there was a positive yield effect of application of Conithirium minitans prior to seeding, when red clover plants were infected with Sclerotinium trifoliorum. Despite some positive examples of biological control, Pisarcǐk et al (2019) found that biological control under field conditions may not always give beneficial outcomes, in contrast to the results of laboratory or greenhouse experiments, because of complicated interactions between plant, organism/preparation, and environment resulting in general unstable controllling effects from year to year. Although there has been intensive research in biological protection of diseases under controlled conditions, there still remains a lack of field-based studies to provide evidence supporting the economic efficiency of biological control for particular crops, especially for the successive harvest years of perennial forage crops.…”

“…Efficacy of P. oligandrum (strain M1) against Fusarium (F. avenaceum, F. oxysporum, F. culmorum, and F. solani) in red clover stands has been presented (2021; Pisarcǐk et al, 2020) Positive effects on forage yield have been reported in two independent experiments with red clover under treatments with intensive application of P. oligandrum but this improved yield was associated more with plant growth stimulation than from a direct protection against Fusarium (2021; Pisarcǐk et al, 2020). In lucerne, spring application of P. oligandrum was found to provide zero effect on yield and it even increased the proportion of infected plants in the last year of the field experiment (Pisarcǐk et al, 2019). For vetch (Vicia sativa L.), significantly lower effects of biological control than with conventional chemical control have been reported (Georgieva et al, 2020).…”

“…Optimization of the number of applications and dates of application is needed to ensure economic practice in crop protection (Pisarcǐk et al, 2021). This is especially difficult for perennial forage crops that are utilized over multiple-year growing seasons covering the seeding year and two or three subsequent harvest years.…”