Effects of Induced Resistance on Disease Severity/Yield Relations in Mildewed Barley

Abstract

Field experiments showed that the treatment of winter barley with microbia! metabolites produced by a Bacillus subtilis strain led to increased yields in spite of a remaining mildew infection. Disease severity yield relations obtained on a single tiller basis for either mildew infection at EC 75 or area under disease progress curve (AUDPC) were negatively correlated for untreated plants (R-= 89%, 94%) while this relation did not exist for inducer-treated ones {R'= 10%, 13%). Despite an increasing infection density, yields of main tillers of inducertreated plants were not decreased. On the other hand area under green leaf area curve (AUGLAC) showed a higher correlation with grain yield {R' = 89%) of inducer-treated plants. Possible explanations for the mitigated damaging efiect of powdery mildew were expected in carbohydrate metabolism, especially carbohydrate formation and translocation. Assimilation rates of flag leaves of inducer-treated barley with similar infection densities to those of untreated plants were increased over a prolonged period and even exceeded those of noninfected ones. In inducer-treated plants the export of "CO; from fiag leaves into ears remained unimpaired by mildew infection and the allocation of assimilates to grains was highest at late stages of grain filling. Obviously plants were stimulated by inducer treatments to compensate for the damaging effect of powdery mildew and to tolerate mildew infection without yield loss. Zusannnenfassuag EinfluBinduzierter Resistenz auf die Befalls-Verlust-Relationen Mehltaubefallener WintergersteIn Freilandversuchen fUhrte die Behandlung von Wintergerste mit mikrobiellen StofTwechselprodukten eines Bacillus ju&»Yw-Stammes trotz eines verbleibenden Restbefalls mit Echtem Mehltau zu Ertragssteigerungen gegeniiber befallsfreien Pflanren. Auf der Basis von Einzelhalm-Untersuchungen zeigte unbehandelte Wintergerste eine negative Korrelaticn zwischen Befall und Ertrag sowohl far den durchschnittlichen Mehltaubefall der oberen beiden Blatter zum EC 75 (R^ = 89%) als auch fflr die Flache unter der Befallskurve (AUDPC, R' = 94%), wahrend eine solche Beziehung fur induriert resistente Pfianzen nicht erkennbar war (R' = 10% bzw. 13%). Trotz steigender Mehltauinfektion war die Ertragsleistung von Haupthalmen induziert resistenter Pflanzen nicht beeintrachtigt. F(lr die Flache unter der Kurve der grttnen Blattflache (AUGLAC) konnte hingegen eine gute Korrelation mit dem Ertrag indtiziert resistenter Pflanzen festegestellt werden. Brklarungsmoglichkeiten fUr die verminderte Ertragswirksamkeit des Echten Mehltaus wurden in einer veranderten Kohlenhydratbildung und-translokation vermutet. Bei etwa gleichem Befall wiesen die Fah-nenbiatter induziert resistenter Gerste gegenuber unbehandelten FHanzen Uber einen langeren Zeitraum hohere COj-Assimilationsraten auf, die auch die der befallsfreien Pflanzen Oberstiegen. Die Verlagerung von '''CO, aus den Fahnenblattem in die Ahren war in induktorbehandelten Pflanzen durch den Mehltaubefall nicht beeintracbtigt und die Einlag...

Effects of foliar applied harpin protein on cotton lint yield, fiber quality, and crop maturity*

“…In field experiments, treatment of winter barley with an elicitor of SAR produced by a Bacillus subtilis strain led to increased yield after infection with Blumeria graminis f.sp. hordei, which could not be accounted for by the reduction in disease severity alone (11). Thus, the possibility of cotton yield enhancement with harpin induced SAR appears to be scientifically based.…”

Induction of systemic protection against rust infection in broad bean by saccharin: effects on plant growth and development

“…These data suggest therefore that induction of systemic resistance to rust infection using saccharin has limited impact on plant growth. This agrees with other work which showed that application of various agents to induce resistance in barley was not associated with reductions in plant growth and yield (Dehne et al ., 1984;Steiner et al ., 1988;Oerke et al ., 1989;Kehlenbeck et al ., 1994;Mitchell & Walters, 1995). It remains to be seen whether induction of resistance in broad bean using saccharin has an effect on yield, because this was not determined in the present work.…”

“…Nevertheless, in a field experiment the overall height of barley was reduced when resistance was induced with methyl jasmonate, although there was a significant increase in yield (Mitchell & Walters, 1995). An increase in yield was also apparent when resistance was induced in barley by application of various agents (Dehne et al ., 1984;Steiner et al ., 1988;Oerke et al ., 1989;Kehlenbeck et al ., 1994). For field application of agents to induce resistance, an important consideration, in addition to the ability to control disease, is the effect on plant growth and yield.…”

Ability of Moderately Halophilic Bacteria to Control Grey Mould Disease on Tomato Fruits

“…This confirms the idea that bacterial isolates unable to form inhibition zones on solid medium are not necessarily incapable of inhibiting disease development in vivo . Bacillus subtilis J9 isolate may assume its antagonistic effect by mainly producing cell‐bound antifungal compounds (Edwards, 1993; Walker et al., 1998) or indirectly by inducing plant resistance mechanisms and/or by nutrient competition (Kehlenbeck et al., 1994; Muninbazi and Bullerman, 1998). The coordinated action of chitinases and proteases, produced by B .…”