Reacţia genetică a hibrizilor de porumb (Pioneer) la atacul noului dăunător - Diabrotica virgifera virgifera le Conte – în judeţul Arad

Abstract

A comparative crop of maize hybrids (Pioneer), from different maturity groups (extra-early - PR39D81, early - PR38R92, half-early - PR38A24, PR37D25, PR37M34, PR37W05 and half-lattes - PR35P12, PR36K67), there were tested regarding to point genetic reaction type in rhizotrophic, philotrophic and stigmatrophic interaction of Diabrotica virgifera virgifera Le Conte insects. Regarding mentioned hybrids through plant protection aspect are known follows: Pr38R92 (early) – tolerant at smut Ustilago; PR37D25 – tolerant at Helminthosporium and Ostrinia and resistant at smut Sarosporium; PR37W05 – tolerant at smut Ustilago; regarding the new pest Diabrotica virgifera virgifera Le Conte, there are no references. The experience was made in Sagu locality, Arad district, in 2006 year; the interaction hybrids – pest, analyzed in 15 Jun – 1 Aug period, for larval stage and 15 Jun – 14 Aug, for adult’s stage is pointed through aggressively percents. For establish the hybrids reaction type it was used the scale “resistance source” witch show follow aspects: no aggressively (0), immune hybrid (I); aggressively of 0,1 – 2,0, so 1 - 20% - resistant hybrid (R); aggressively of 2,1 – 4,0, so 21 – 40%, tolerant and middle resistant hybrid (T; MR), and between 4,1 – 9,0 so 41 – 100% - sensitive hybrid (S). The maize hybrids (Pioneer) studied are tolerant to the attack caused by the insect Diabrotica; this reaction was established by the mean value of rhizotrophic, philotrophic and stigmatrophic aggression, namely 29.3-38.5%. This interval is concordant to the limits of “tolerance” amplitude (20-40% attack frequency); the tolerance is “total” or “constant” in semi tardy hybrids, less receptive (PR35 P12 and PR36R67), due to the synergic effect caused by the interaction between characteristics: high-degree root ramification, resistance to drought and long-period vegetation. In the early hybrids (PR39D81, PR38R92, PR38A24, PR37PR37M34, PR37WO5), due to the absence of the specified synergism, the tolerance is “relative” or “inconstant” and it may be lost.