Tolerance of sunflower (Helianthus annuus L.) to imazethapyr

Abstract

The response of RIMI [imazethapyr-tolerant (T)] sunflower (Helianthus annuus L.) hybrid and the local imazethapyr-sensitive hybrid "Zoltan" (S) was investigated under controlled conditions. Hybrids grown in pots were treated post-emergence with imazethapyr at the two pairs of leaves stage. Visual injury evaluation and vegetative parameters were recorded. ALS (acetolactate synthase) enzyme activity was estimated in vivo 24 h after imazethapyr application. Tolerance level was determined based on the resistance ratio index (ED 50 -herbicide dose causing 50% growth inhibition of T hybrid/ ED 50 of S hybrid). Significant differences were noted between the hybrids in the in vivo ALS activity and vegetative parameters. Indexes of resistance ranged between 5 and 452 for vegetative parameters, whereas the index for ALS activity was 210. The data confirmed the high level of tolerance of the hybrid Rimi as compared with the hybrid Zoltan.

Effect of salinity on germination capacity of laurel (Laurus nobilis L.)

“…This confirms previous studies that suggested that salt stress reduced the biomass of tomato [29], pea [30], Phaseolus [31] and rice [32]. The significant dropped in root and shoot development may be due to toxic effects of NaCl as well as unbalanced nutrient uptake by the seedlings [15].Hence, results found by [33] confirmed this explication.…”

Acetohydroxyacid synthase (AHAS) in vivo assay for screening imidazolinone-resistance in sunflower (Helianthus annuus L.)

“…White et al assessed in vivo AHAS activity on an imazethapyr-resistant sunflower biotype founded in Howard, South Dakota, that showed an I 50 of 200 mM (39-fold more resistant than the susceptible biotype) [30]. Other researchers found that in vivo AHAS inhibition by imazethapyr was 210 folds higher in resistant sunflower hybrid when compared to susceptible hybrid [31]. Previous research on imidazolinone resistant wild sunflower has shown similar results at the enzyme level.…”

Non-Chemical Weed Control for Plant Health and Environment: Ecological Integrated Weed Management (EIWM)

“…The duration of competitive interactions determines the final losses in the growth and development of the plant, and therefore in the crop yield. Planting competitive cultivars at relatively high seeding rates, with controlled application of fertilizers (subsurface banded or point-injected nitrogen), could reduce the negative impacts of weeds on the crop and the amount of weed seeds in the seed bank [68,71]. Cultivars may vary in their competitiveness because weeds reduce the water and nutrient content in the soil profile, making this resource less available, leading the crops into a state of stress, slowing down their growth and development and finally reducing their yield [72].…”