Mycorrhizal impact on competitive relationships and yield parameters in Phaseolus vulgaris L. - weed mixtures.

Arbuscular mycorrhizal fungi (AMF) are known to improve plant growth and nutrition and therefore are likely to affect the competitive relationships between crops and weeds. In this study, we evaluated whether AMF (Funneliformis mosseae, Rhizoglomus fasciculatum, Rhizoglomus intraradices) change plant competition between Phaseolus vulgaris and the weeds Solanum nigrum L., Digitaria sanguinalis L., and Ipomoea purpurea L. Mycorrhizal colonization, aggressivity index, photosynthetic rates, and yield parameters were measured. While the presence of AMF reduced the total biomass of D. sanguinalis and S. nigrum when grown in competition with P. vulgaris, it increased the total biomass of I. purpurea when grown with P. vulgaris. Significantly, elevated mycorrhizal growth responses (38-44%) improved the competitive ability of I. purpurea. In contrast, the competitive ability of S. nigrum was increased only when plants colonized by R. intraradices. The total protein content of P. vulgaris pods when in competition was negatively affected by AMF, thus leading to low nutritional quality. The results suggest that AMF have the potential to affect the outcome of weed-P. vulgaris competition. We demonstrate that not only colonization with AMF but also AMF species can affect the competitive relationships between crops and weeds, and thus, AMF represent key soil organisms to be taken into account in sustainable weed management strategies.

Study the effect of 24-epibrassinolide application on the Cu/Zn-SOD expression and tolerance to drought stress in common bean.

To study the possibility of increasing the drought tolerance of common bean with the exogenous application of 24-epibrassinolide (EBL), an experiment was conducted in 2016 and 2017. In this experiment, two irrigation levels (optimal irrigation and drought stress) were applied to the main plots and two common bean genotypes (Kusha cultivar and COS16 genotype) and four EBL concentrations (0, 2, 4, and 6 µM) were allocated to sub-plots as factorial. In the flowering stage, drought stress was applied and plants were sprayed with EBL. The results showed that drought stress reduced relative water content (RWC) and increased proline content, malondialdehyde (MDA) content, and antioxidant enzymes activity. However, exogenous application of EBL reduced the seed yield loss and increased the drought stress tolerance in both common bean genotypes by decreasing the MDA content and increasing the RWC, proline content, antioxidant enzymes activity, and nitrate reductase activity. It can be concluded that foliar spray of 4 µM EBL as the best concentration may increase the seed yield and enhance the drought stress tolerance of common bean. Also, Cu/Zn-SOD was up-regulated in response to the drought stress and exogenous EBL. The COS16 genotype showed better response to the drought stress and exogenous EBL than the Kusha cultivar, because of the higher up-regulation of Cu/Zn-SOD in this genotype compared to the Kusha cultivar. Therefore, EBL can be used as a plant growth regulator to enhance drought stress tolerance and minimize the seed yield loss of common bean caused by water deficit.

Weed community changes in saffron+chickpea intercropping under different irrigation management.

Saffron (Crocus sativus L.) is among the world's most expensive crops; nevertheless, it struggles to compete with weeds. Non-chemical farming practices, such as intercropping and reduced irrigation, can help to decrease weed problems. Therefore, this study aimed to evaluate the changes in the weed density, biomass and weed diversity under saffron-chickpea intercropping system with two irrigation regimes. The study's treatments included two irrigation regimes, namely one-time irrigation and conventional irrigation (carried out four times from October through May), and six planting ratios of saffron and chickpea, namely saffron sole-crop (C1), chickpea sole-crop (C2) in eight rows, 1:1 (C3), 2:2 (C4), 2:1 (C5), and 3:1 (C6)] as main and sub-plots, respectively. The result showed that the conventional irrigation regimes increased weed diversity, however, it didn't affect the Pielou index. Intercropping ratios decreased weed diversity compared to saffron and chickpea mono-cropping systems. The interaction effect of treatments was significant for weed density and weed biomass. In most intercropping ratios, weed density and weed biomass decreased under one-time irrigation regimes. The lowest values for weed density and biomass were observed with an average of 15.5 plants/m2 and 37.51 g/m2, respectively, under the one-time irrigation regime with C4 intercropping systems. This intercropping system did not show a significant difference with C3. Overall, the results indicate that a one-time irrigation regime and intercropping with chickpea, specifically with a 1:1 saffron-chickpea ratio (C3) and a 2:2 saffron-chickpea ratio (C4), could be effective strategies for weed management in saffron in semiarid cropping systems.