Physiological and growth responses of several genotypes of common purslane (Portulaca oleracea L.) under mediterranean semi-arid conditions

Common purslane (Portulaca oleracea L.) is a drought-tolerant weed cultivated for its fresh leaves and stems. In the present study, a field experiment was conducted to determine plant development and photosynthesis of several common purslane genotypes in a high-density planting system. The experiment was carried out according to randomized complete block design with four replications per treatment. Four local populations and two commercial cultivars of common purslane were studied. During the experiment, plant biomass, plant height, leaf relative chlorophyll content (SPAD values), stomatal conductance (gs) and photosynthetic rate (A) were recorded. From the results of our study significant differences in plant height and biomass were observed among the studied genotypes. The lowest height and biomass were found in genotype 'Domokos' whose growth was prostrate to semi-prostrate, whereas all the other genotypes had erect growth. Differences were also observed in physiological parameters. In particular, the relative chlorophyll content (SPAD value) was the highest for genotype 'Domokos', whereas stomatal conductance and photosynthetic rates were the lowest for the same genotype. Biomass yield had also positive and significant correlation with photosynthetic rate and plant height. Our results indicate that the tested genotypes had significant differences in growth habit and physiological parameters. Comparing the tested genotypes, it could be suggested that apart from genotype 'Domokos' which had lower biomass yield due to its growth habit, the rest of the genotypes could be suitable for commercial purposes and proposed as an alternative crop in semi-arid regions of the Mediterranean basin

Efficacy and selectivity of pre- and post-emergence herbicides in chia (Salvia hispanica L.) under mediterranean semi-arid conditions

In the present study, the selectivity and efficacy of several post and pre-emergence herbicides in chia (Salvia hispanica L.) were examined. Field experiments were conducted at two locations with different soil types and environmental conditions. Our results showed that the pre-emergence application of pendimethalin, oxyfluorfen and linuron reduced total weed density by 71-74%, 74-82% and 53-55%, respectively. Despite their high effectiveness against specific weed species, the abovementioned herbicides had a negative effect on plant density and biomass yield. In addition, herbicides bentazon and fluazifopp- butyl which applied post-emergence did not affect significantly plant height and biomass yield. In conclusion, the herbicides linuron, pendimethalin and oyxfluorfen do not seem to be a viable option for weed control in chia crop, whereas the postemergence applied herbicides did not affect significantly plants' growth. Further evaluation of chia tolerance to herbicides is needed under different application rates in order to make safe suggestions for chemical control of weeds. © 2018 Academic Press