CO2 Flux and C Balance due to the Replacement of Bare Soil with Agro-Ecological Service Crops in Mediterranean Environment

Intensive agriculture practices often results in decomposition of organic matter, thus causing soil CO2 emissions. Agro-ecological service crop could be profitably cultivated to improve soil characteristics and reduce CO2 emissions under Mediterranean environment. Two-year field trials were conducted in central Italy. The treatments were three agro-ecological service crops (hairy vetch, oat, and oilseed rape) and a no-service cover. Plant development, soil characteristics, and CO2 emissions were measured. Oat and oilseed rape showed a rapid growth, while hairy vetch started to grow rapidly only after the cold period. Soil CO2 emissions trend was similar among the agro-ecological service crops and tended to decrease during the cold period, then gradually increased until April when warm temperatures were observed. The high soil CO2 emissions and respiration index observed in hairy vetch probably stimulated mineral nutrients, especially nitrogen, to become more available in the soil compared to oat and oilseed rape throughout the decomposition of soil organic matter. These results confirmed that the cultivation of agro-ecological service crops, especially hairy vetch, could represent a suitable strategy for enhancing carbon sequestration and lead to a mitigation of CO2 emissions during the fallow period and could thus contribute to the climate change mitigation

Alleviatory activities in mycorrhizal tobacco plants subjected to increasing chloride in irrigation water

The effects of presence and absence of arbuscular mycorrhizal (AM+ and AM-) fungus (AMF) Glomus intraradices on agronomic and chemical characteristics of field-grown tobacco (Nicotiana tabacum L.) Virginia type (cv. K-326) plants exposed to varying concentrations of chloride 10, 40, 70 and 100 mg Cl L–1 (C1-C4) were studied over two growing seasons (2012-2013). Mycorrhizal plants had significantly higher uptake of nutrients in shoots and number of leaves regardless of intensities of chloride stress. The cured leaves yields of AM+ plants under C2-C4 chloride stressed conditions were higher than AM- plants. Leaf chloride content increased in line with the increase of chloride level, while AMF colonised plants maintained low Cl content. AM+ plants produced tobacco leaves that contained significantly higher quantities of nicotine than AM- plants. AM inoculation ameliorated the chloride stress to some extent. Antioxidant enzymes like superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase as well as non-enzymatic antioxidants (ascorbic acid and glutathione) also exhibited great variation with chloride treatment. Chloride stress caused great alterations in the endogenous levels of growth hormones with abscisic acid showing increment. AMF inoculated plants maintained higher levels of growth hormones and also allayed the negative impact of chloride. The level of 40 mg L–1 in combination with arbuscular mycorrhizal can be considered as the acceptable threshold to avoid adverse effects on Virginia tobacco

Contribution of biochar and arbuscular mycorrhizal fungi to sustainable cultivation of sunflower under semi-arid environment

Arbuscular mycorrhizal (AM) fungi and biochar have been successfully adopted to improve crop growth and yield under water stressed environments, however, to date little evidence of their combined effects has been reported. Field trials were conducted in 2018 and 2019 growing seasons in northern Iran to evaluate how biochar and AM fungi could improve sunflower (Helianthus annuus L.) productivity subjected to reduced irrigation regimes. A randomized complete block design was adopted with the following treatments: three irrigation regimes [no deficit irrigation (NDI), moderate deficit irrigation (MDI) and severe deficit irrigation (SDI) that was calculated as the 50, 30, and 10 % of maximum available water, respectively]; three biochar rates [0 (B0), 2.5 (B2.5) and 5 (B5) t ha−1 of biochar]; and two AM fungi inoculations [inoculated (AM+) and no-inoculated (AM-) plants]. All treatments were replicated three times. Before plowing, biochar (B2.5 and B5) was uniformly distributed on the soil surface to incorporate in the soil profile, while AM fungi (AM+) were distributed in the furrow of sunflower rows before sowing. Biochar and AM fungi were not applied in B0 and AM- treatments, respectively. Sunflower growth rate, pigments, photosynthesis rate and associated aspects, minerals content, antioxidant enzymes, abscisic acid, total phenolics and seed yield were measured. The results showed that growth parameters, radiation use efficiency, leaf pigments and seed yield decreased under irrigation regimes (NDI > MDI > SDI), while malondialdehyde (MDA) and hydrogen peroxide (H2O2) showed opposite trends. The combination AM fungi and biochar enhanced antioxidant enzymes activities, osmoprotectants, nutrient content and relative water content resulting in a significant decrease in oxidative damage in the drought stressed plants. Seed yield ranged from 4.95 to 1.78 t ha−1 and it was increased by the biochar application (+9% and +7% in B2.5 and B5, respectively) and AM fungi inoculation (+21 % in AM+) in all irrigation regimes. Overall, the plant's performance observed in the MDI-B5-AM+ was similar to that in NDI-B0-AM- indicating that AM fungi and biochar allow a reduction of water irrigation while maintaining crop yield. According to results, the combination of AM fungi and biochar rate should be adopted as a water-saving practice for sustainable production of sunflower cultivated in semi-arid environments, even if further studies should be carried out to evaluate their effects on other crops and environments

CO₂ Flux and C Balance due to the Replacement of Bare Soil with Agro-Ecological Service Crops in Mediterranean Environment

Intensive agriculture practices often results in decomposition of organic matter, thus causing soil CO2 emissions. Agro-ecological service crop could be profitably cultivated to improve soil characteristics and reduce CO2 emissions under Mediterranean environment. Two-year field trials were conducted in central Italy. The treatments were three agro-ecological service crops (hairy vetch, oat, and oilseed rape) and a no-service cover. Plant development, soil characteristics, and CO2 emissions were measured. Oat and oilseed rape showed a rapid growth, while hairy vetch started to grow rapidly only after the cold period. Soil CO2 emissions trend was similar among the agro-ecological service crops and tended to decrease during the cold period, then gradually increased until April when warm temperatures were observed. The high soil CO2 emissions and respiration index observed in hairy vetch probably stimulated mineral nutrients, especially nitrogen, to become more available in the soil compared to oat and oilseed rape throughout the decomposition of soil organic matter. These results confirmed that the cultivation of agro-ecological service crops, especially hairy vetch, could represent a suitable strategy for enhancing carbon sequestration and lead to a mitigation of CO2 emissions during the fallow period and could thus contribute to the climate change mitigation

CO2 Flux and C Balance due to the Replacement of Bare Soil with Agro-Ecological Service Crops in Mediterranean Environment

Intensive agriculture practices often results in decomposition of organic matter, thus causing soil CO2 emissions. Agro-ecological service crop could be profitably cultivated to improve soil characteristics and reduce CO2 emissions under Mediterranean environment. Two-year field trials were conducted in central Italy. The treatments were three agro-ecological service crops (hairy vetch, oat, and oilseed rape) and a no-service cover. Plant development, soil characteristics, and CO2 emissions were measured. Oat and oilseed rape showed a rapid growth, while hairy vetch started to grow rapidly only after the cold period. Soil CO2 emissions trend was similar among the agro-ecological service crops and tended to decrease during the cold period, then gradually increased until April when warm temperatures were observed. The high soil CO2 emissions and respiration index observed in hairy vetch probably stimulated mineral nutrients, especially nitrogen, to become more available in the soil compared to oat and oilseed rape throughout the decomposition of soil organic matter. These results confirmed that the cultivation of agro-ecological service crops, especially hairy vetch, could represent a suitable strategy for enhancing carbon sequestration and lead to a mitigation of CO2 emissions during the fallow period and could thus contribute to the climate change mitigation