The elusive role of soil quality in nutrient cycling: a review

peer-reviewedCycling of nutrients, including nitrogen and phosphorus, is one of the ecosystem services we expect agricultural soils to deliver. Nutrient cycling incorporates the reuse of agricultural, industrial and municipal organic residues that, misleadingly, are often referred to as ‘wastes’. The present review disentangles the processes underlying the cycling of nutrients to better understand which soil properties determine the performance of that function. Four processes are identified (i) the capacity to receive nutrients, (ii) the capacity to make and keep nutrients available to crops, (iii) the capacity to support the uptake of nutrients by crops and (iv) the capacity to support their successful removal in harvested crop. Soil properties matter but it is imperative that, as constituents of ‘soil quality’, they should be evaluated in the context of management options and climate and not as ends in their own right. The effect of a soil property may vary depending on the prevailing climatic and hydrologic conditions and on other soil properties. We recognize that individual soil properties may be enhancing one of the processes underlying the cycling of nutrients but simultaneously weakening others. Competing demands on soil properties are even more obvious when considering other soil functions such as primary production, purification and flow regulation of water, climate modification and habitat provision, as shown by examples. Consequently, evaluations of soil properties and management actions need to be site-specific, taking account of local aspects of their suitability and potential challenges.Horizon 202

Salicylic Acid Stimulates Defense Systems in Allium hirtifolium Grown under Water Deficit Stress

Nowadays, the use of the growth regulator salicylic acid for improving a plant’s resistance to environmental stresses such as drought is increasing. The present study investigated the effect of salicylic acid on the physiological traits, antioxidant enzymes, yield, and quality of Allium hirtifolium (shallots) under drought conditions for three years (2016–2017, 2017–2018, and 2018–2019). The experiment was conducted as a split-plot based on a randomized complete block design with four repeats. Irrigation as the main factor in four levels of 100% (full irrigation), 75% and 50% of the plant water requirements with non-irrigation (dryland), and salicylic acid as the sub-factor in four levels of 0, 0.75, and 1 mmol, were the studied factors in this research. The combined analysis of three-year data showed that drought reduced leaf relative water content (RWC), membrane stability index (MSI), chlorophyll content, onion yield, and increased activity of antioxidant enzymes, proline content, tang, and allicin of shallots. Shallot spraying with salicylic acid improved leaf RWC, MSI, chlorophyll content, and onion yield. The highest yield of onion (1427 gr m−2 ) belonged to full irrigation and foliar application of 1 mmol salicylic acid. The lowest yield (419.8 gr m−2 ) belonged to plats with non-irrigation and non-application of salicylic acid. By improving the effective physiological traits in resistance to water deficit, salicylic acid adjusted the effects of water deficit on the yield of shallots. Foliar application of 1 mmol salicylic acid in dryland and irrigation of 50% of the plant water requirement increased onion yield by 15.12% and 29.39%, respectively, compared to the control treatment without salicylic acid

Funneliformis mosseae root colonization affects Anethum graveolens essential oil composition and its efficacy against Colletotrichum nymphaeae

Essential oils have been widely used against a range of plant pathogens due to their antimicrobial effects. Mycorrhization of aromatic plants can enhance the concentration of essential oil components obtained from these plants. This study evaluated the effect of essential oils obtained from dill (Anethum graveolens), inoculated with Funneliformis mosseae, against Colletotrichum nymphaeae, the causal agent of strawberry anthracnose. Dill plants were inoculated with F. mosseae under field conditions, essential oils were extracted from the seeds of inoculated and non-inoculated dill and chemical analysis of their composition was carried out. The efficacy of non-inoculated and inoculated essential oil against C. nymphaeae was evaluated through in vitro experiments. Gas chromatography-mass spectrometry analysis showed that constituents were the same in essential oils extracted from seeds of inoculated and non-inoculated dill plants, however several components increased significantly with inoculated as compared with non inoculated treatments particularly known antimicrobial compounds including limonene and carvone. Essential oil from inoculated plants inhibited mycelium growth (contact and volatile phases) and conidia germination of C. nymphaeae more efficiently than oil from non-inoculated plants. Essential oil from both inoculated and non-inoculated dill plants affected the morphology in a similar manner and deterioration in the morphology was more evident when higher concentrations (500 and 1000 mg/L) were applied. The increase in antimicrobial efficacy due to F. mosseae may have a positive impact on the further development of dill essential oils for plant protection against diseases. This is the first evidence of a positive effect of F. mosseae colonization of dill on the antimicrobial activity of its essential oil against C. nymphaeae

Integrative roles of nitric oxide and hydrogen sulfide in melatonin‐induced tolerance of pepper (Capsicum annuum L.) plants to iron deficiency and salt stress alone or in combination

© 2019 Scandinavian Plant Physiology SocietyThere seems to be no report in the literature on the effect of melatonin (MT) in relieving the detrimental effects of combined application of salt stress (SS) and iron deficiency (ID). Therefore, the effect of MT on the accumulation/synthesis of endogenous nitric oxide (NO) and hydrogen sulphide (H 2 S) and how far these molecules are involved in MT-improved tolerance to the combined application of ID and SS in pepper (Capsicum annuum L) were tested. Hence, two individual trials were set up. The treatments in the first experiment comprised: Control, ID (0.1 mM FeSO 4 ), SS (100 mM NaCl) and ID + SS. The detrimental effects of combined stresses were more prominent than those by either of the single stress, with respect to growth, oxidative stress and antioxidant defense attributes. Single stress or both in combination improved the endogenous H 2 S and NO, and foliar-applied MT (100 µM) led to a further increase in NO and H 2 S levels. In the second experiment, 0.1 mM scavenger of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO) and that of H 2 S, hypotuarine (HT) were applied along with MT to get further evidence whether NO and H 2 S are involved in MT-induced tolerance to ID and SS. MT combined with cPTIO and HT under a single or combined stress showed that NO effect was reversed by the NO scavenger, cPTIO, alone but the H 2 S effect was inhibited by both scavengers. These findings suggested that tolerance to ID and SS induced by MT may be involved in downstream signal crosstalk between NO and H 2 S.Peer reviewedFinal Accepted Versio