The non-essential metalloid arsenic (As) is widely distributed in soil and underground water of many countries. Arsenic contamination is a concern because it creates threat to food security in terms of crop productivity and food safety. Plants exposed to As show morpho-physiological, growth and developmental disorder which altogether result in loss of productivity. At physiological level, As-induced altered biochemistry in chloroplast, mitochondria, peroxisome, endoplasmic reticulum, cell wall, plasma membrane causes reactive oxygen species (ROS) overgeneration which damage cell through disintegrating the structure of lipids, proteins, and DNA. Therefore, plants tolerance to ROS-induced oxidative stress is a vital strategy for enhancing As tolerance in plants. Plants having enhanced antioxidant defense system show greater tolerance to As toxicity. Depending upon plant diversity (As hyperaccumulator/non-hyperaccumulator or As tolerant/susceptible) the mechanisms of As accumulation, absorption or toxicity response may differ. There can be various crop management practices such as exogenous application of nutrients, hormones, antioxidants, osmolytes, signaling molecules, different chelating agents, microbial inoculants, organic amendments etc. can be effective against As toxicity in plants. There is information gap in understanding the mechanism of As-induced response (damage or tolerance response) in plants. This review presents the mechanism of As uptake and accumulation in plants, physiological responses under As stress, As-induced ROS generation and antioxidant defense system response, various approaches for enhancing As tolerance in plants from the available literatures which will make understanding the to date knowledge, knowledge gap and future guideline to be worked out for the development of As tolerant plant cultivars.

Lamiaceae is one of the largest families of aromatic plants and it is characterized by the presence of external glandular structures which produce essential oils highly valued in cosmetics and medicine. Plants of Lavandula latifolia, Mentha piperita, Salvia sclarea, Salvia lavandulifolia, Thymus capitatus, and Thymus mastichina were grown for one year. In order to evaluate the effects of drought stress, plants were subjected to two water treatments (100% ETo and 70% ETo, including the rainfall during the experimental period). At the end of the experiment, the biomass, the essential oil content, and leaf nutrients concentration were assessed for each water treatment and species studied. At the end of the experiment, L. latifolia, M. piperita and T. capitatus plants showed a significant fresh weight reduction under drought stress conditions whereas the other species studied remained unchanged. With respect to dry weight, only L. latifolia plants showed a reduction under water deficit conditions. As far as essential oil content was concerned, L. latifolia and S. sclarea plants had a reduction under water deficit conditions. Leaf nutrient concentration showed different trends between species considering the nutrient assessed. The economic viability of the growth of this species will be dependent on the benefits achieved which are related to yield production obtained and the price accorded for both raw material and the essential oil extracted.

A study was carried out to evaluate the effectiveness of sugar beet extract (SBE) and glycine betaine (GB) in mitigating the adverse effects of drought stress on two maize cultivars. Seeds (caryopses) of two maize cultivars, Sadaf (drought-tolerant) and Sultan (drought-sensitive) were sown in plastic pots. Plants were subjected to different (100%, 75% and 60% field capacity (FC)) water regimes. Then, different levels of SBE (3% and 4%) and GB (3.65 and 3.84 g/L) were applied as a foliar spray after 30 days of water deficit stress. Drought stress significantly decreased plant growth and yield attributes, chlorophyll pigments, while it increased relative membrane permeability (RMP), levels of osmolytes (GB and proline), malondialdehyde (MDA), total phenolics and ascorbic acid as well as the activities of superoxide dismutase (SOD) and peroxidase (POD) enzymes in both maize cultivars. Exogenous application via foliar spray with SBR or GB improved plant growth and yield attributes, chlorophyll pigments, osmolyte concentration, total phenolics, ascorbic acid and the activities of reactive oxygen species (ROS) scavenging enzymes (SOD, POD and catalase; CAT), but reduced leaf RMP and MDA concentration. The results obtained in this study exhibit the role of foliar-applied biostimulants (natural and synthetic compounds) in enhancing the growth and yield of maize cultivars by upregulating the oxidative defense system and osmoprotectant accumulation under water deficit conditions.

The development of intensive horticulture in Almería, with a huge increase in greenhouse surface area, is related to three essential factors: climatic characteristics, groundwater use and mulching sandy soil. The purpose of the present paper is to draw a picture of the integral management of water irrigation in the intensive horticultural systems in the region, by identifying the most significant water resource contributions and alternative water resources. Results indicate that the use of groundwater for the irrigation of horticultural crops in the greenhouses presents a high degree of overexploitation of the aquifers, but due to the continuous search for alternative water resources, such as desalinated and reclaimed water, as well as in-depth knowledge of the integral management of water irrigation through automated fertigation and localized irrigation systems, the current status of the water resources could be sustainable. Moreover, being conscious of the pollution generated by agricultural leachates, the horticultural system of Almería is implementing complementary sustainable systems such as recirculation, cascade cropping systems and phytodepuration for the reuse of the leachate. Considering all these factors, it can be concluded that the intensive horticultural system is on the right path towards respecting the environment and being sustainable in terms of water use.