Changes in the physiological state of peach plants influenced by drought

The article presents experimental data on physiological and biochemical studies of stone fruit culture on the example of Persica vulgaris (Mill.) In the humid subtropics of Russia. The research has been carried out since 2011 in the Laboratory of plant physiology and biochemistry of the Subtropical Scientific Center of the Russian Academy of Sciences on peach varieties of different ripening periods grown in the humid subtropics of Russia. To identify any physiological changes in the body of peach plants during drought, especially in summer, comprehensive diagnostic studies of the water regime (leaf turgidity, determination of the thickness of the leaf blade, water deficiency) and pigment composition are carried out, characterizing the functional state of peach plants. Under unfavorable conditions, promising varieties have a higher ratio of chlorophylls to carotenoids, which confirms their more developed adaptive potential. Studies of this nature have been carried out in order to identify and select resistant peach plants among the studied varieties, which would correspond to the humid region of the Black Sea coast of the Krasnodar Territory. In the subtropical zone of our region, the issue of drought resistance has always been acute, since the impact of negative environmental factors (cool spring, accompanied by drizzling rains and a long summer shortage of air and soil moisture) on peach plants lead to a decrease in productivity and a deterioration in the quality of fruits, which makes their unsuitable and non-transportable. It has been found that among the tested plants, peach varieties Maycrest, Fayet, Larisa have been distinguished by high physiological indicators, such as: low water deficiency – 12,20–14,65%, leaf turgidity ­– 0,18 mm, saturation of leaf tissues within 70,12–79,21%, the content of carotenoids is 0,5–0,7 units, which is a confirming sign of their high resistance to the negative effects of weather conditions in the south of Russia.

Gibberellin in tomato: metabolism, signaling and role in drought responses

The growth-promoting hormone gibberellin (GA) regulates numerous developmental processes throughout the plant life cycle. It also affects plant response to biotic and abiotic stresses. GA metabolism and signaling in tomato (Solanum lycopersicum) have been studied in the last three decades and major components of the pathways were characterized. These include major biosynthesis and catabolism enzymes and signaling components, such as the three GA receptors GIBBERELLIN INSENSITIVE DWARF 1 (GID1) and DELLA protein PROCERA (PRO), the central response suppressor. The role of these components in tomato plant development and response to the environment have been investigated. Cultivated tomato, similar to many other crop plants, are susceptible to water deficiency. Numerous studies on tomato response to drought have been conducted, including the possible role of GA in tomato drought resistance. Most studies showed that reduced levels or activity of GA improves drought tolerance and drought avoidance. This review aims to provide an overview on GA biosynthesis and signaling in tomato, how drought affects these pathways and how changes in GA activity affect tomato plant response to water deficiency. It also presents the potential of using the GA pathway to generate drought-tolerant tomato plants with improved performance under both irrigation and water-limited conditions.

Trends in pluviometric precipitation and climatic water balance in the hydrographic region of Paraguaçu – BA

Trend analysis of hydroclimatic data is essential in the development of water resources management, as it can envisage changes in the pattern of behaviour, helping develop strategies for adaptation in the face of imminent climate change. This study aimed to investigate possible annual and seasonal trends in rainfall and climatological water balance in the hydrographic region of Paraguaçu - BA. From the historical series of precipitation, deficiency and water surpluses, between 1989 and 2018, two analysis scenarios were conducted: the first to verify the annual and seasonal trends of each station, using the traditional Mann-Kendall (MK) methods and Sen’s estimator; and the second for each sub-region of Paraguaçu, by comparing MK with the Innovative Trend Analysis (ITA). The results of the annual series, regardless of the methodology adopted, point to negative trends in rainfall, positive trends in deficit and negative trends in water surplus. Seasonally, in the autumn and winter seasons, generally considered to be drought, there were more trends of increasing rainfall and decreasing water deficiency. A comparison between the MK and ITA models showed that both have similar results for indicating trends in the sub-regions of Paraguaçu. However, the ITA has shown a higher number of significant trends.

VARIABILITY OF MORPHO-BIOLOGICAL TRAITS UNDER THE INFLUENCE OF LOW-FREQUENCY ELECTROMAGNETIC FIELDS ON VEGETATIVE ORGANS OF COTTON

In this article presents the obtained data on research the effect of low-frequency electromagnetic fields on the vegetative organs of cotton in conditions of normal and insufficient water regime. On the basis of the obtained results was revealed that the treatment of the vegetative organs of cotton with EMF will accelerate the growth-development, ripeness and resistance to water deficiency. KEY WORDS: cotton, processing, vegetative organs, low-frequency electromagnetic fields, water supply, plant height, between nodes, cotton boll.

BALANÇO HÍDRICO CLIMATOLÓGICO E CLASSIFICAÇÃO CLIMÁTICA PARA O MUNICÍPIO DE PARANAVAÍ, PARANÁ

The study of climatic conditions of Paranavaí region is necessary due to its importance in the national agricultural scenario. The study aimed to calculate the climatological water balance (CWB) as well as performing the climate classification by the method of Thornthwaite e Mather for the municipality of Paranavaí, Paraná. Data from a historical series from 1975 to 2018 were used. For the calculation of the CWB was adopted the value of 100 mm for the available water capacity (AWC). The municipality studied presentes na annual average of 1523,8 mm precipitation and 1090,62 evapotranspiration. The municipality presented a trend climate o fone month of water deficiency (August) and eleven months of water excess (Setember to July). Regarding climate classification, was found C1dA’a’ climate, characterized as a mesothermic climate, with little or no water deficiency.

Interactions between hydrogen sulfide and rhizobia modulate the physiology and metabolism during water deficiency-induced oxidative defense in soybean

Hydrogen sulphide (H2S), as a new gas signal molecule, participates in the regulation of a variety of abiotic stresses in plants. However, it was unclear how H2S and rhizobia can together to affect the adaptation of soybean to water deficiency. Here, the adaptation mechanism of H2S and rhizobia in soybean to water deficiency was studied. Our results showed that H2S and rhizobia jointly enhanced leaf chlorophyll content, the relative water content (RWC) and caused an increase biomass in soybean under water deficiency. Besides, under water deficiency, H2S enhanced biomass by affecting nodule numbers and nitrogenase activity during the growth of soybean. The expression of soybean nodulation marker genes including early nodulin 40 (GmENOD40), ERF required for nodulation (GmERN), and nodulation inception genes were up-regulated by H2S and rhizobia in nodules. Moreover, the combined effect of H2S and rhizobia were proved to affect the enzyme activities and gene expression level of antioxidant, as well as osmotic protective substance under water deficiency. In addition, the metabolomics results provided that the changes of lipids and lipid-like molecules were remarkably promoted by the combined effect of H2S and rhizobia. Thus, H2S and rhizobia synergistically subsided the oxidative damage by increasing the accumulation of metabolites and strengthening the antioxidant capacity under water deficiency.

CONDITION AND WATER DEFICIENCY OF BALSAMIC POPLAR LEAVES IN THE CONDITIONS OF POLYMETALLIC CONTAMINATION OF THE STERLITAMAK INDUSTRIAL CENTER

The paper presents materials on the water deficiency of leaves in the balsamic poplar in the conditions of polymetallic contamination of the Sterlitamak industrial center. The object of the research was poplar plantations located at different distances from the industrial enterprises of Sterlitamak. As a result, it was revealed that in the conditions of polymetallic contamination of the Sterlitamak industrial center at noon, with an increase in temperature and a decrease in relative humidity, the moisture consumption increases in the balsamic poplar. The maximum water deficit in the daytime is from 13 to 15 hours. In trees in conditions of polymetallic contamination of the SPC, the water consumption during the night hours is not covered by its intake, so the next day the morning hours began with some water shortage. As a result of the conducted studies, it was found that in the conditions of polymetallic pollution of the Sterlitamak industrial center, with the deterioration of the living condition and with a decrease in the proportion of absorbing roots of the balsamic poplar, significant changes in water deficit indicators are noted.

Comparative Transcriptome Profiling Indicated that Leaf Mesophyll and Leaf Vasculature have Different Drought Response Mechanisms in Cassava

Drought stress is one of the major environmental factors that limited crop’s growth and production. Cassava known as a tropical crop that is widely distributed in Sub-Saharan Africa. It has a strong drought tolerance and can grow well under tough environmental conditions. Therefore, understanding how cassava responds to drought stress and coordinates survival and accumulation has great theoretical significance for improving crop drought resistance breeding. Many studies on cassava drought responses mainly focused on the leaf and whole seedling. Nevertheless, how the vasculature plays an important role in plant response to water deficiency remains to be fully elucidated. Here, comparative transcriptome analysis was performed on isolated mesophyll tissue and leaf vein vascular tissue of cassava variety KU50 after mild drought treatment to determine the molecular mechanism behind drought resistance in cassava vasculature. Our results showed that KU50 leaves had increased leaf temperature, with characters of rapidly decreased net photosynthetic rate, stomatal conductance, and transpiration rate in leaves, and the intercellular CO2 concentration accumulated under drought stress. Comparative transcriptome profiling revealed that under drought stress, leaf mesophyll tissue mainly stimulated the biosynthesis of amino acids, glutamic acid metabolism, and starch and sucrose metabolism. In particular, the arginine biosynthesis pathway was significantly enhanced to adapt to the water deficiency in leaf mesophyll tissue. However, in vascular tissue, the response to drought mainly involved ion transmembrane transport, hormone signal transduction, and depolymerization of proteasome. Concretely, ABA signaling and proteasome metabolism, which are involved in ubiquitin regulation, were changed under drought stress in KU50 leaf vascular tissue. Our work highlights that the leaf vasculature and mesophyll in cassava have completely different drought response mechanisms.