Drought effects on the mineral composition of the leaves of Actinidia species

Against the background of global climate change, drought stress has become one of the environmental limiting factors that can significantly influence the growth and development of crop plants. Drought stress conditions also cause changes in plant physiological and metabolic processes. The influence of soil drought on the mineral composition of the leaves of two Actinidia species with С3-type photosynthesis, namely, Actinidia argutа (Siebold & Zucc.) Planch. ex Miq. cultivar ‘Taezhny Dar’ and Actinidia kolomikta (Maxim. & Rupr.) Maxim. cultivar ‘Narodnaya’, was studied through energy dispersive spectrometry. The investigations were carried out during 2020 to 2021 at the Department of Genofonde and Bioresources of Plants, Federal Scientific Center for Horticulture, Moscow. The present research revealed that actinidia leaves contained the following major elements: K (11.19 mass% to 13.84 mass%), Ca (7.83% to 12.08 mass%), Cl (6.20 mass% to 7.33 mass%), and Mg (2.98 mass% to 3.44 mass%). Low values were recorded for Mo (1.19 mass% to 4.49 mass%) and P (0.83 mass% to 1.25 mass%). In both species, the mineral elements K and Ca were present at high levels. A positive correlation was observed between Mg–P, K–Mn, Mn–Se, Cu-Se, P–Si, Na–Mo, and Si–Mn in the leaves of A. argutа and between Cl–Ca, Mo; P–Si, Mo; and K–Ca in the leaves of A. kolomikta. Under stress conditions, the ratios of K/Ca and K/P declined to 0.9 and 6.3, respectively, whereas those of K/Cl, K/Mg, and K/Mo increased to 3.8, 4.4, and 2.7, respectively. The present studies confirmed that actinidia leaves contained high concentrations of minerals, especially K, Ca, P, and Mg, and that the accumulation of mineral elements in actinidia plant leaves under drought conditions varied depending on the species.

Biochemical and cytological features of onion bulbs and leaves collected from various ecogeographical origins

Against the background of global climate change, drought stress has become one of the environmental limiting factors that can significantly influence the growth and development of crop plants. Drought stress conditions also cause changes in plant physiological and metabolic processes. The influence of soil drought on the mineral composition of the leaves of two Actinidia species with С3-type photosynthesis, namely, Actinidia argutа (Siebold & Zucc.) Planch. ex Miq. cultivar ‘Taezhny Dar’ and Actinidia kolomikta (Maxim. & Rupr.) Maxim. cultivar ‘Narodnaya’, was studied through energy dispersive spectrometry. The investigations were carried out during 2020 to 2021 at the Department of Genofonde and Bioresources of Plants, Federal Scientific Center for Horticulture, Moscow. The present research revealed that actinidia leaves contained the following major elements: K (11.19 mass% to 13.84 mass%), Ca (7.83% to 12.08 mass%), Cl (6.20 mass% to 7.33 mass%), and Mg (2.98 mass% to 3.44 mass%). Low values were recorded for Mo (1.19 mass% to 4.49 mass%) and P (0.83 mass% to 1.25 mass%). In both species, the mineral elements K and Ca were present at high levels. A positive correlation was observed between Mg–P, K–Mn, Mn–Se, Cu-Se, P–Si, Na–Mo, and Si–Mn in the leaves of A. argutа and between Cl–Ca, Mo; P–Si, Mo; and K–Ca in the leaves of A. kolomikta. Under stress conditions, the ratios of K/Ca and K/P declined to 0.9 and 6.3, respectively, whereas those of K/Cl, K/Mg, and K/Mo increased to 3.8, 4.4, and 2.7, respectively. The present studies confirmed that actinidia leaves contained high concentrations of minerals, especially K, Ca, P, and Mg, and that the accumulation of mineral elements in actinidia plant leaves under drought conditions varied depending on the species.

Five Rootstocks for “Emperor” Mandarin Under Subtropical Climate in Southern Brazil

Rootstocks modulate several characteristics of citrus trees, including vegetative growth, fruit yield and quality, and resistance or tolerance to pests, diseases, soil drought, and salinity, among other factors. There is a shortage of scion and rootstock cultivars among the combinations planted in Brazil. “Ponkan” mandarin and “Murcott” tangor grafted on “Rangpur” lime comprise the majority of the commercial mandarin orchards in Brazil. This low genetic diversity of citrus orchards can favor pest and disease outbreaks. This study aimed to evaluate the agronomic performance, Huanglongbing (HLB) tolerance, and fruit quality of “Emperor” mandarin on five different rootstocks for nine cropping seasons under the subtropical soil-climate conditions of the North region of the state of Paraná, Brazil. The experimental design was a randomized block, with six replications, two trees per block, and five rootstocks, including “Rangpur” lime, “Cleopatra,” and “Sunki” mandarins, “Swingle” citrumelo, and “Fepagro C-13” citrange. The evaluations included tree growth, yield performance, fruit quality, and HLB disease incidence. “Emperor” mandarin trees grafted on “Rangpur” lime and “Swingle” citrumelo had early fruiting and high yield efficiency. “Rangpur” lime also induced the lowest tree growth, but low fruit quality. Trees on “Swingle” citrumelo and “Fepagro C-13” citrange showed low scion and rootstock affinity and produced fruits with high total soluble solids (TSS), with a lower number of seeds for those from trees on “Fepagro C-13” citrange. “Cleopatra” and “Sunki” mandarins induced higher juice content, while fruits from trees on “Cleopatra” also had higher TSS/titratable acidity (TA) ratio. “Emperor” mandarin trees were susceptible to HLB regardless of the rootstocks. Overall, “Cleopatra” and “Sunki” mandarins, “Swingle” citrumelo, and “Fepagro C-13” are more suitable rootstocks for “Emperor” mandarin under Brazilian subtropical conditions than “Rangpur” lime.

Daily soil moisture mapping at 1 km resolution based on SMAP data for areas affected by desertification in Northern China

Land surface soil moisture (SM) plays a critical role in hydrological processes and terrestrial ecosystems in areas affected by desertification. Passive microwave remote sensing products such as the Soil Moisture Active Passive (SMAP) have been shown to monitor surface soil water well. However, the coarse spatial resolution and lack of full coverage of these products greatly limit their application in areas undergoing desertification. In order to overcome these limitations, a combination of multiple machine learning methods, including multiple linear regression (MLR), support vector regression (SVR), artificial neural networks (ANN), random forest (RF) and extreme gradient boosting (XGB), have been applied to downscale the 36 km SMAP SM products and produce higher spatial-resolution SM data based on related surface variables, such as vegetation index and surface temperature. Areas affected by desertification in Northern China, which are very sensitive to SM, were selected as the study area, and the downscaled SM with a resolution of 1 km on a daily scale from 2015 to 2020 was produced. The results show a good performance compared with in situ observed SM data, with an average unbiased root mean square error value of 0.049 m3/m3. In addition, their time series are also consistent with precipitation and perform better than some common gridded SM products. The data can be used to assess soil drought and provide a reference for reversing desertification in the study area. This dataset is freely available at https://doi.org/10.6084/M9.FIGSHARE.16430478.V5 (Rao et al., 2021).

Highly Productive Pine Forests in a Changing Climate

Forest steppe of the Central Chernozem Region (CCR) of Russia belongs to the zone of highly productive pine forests. In 2015, for the first time a partial destabilization of Scots pine (Pinus sylvestris L.) was recorded within the territory of the CCR. It affected the population, organism and cellular levels of Scots pine (Pinus sylvestris L.). The destabilization was caused by the 8-year heatwave of 2007–2014 followed by a sharp drop in the water table and four severe droughts (2007, 2010, 2012, and 2014). The analysis was carried out on two sites of pine forest plantations growing in the environmentally sound region: the Stupino test site (Voronezh region, typical plantation for the CCR) and the Usman site (Lipetsk region, lands with elevated groundwater level). The results of morphological, cytogenetic and biochemical studies of model trees of the Stupino test site during the following periods are presented: 4 optimal years in terms of weather conditions, 2014 drought year and 2015 destabilization year. It was found that prolonged hydrothermal stress resulted in the transition of pine from the basic equilibrium state to a slightly nonequilibrium state. The trigger mechanism for changing their vital state was a severe autumn soil drought in 2014, after which the plants became weakened right before winter. A decrease in cone bioproductivity by the traits of seed fullness and the total number of seeds per cone, a change in population sampling structure, an increase in the number of mitosis pathologies, and an increase in proline content in needles were observed despite optimal weather conditions in 2015. The recovery of species was studied for three subsequent optimal years on the example of the Stupino and Usman populations. Experimental data indicate that the processes of vital state normalization involve profound changes in metabolism and require certain energy expenditures. It took the Stupino population longer to return to the regional norm, which indicates a different depth of destabilization of the tree genetic material of the studied populations. For citation: Kuznetsova N.F., Klushevskaya E.S, Amineva E.Yu. Highly Productive Pine Forests in a Changing Climate. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 9–23. DOI: 10.37482/0536-1036-2021-6-9-23

Silicon Seed Priming Combined with Foliar Spray of Sulfur Regulates Photosynthetic and Antioxidant Systems to Confer Drought Tolerance in Maize (Zea mays L.)

The present study evaluated the effect of silicon (Si) seed priming and sulfur (S) foliar spray on drought tolerance of two contrasting maize hybrids viz. drought tolerant Hi-Corn 11 and susceptible P-1574. The maize seeds were primed with (3 mM Na2SiO3) or without Si (hydropriming) and later sown in pots filled with sandy loam soil. Drought stress (25–30% water holding capacity or WHC) was initiated at cob development stage (V5) for two weeks, whereas the well-watered plants were grown at 65–70% WHC. On appearance of drought symptoms, foliar spray of S was done using 0.5% and 1.0% (NH4)2SO4, whereas water spray was used as a control. The drought-stressed plants were grown for further two weeks at 25–30% WHC before the final harvest. The results showed a marked effect of Si seed priming and foliar S spray on biomass, physiological and enzymatic processes as well as macronutrient concentrations of maize. In comparison to control, the highest increase in leaf relative water content (25%), chlorophyll a content (56%), carotenoids (26%), photosynthetic rate (64%), stomatal conductance (56%) and intercellular CO2 concentration (48%) was observed by Si seed priming + S foliar spray (Si + S) under water deficit conditions. Also, Si + S application stimulated the activity of catalase (45%), guaiacol peroxidase (38%) and superoxide dismutase (55%), and improved NPK concentrations (40–63%) under water limitations. Our results suggest that Si seed priming + foliar spray of S is more effective than the individual application of these nutrients to enhance drought tolerance in maize.