Volume 35, No. 1 (2026)

COMPARATIVE STUDY ON TOMATO VARIETIES SELECTION IN THE PROTECTED CONDITIONS OF JORDAN VALLEY FOR YIELD AND PEST RESISTANCE

This study is significant for its applicability in screening tomato varieties under the protected cultures of the Jordan Valley with pest management practices. The experiment aimed to compare the performance of three tomato varieties (Dafnis, SV4129, and Newton) grown in the protected cultures of the Jordan Valley in terms of yield, and resistance to fungal diseases and viral infections. The varieties selected are among the most preferred varieties in the Jordanian market and are widely adopted by local growers. The research evaluated yield and key quality traits, including plant vigor, internode length, flowering, and fruit set, as well as important plant and fruit characteristics for each variety. The varieties were cultivated under greenhouse conditions in the Jordan Valley over one growing season, from 1 October 2023 to the end of March, with a growth period of approximately 150 days. The highest yield was obtained from the Newton cultivar. The results indicated that Dafnis and SV4129 exhibited strong resistance to Pythium, Fusarium, and the viral diseases Tomato Yellow Leaf Curl Virus (TYLCV) and Tobacco Mosaic Virus (TMV). Based on these findings, Newton is recommended for cultivation under protected conditions in the Jordan Valley, where effective virus management is in practice. However, in production systems with inadequate virus control, the adoption of the Newton cultivar is not advised due to its higher susceptibility to viral infections.

VARIATION IN THE ACTIVITY OF PEROXIDASE AND CATALASE ENZYMES IN PLUM TREES LEAVES, DEPENDING ON GROWING CONDITIONS AND BIOLOGICAL PARTICULARITIES OF THE VARIETY

Our study examines the enzymatic antioxidant defense of plum plants, through the assessment of the activity of the enzymes peroxidase and catalase in the leaves of different plum tree varieties cultivated under irrigated and non-irrigated conditions during the growing season. The importance of these enzymes lies in their participation, with differentiated roles, in the adaptation and resistance of trees to unfavorable environmental conditions, as well as in the processes of growth, development and fruiting. The results of the investigations revealed an intensification of peroxidase activity in the leaves of trees grown under non-irrigated conditions. Compared to irrigated trees, the values were higher by 24.20 % in the Stanley variety, by 32 % in the Udlinionnaia, by 23.53 % in the President and by 3.17 % in the Super Prezident. During the vegetation period, the highest activity of the catalase enzyme in the leaves was observed in trees grown under non-irrigated conditions. Compared to trees grown under optimal humidity conditions (with irrigation), the enzyme activity was higher by 16.59 % in the Stanley variety, by 19.74 % in the Udlinionnaia variety, by 10.58% in the President variety and by 10.10 % in the Super Prezident variety. The research contributes to the completion of knowledge about the mechanisms of plant tolerance to stress. Understanding these mechanisms could serve as a basis for improving antioxidant defense systems, by further developing procedures for targeted management of the functional state and optimization of the production process in fruit trees in the context of climate change, such as the application of various biologically active substances. The dynamics of the activity of the studied enzymes varied during vegetation, being influenced by the developmental stages of the trees, environmental factors, growth conditions and genotype.

A DECADE OF PHYTOPLASMA RESEARCH: STOLBUR IDENTIFICATION IN MOLDOVAN TOMATO VARIETIES

Tomato crop in Moldova is threatened by ˈCandidatus Phytoplasma solaniˈ, a phloem-limited pathogen transmitted by insect vectors. Local tomato varieties were screened by nested-PCR during ten years (2016–2024). Results showed clear variety-dependent susceptibility. Variety Cerasus displayed stable partial resistance (<35% of infected plants). Elvira and Desteptarea were highly vulnerable (50–85%) while Mary Gratefully showed variable incidence (33–92%) influenced by climate conditions of the year. The summarized infection data fluctuated widely between years from epidemic levels (83% in 2016, 72% in 2023) to minimal incidence (10% in 2020). Sequencing of isolates confirmed the persistence of identical strains of phytoplasma over the growing seasons (2018–2020). Ten-year study provides a comprehensive overview of epidemiological situation of ˈCa. P. solaniˈ in the Republic of Moldova and offers valuable information for tomato breeders as well serving a basis for disease control strategies.

PHOTOSYNTHESIS AND WATER STRESS: MOLECULAR MECHANISMS, PHOTOCHEMICAL REGULATION, AND INTEGRATIVE STRATEGIES OF PLANT DROUGHT TOLERANCE – A REVIEW

In this review, water deficit remains one of the major constraints on plant productivity under rising temperatures, increasing atmospheric aridity, and the growing frequency of extreme weather events. Photosynthesis responds to drought not simply as a consequence of reduced water availability, but as a systemic disturbance of hydraulic, carbon, energy, and redox balance. At the early stage of stress, the decline in net CO2 assimilation is determined mainly by stomatal closure and reduced stomatal conductance; however, as water deficit intensifies, the roles of mesophyll conductance, biochemical capacity for CO2 assimilation, ribulose-1,5-bisphosphate regeneration, and thylakoid membrane function become increasingly important. In parallel, reduced chloroplastic CO2 availability enhances photoprotective processes, alters ATP/NADPH balance, and increases the importance of photorespiration, mitochondrial respiration, and antioxidant defense. This review synthesizes current concepts of ABA -dependent and ABA - independent stomatal closure signaling, non -stomatal limitations of photosynthesis, photochemical regulation, and the roles of photorespiration and redox homeostasis, with particular emphasis on the diagnostic value of integrating gas exchange with PAM - fluorometry. Drought tolerance is interpreted as a multicomponent trait emerging from the coordination of molecular, physiological, morphological, and recovery related processes across levels of plant organization.

WESTERN FLOWER THRIPS POPULATION DYNAMIC ON GREENHOUSE SWEET PEPPER

Western flower thrips (Frankliniella occidentalis, WFT) is an important pest of sweet pepper in greenhouses in the Republic of Moldova. A greenhouse population of WFT on sweet peppers, which is difficult to control, has been studied. The high growth rate of the WFT population (333%) and its dominant position (56%) are largely dependent on ecological factors in greenhouses and the insecticides used. There is no interspecific competition between local thrips species and the invasive WFT due to the low abundance and species diversity of thrips. The prolonged and frequent use of insecticides without alternative control measures has resulted in 51.7±2.6%, 20.6±1.8% and 22.0±3.3% adults of the population being resistant to the active ingredients of the insecticides cypermethrin, thiamethoxam and abamectin, respectively. No resistance to spirotetramat has been detected in WFT larvae. The year-round cultivation of vegetable and ornamental crops in Ecoplantera's greenhouses contributes to the preservation of this pest population. To ensure sustainable control of WFT in greenhouses, it is recommended to apply an integrated pest management (IPM) approach, with the obligatory use of entomophages and entomopathogens.