In arid conditions where many plants struggle to survive, Robinia and Gleditsia demonstrate remarkable resilience, revealing the secrets of reproductive success in extreme environments.
The steppe regions of the Volgograd Oblast with their light chestnut soils and arid climate represent a challenging environment for woody plant growth. Under these conditions, plant reproductive capacity determines their potential use in protective afforestation and greening of settlements.
In the context of this research, includes a complex of characteristics: from flowering and fruit set to seed germination and seedling development.
A scientific direction dealing with the study and improvement of generative plant qualities, taking into account their adaptation to specific growing conditions.
Robinia and Gleditsia belong to economically important and promising species for degraded landscapes of arid regions. Their study aims to identify and expand prospective cultivation areas for forest reclamation and greening of settlements 1 .
Studies were conducted in 2017-2019 on collection sites of the Federal Scientific Center for Agroecology of the Russian Academy of Sciences. The objects of study were various species and forms of the genus Robinia: R. viscosa Vent., R. neo-mexicana Gray., R. pseudoacacia L., R. neo-mexicana х pseudoacacia, and Gleditsia: G. triacanthos L., G. triacanthos L. f. inermis, G. caspica Desf, G. texana Sarg., G. aquatica, G. japonica, G. caspica, G. sinensis 1 .
2017-2019
Federal Scientific Center
7+ species each genus
The development of the foundations of selection seed science was based on the study of reproductive features of identified bioresources for targeted use, taking into account the possibilities of comprehensive study of generative qualities and assessment of biological potential.
The research revealed several key factors affecting the reproductive capacity of plants in dry-steppe conditions:
Stable fruiting is recorded several years after the start of flowering - for Robinia and Gleditsia this period is 6-7 years 1 .
First flowering in Gleditsia triacanthos and G. texana was observed at 5 years, G. japonica at 6 years, G. caspica and G. sinensis at 8 years 1 .
Fruit set depends not only on plant age but also on weather conditions during flowering 1 .
Seed productivity is influenced by the amount of precipitation and the sum of active temperatures during fruit ripening 1 .
A separate study was devoted to the stages of seedling formation of various species of the genus Gleditsia in dry-steppe conditions. Researchers considered the time intervals of seedling development and determined the features of seedling formation .
For growing Gleditsia seedlings, researchers used loamy soil with a plow layer depth of about 30 cm. Seeds were pre-treated with hot water at 80°C. This method helped overcome seed dormancy and stimulate germination .
Not all seedlings successfully completed the full development cycle. Some seedlings of G. triacanthos (36.46%) could not fully complete development stages due to external factors (temperature, humidity). The largest number of underdeveloped seedlings was in G. caspica (77.78%), which is explained by its natural habitat .
| Plant Species | First Flowering Age | Seedling Development Speed | Ontogenesis Completion Success |
|---|---|---|---|
| Gleditsia triacanthos | 5 years | Fast | 63.54% |
| Gleditsia texana | 5 years | Very fast | Data not provided |
| Gleditsia japonica | 6 years | Data not provided | Data not provided |
| Gleditsia caspica | 8 years | Medium (early formation) | 22.22% |
| Gleditsia sinensis | 8 years | Data not provided | Data not provided |
Table 1: Comparative characteristics of reproductive features of various Gleditsia species 1
Research showed that Gleditsia caspica seedlings prefer more moist soils (70%). However, at high humidity (85%), microbiota develops in the soil, which hinders root system development. Good growth was observed in seedlings growing in dry conditions with loose soil .
| Parameter | Value | Conditions |
|---|---|---|
| Seedling yield per hectare | 600-700 thousand pieces | With agricultural technology compliance |
| Irrigation rate | 150-200 m³ per hectare | One irrigation sufficient for normal growth conditions |
| Optimal soil moisture for G. caspica | 70% | Exceeding leads to pathogenic microbiota development |
Table 2: Seedling yield and irrigation conditions for Gleditsia triacanthos in dry-steppe conditions
In the context of plant reproductive features, the experiments of Georgy Shaposhnikov on artificial evolution, conducted in the late 1950s - early 1960s, are of interest. In these experiments, host plants were changed for various aphid species, leading to reproductive isolation of the experimental individuals from the original population 3 .
Shaposhnikov's research showed that the average mortality of aphid larvae on the primary host plant was low. However, during the period of adaptation to a new host plant, mortality increased tens of times and in some cases reached 100%. After the adaptation period, mortality decreased to levels characteristic of species initially specialized on that plant 3 .
Similar processes are observed in plants during their adaptation to new ecological conditions, as confirmed by studies of the reproductive capacity of Robinia and Gleditsia in the dry-steppe zone.
Based on the conducted research, optimal conditions for successful seed propagation of the studied species in dry-steppe conditions were determined:
Optimal soil temperature for seed germination is 20-24°C .
Maintain optimal moisture, avoiding both drying out and waterlogging .
For growing Gleditsia seedlings, loamy soil with plow layer depth about 30 cm is preferable .
Seeds require preliminary treatment with hot water (80°C) to overcome dormancy .
Regular assessment of development stages and environmental factor impacts 1 .
Temperature
20-24°C
Moisture
70% (G. caspica)
Treatment
Hot water (80°C)
Soil Depth
30 cm loamy
Studies of the reproductive capacity of representatives of the generic complexes Robinia and Gleditsia in dry-steppe conditions allow not only to expand scientific understanding of plant adaptation capabilities but also to solve practical problems of protective afforestation and greening of settlements in arid regions.
The identified features of selection seed science of these economically important species open prospects for targeted selection of the most resistant and productive forms for specific soil and climatic conditions.
Recent research in this area confirms that plants have an amazing ability to adapt, and studying their reproductive strategies in extreme conditions opens new opportunities for green development of arid territories.