Generative and reproductive qualities in taxa of the genus Gleditsia in arid conditions

Abstract

Representatives of the genus Gleditsia are valuable trees for landscaping settlements. In areas with saline soils (southeast of the European part), they are distinguished by a high degree of drought resistance and tolerant to the conditions of solonetzic soils. Show decorativeness in alleys, single plantings and small groups. The main source material for their reproduction is seeds. The question of studying the ecology of flowering is of great importance for the determination of seed setting. The purpose of this work is a comparative analysis of the quality indicators of seeds of the following species of introduced species of different geographic origin growing in chestnut soils: common gleditsia (Gleditsia triacanthos), common gleditsia thornless (Gleditsia triacanthos, f. Inermis), Caspian gleditsia (Gleditsia caspica) texas (Gleditsia texana). They grow in the dendrological collections of the Federal Research Center of Agroecology of the Russian Academy of Sciences cadastre 34: 34: 000000: 122; 34: 34: 060061: 10, Volgograd region. The study area is characterized by dry, hot summers, lack of precipitation, and temperature ranges up to 80 ° C. The temperature of the coldest month reaches -37 ° С, and in summer the air warmed up only to zero. The absolute maximum is + 42 ° C in summer. The average annual precipitation is 240–400 mm. Drought is a common occurrence for the arid region. High and medium intensity of recurrence of droughts reaches 50%. Natural and climatic conditions of the region are not favorable for landscaping and afforestation. Dry winds carrying streams of hot air have a detrimental effect on plants. In summer, dust storms occur that damage green spaces and soil fertility. Therefore, in arid conditions, a careful approach to the selection of tree species is required. The duration of flowering of Gleditsia has been established, which depends on the geographical area of ​​origin. Representatives of the northern range (G. triacanthos and G. texana) bloom earlier than all, and later, the southern one (Gleditsia caspica). Morphometric analysis was carried out (seed color, weight, length, width of seeds). The percentage of germinated healthy and pest-infested (Megabruchidius dorsalis) seeds was revealed; germination in relation to seed characteristics. The indices of good quality of seeds in Gleditsia triacanthos under the conditions of chestnut soils of the Volgograd region are at a rather high level (76.82%) compared to the indices of seeds in Gleditsia texana, where the indices of goodness are within 46.81%. It was revealed that during the period of seed maturation in various species of the genus Gleditsia, changes in their size and color were observed. The seeds of Gleditsia triacanthos are elongated, elliptical, flattened, brown, and firm. The color of the seed coat changed in spotty transitions from dark green to dark cinnamon. The size decreased by one unit every day, until it reached 10 mm in length and 5 mm in width, which is 1.5 times more than in Gleditsia triacanthos, f.inermis. Gleditsia caspica has oval seeds 10 mm long and 6 mm wide, while G. texana has a rounded seed shape of 9-10 mm in length and 7-8 mm in width in plants growing in arid conditions of chestnut soils. Gleditsia seeds remain viable for a long time due to their hard shell, so they can be included in the exchange fund with guaranteed shelf life from 1 to 7 years. Germination of Gleditsia seeds depends on the conditions of their natural habitat. Seeds of G. triacanthos are distinguished by good germination. In dry years (due to high temperature and water shortage), damage by pests and diseases was revealed in the seeds of G. caspica. Seeds of North American species of the genus Gleditsia germinate dynamically. Warmer and drier conditions are beneficial for the development of Gleditsia seeds.