التحفيز الحيوي بالكايتوسان العادي والنانوي في بعض صفات النمو لشتلات التيكوماTecoma stans (L.) Juss. Ex Kunth. تحت مستويات مختلفة من الإجهاد المائي

Biostimulation of normal and nano-chitosan on some growth characteristics of Tecoma seedlings Tecoma stans (L.) Juss. Ex Kunth. under different

Abstract:
The study was conducted in the canopy covered with green saran with a shading rate of (50%) of the natural light intensity of the nursery of the Holy Shrine of Al-Hussainiya in Al-Hafiz area of Al-Hussainiya district for the period from the beginning of February to the month of October of 2022 to study the effect of normal and nano-chitosan on the seedlings of the Tecoma shrub Tecoma stans (L.) Juss. ex Kunth. at the age of (10 months) under the influence of different levels of water stress, where the first factor included the use of three levels of water stress by (50, 75 and 100%) of the field capacity value and the second factor was normal chitosan with three concentrations (0, 150 and 300 mg. L-1), and the third factor was nano-chitosan with three concentrations (0, 150 and 300 mg. L-1), thus, the experiment becomes factorial with three factors (3 x 3 x 3) and (27) factorial treatment. A complete randomized block design with three sectors was used, and thus the number of experimental units in the study is 81 experimental units, and each experimental unit consists of Five observations. The process of statistical data analysis was conducted for all the studied traits according to the design of the experiment using the SAS program for statistical analysis (2012). The averages of the treatments were compared statistically according to Dunkin’s multiple range test.
The results of the single effect of water stress showed that the seedlings that were treated with a light water stress treatment by (100%) of the field capacity value were significantly superior in most of the studied vegetative, root and chemical growth characteristics, including the increase in the height of the seedlings, the number of leaves, the length, diameter and size of the root, the characteristic of the dry weight of the root system and the content relative moisture content of leaves, content of leaves of carbohydrates and total proteins, content of leaves of total chlorophyll, a and b, in addition to its content of nitrogen, phosphorus and potassium, and the activity of the catalase enzyme, while the lowest accumulation of proline was recorded in the seedlings that were treated with light water stress by (100%) of the value of the field capacity. The results of the single effect of the normal and nano-chitosan biostimulant showed the superiority of the seedlings that were treated with the concentration (300 mg. L-1) in most of the studied traits except for the stability of cell membranes compared to the control treatment whose seedlings recorded the lowest significant rate in all the studied traits.
The results of the bilateral interactions between water stress at a rate of (100%) of the field capacity value and normal chitosan concentration (300 mg. L-1) showed significant superiority in most of the vegetative and root growth traits as well as the chemical traits, including the characteristic of increasing the height of seedlings at a rate of (67.77 cm), and the increase in the diameter of the stem at a rate of (2.455 mm), and the increase in the number of leaves at a rate of (19.11 leaves), as well as the increase in the number of branches at a rate of (2.77 branches), the length of the main root at a rate of (65.88 cm), and the diameter of the main root at a rate of (9.27 mm). ) and root volume at a rate of (67.333 cm3), dry weight of the root system at a rate of (14.666 g), relative moisture content at a rate of (84.47%), in addition to carbohydrates at a rate of (2.756 mg.g-1) and total proteins at a rate of (15.21%) as well as The leaf content characteristic of total chlorophyll, a and b, with a rate of (1.782, 1.289, and 0.493 mg.g-1 fresh weight), respectively, and the average leaf content of nitrogen, phosphorus, and potassium, respectively (2.435, 0.34, and 1.306%), and an activity rate the catalase enzyme reached (9.956 units.g-1.min), and the leaf content of the amino acid Proline was (6.30%).
The results of the statistical analysis of the binary interaction coefficients between water stress at a rate of (100%) of the field capacity value and nano-chitosan concentration (300 mg.L-1) showed a significant superiority in most of the vegetative and root characteristics, including the characteristic of an increase in the height of seedlings at a rate of (65.22 cm) and a characteristic of the increase in the number of leaves at a rate of (16.22 leaves) and the root volume at a rate of (65.333 cm3) and the characteristic of relative moisture content at a rate of (84.23%), the results also showed a significant superiority in the content of Tecoma leaves of carbohydrates, at a rate of (2.797 mg.g-1), and total proteins, at a rate of (14.55%), as well as the leaf content of total chlorophyll, a, and b, at a rate of (1.836, 1.327, and 0.508 mg. g-1), respectively, and the mean content of the leaves of nitrogen, phosphorus and potassium, respectively, was (2.330, 0.32, and 1.259%). The treatment of the binary interaction between normal and nano-chitosan had a significant effect on all the studied vegetative and root traits as well as the chemical characteristics, especially at the concentration (300 mg. L-1) for each of the two compounds together compared to the control treatment, while the seedlings that were treated with normal chitosan excelled at a concentration (150 mg. L-1) and nano-chitosan concentration (300 mg. L-1) in the potassium content of the leaves of Tecoma seedlings with an increase rate of (9.12%) compared to the control treatment that gave a lower content.
The triple interaction treatment between the study factors achieved significant differences in most of the studied traits, as the water stress treatment (100%) of the field capacity value with normal and nano-chitosan concentration (300 mg. L-1) recorded the highest significant rate of increase in seedling height and number of leaves, and the length of the main root and the content of the leaves of carbohydrates, total proteins, total chlorophyll and chlorophyll a, and the content of the leaves of the element nitrogen, phosphorus and potassium, while the treatment of the triple overlap between water stress by (100%) of the field capacity value with normal chitosan concentration (300 mg. L-1) and nano-chitosan concentration (0 mg. L-1) had a significant effect on the increase in stem diameter and leaf content of the amino acid Proline.