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العنوان
Effect of Gamma and Laser Rays on Growth and Flowering of Salvia coccinea Plants and Their Physiological Response to Drought Stress /
المؤلف
Mostafa ؛ Mohamed Sayed Gad ز
هيئة الاعداد
باحث / محمد سيد جاد مصطفي
مشرف / اسماعيل حسن السلامي
مناقش / أحمد فؤاد علي
مناقش / أحمد شاكر حسين
الموضوع
Floriculture .
عدد الصفحات
281p .
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
البساتين
الناشر
تاريخ الإجازة
31/10/2019
مكان الإجازة
جامعة أسيوط - كلية الزراعة - Horticulture
الفهرس
Only 14 pages are availabe for public view

from 302

from 302

Abstract

The present work was carried out at the Nursery of ornamental plants, Faculty of Agriculture, South Valley University during successive seasons of 2016/2017 (M1 generation) and 2017/2018 (M2 generation) to define the most effective combination of gamma or laser-irradiated seeds of Salvia coccinea and moisture supply in enhancing the tolerance to drought stress that developed in M1 and M2 generations.
Seeds were irradiated in October 2016 with gamma-rays at 5, 10, 15, 20 and 25 K.rad or laser-radiation for 5, 10, 15 and 20 min. exposure time, in addition unirradiated control and then immediately planted in pots filled with clay soil. After complete emergence of the irradiated seedlings (40-day-old) transplanted singly into pots of 2.2 l contained 3.5 kg air-dried clay soil to follow up the growth and development of the newly generated plant under different soil moisture levels; 100 (control), 80, 60 and 40% F.C in M1. Because of the failure of high water stress (40% F.C) in seed set at the end M1, M2 plants were irrigated at three moisture levels (100, 80 and 60% F.C).
Pots were placed in polyhouse clear sheets under partial shade conditions (50% shade), ambient temperature 20-35°C and relative humidity 70-75% until the end of M1 and M2 (June 2017 and 2018). Pots were arranged in split-plot design; the main plots were soil moisture levels and sub-plots were pre-sowing irradiation. Each experimental unit contained four plants (pots) and replicated three times. Data were recorded on germination attributes, the parameters of vegetative growth, root system and flowering, as well as leaf contents of some macro and micro-nutrients and their uptake by plant, some active biochemical constituents, enzymatic activities and physiological traits.
The following results obtained:
- Gamma irradiation showed strongly stimulative effect on germination attributes (germination percentage, mean daily germination and germination velocity) compared to laser-rays. The response of seeds to gamma-radiation was depended on the dose used since 25 and 15 K.rad resulted in the highest increasing in most measurements in M1 and M2 generations.
- At high water stress (40% F.C) plants showed great reductions in growth and flowering, however, at 60% F.C significantly decreased all vegetative growth, root system and flowering parameters compared to the higher moisture levels at 80 and 100% F.C which achieved the best results showing insignificant difference between them in most cases.
- Gamma doses were more effective in their efficiencies on growth and flowering than laser-radiation. In general, the highest increased characteristics studied were occurred at 15-25 K.rad. Among laser rates, the exposure for 10 min. gave higher growth and flowering than other rates, meanwhile, the exposure for 20 min. recorded the worst results.
- A direct relationship between the concentration of nutrient elements in the soil solution, their uptake by plant and leaf content was found except total K uptake which resulted in opposite trend to that of leaf K at different soil moisture levels.
- Increasing the soil moisture level significantly increased leaf contents of P, Ca and Mn, but it significantly decreased N, K, Mg, Fe and Zn.
- Gamma radiation was more pronounced in total nutrients uptake by plant than laser. Gamma at 5 K.rad showed the highest leaf content and uptake of N, P, Ca and Mn, while 20 K.rad resulted in the highest K, Mg, Fe and Zn. Leaser exposure for 20 min. significantly decreased leaf content and total uptake of all tested nutrient elements compared to control.
- The obtained results from chemical analysis appeared many negative interactions (antagonistic) among macro and micro-nutrients whereas the concentration of one nutrient decreased and the other increased at the different moisture levels such as (N&P), (P&Fe), (P&Zn), (Ca&K), (Ca&Mg), (Fe&Mn) and (Mn&Zn).
- Plants of M2 generation revealed marginal differences in leaf contents and some increments in total nutrient uptake ranged 13-15% compared to their parents of M1. Meanwhile, Mn behaviour is in direct contrast to this as reduced total Mn uptake by 7-11% in M2.
- The optimum growth and flowering were closely associated with the increased blanced total uptake of nutrients and their concentrations in leaves in most cases, as well as increase in photosynthetic pigments, total carbohydrates and protein in leaves and endogenous promoted hormones (IAA and GA) in plant. Accordingly, the worst growth was correlated with the lowest constituents.
- A direct relationship between the great reductions in growth and flowering resulted from drought stress and the decreased leaf relative water content also the increasing in the contents of total phenolic compounds, proline and abscisic acid in plants was found.
- There were significant changes in the activities of the defensive enzymatic systems in plant under drought stress conditions. Apparently, the activities of peroxidase and catalase in leaves of irradiated plants with gamma or laser were higher at 60% F.C than in other moisture supply.
- It was observed that the physiological changes and active biochemical constituents obtained by gamma or laser-rays in M1 were continued to M2 with higher concentrations in most cases.
- Decreasing soil moisture levels reduced pollen viability percent. Gamma-radiation was more stimulative than laser-rays in this respect. Gamma at 15 and 20 K.rad with water supply at 80% F.C recorded the highest pollen viability.
- Soil moisture levels at 80 and 100% F.C decreased stomata number of leaf, but they increased stomata length. More tolerance to drought is less stomata density in leaf under control condition. Otherwise, the behaviour of soil moisture at 40 and 60% showed adverse effects whereas they increased stomata number and decreased stomata length. Since stomata diameter was not affected by soil moisture content.
- Stomata number was not affected by gamma and laser-rays, but they increased stomata length. Stomata diameter was increased by gamma irradiation at 5-15 K.rad.
- In general, the obtained results appeared that initiated resistance of Salvia coccinea plants under drought stress are enhanced after pre-sowing seed irradiation with gamma at 15-25 K.rad followed by laser for 10 min. exposure time.
- The interaction effects between irradiation treatments and soil moisture content indicted that the best combinations were obtained from gamma-rays (15-25 K.rad) with moisture supply at 80% F.C. These combinations were closely correlated with considerable improvement in growth and flowering characters, led to protect the plants from the deleterious effects of drought and consume 30% of irrigation water. It could be recommend to use it.
- Some morphological variations were appeared in M2 for S. coccinea plants as mutations induced by the irradiation with various doses of gamma and laser including form, size and growth habit of leaves, branches and inflorescences.
- The inter simple sequence repeats (ISSR) markers were used to evaluate the mutagenic effect of different treatments of gamma and laser on DNA sequence, to evaluate the DNA alteration level if any compared to control and to confirm the morphological variation findings. Significant correlations between the nuclear DNA concentration in leaves and the morphological variations were found. This indicated that gamma or laser-rays at lower rates lead to less radiation damage in plants during mutant induction.