RESPONSE OF SPATHIPHYLLUM WALLISII REGEL. AND PHILODENDRON SCANDENS C. KOCH AND H. SELLO PLANTS TO GAMMA IRRADIATION By MOHAMED ABD EL-SAMIAA SAYED KHALIFA B.Sc. Agric. Sci. (Ornamental Horticulture), Fac. Agric., Cairo Univ., 2010 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE In Agricultural Sciences (Ornamental Horticulture) Department of Ornamental Horticulture Faculty of Agriculture Cairo University EGYPT 2016 1 INTRODUCTION Peace lily (Spathiphyllum wallisii Regel) is a member of the family Araceae and one of the most popular indoor houseplants (Sardoei, 2014). It originates from Panama, Columbia, Ecuador, Venezuela, the Malay Archipelago, Costa Rica, and the Philippines where it thrives in humid, tropical rainforest understories. Peace Lily is an herbaceous evergreen with short, erect to creeping stems bearing tufts of foliage. Leaves are dark green and ovate to lanceolate. Wide selection of cultivars are ranging in height from 12 inches to 4 feet From an ornamental viewpoint, the spathes and spadices are called flowers rather than the tiny true flowers on the spadix. Inflorescences are produced seasonally or intermittently and can also be induced with chemical sprays. NASA even praised them in the clean air study for their ability to remove formaldehyde, benzene, and carbon monoxide from interior air (McConnell et al. ,2003). Interest in peace lily is steadily increasing as it is a shade tolerant indoor plant, dark green foliage and white spathes. The showy white spathes of Spathiphyllum enhance its popularity and marketing as a “flowering” foliage plant (Henny et al., 2004). Although it was initially a plant for container, in recent years, the culture of this plant has been greatly expanded for the production of cut flowers (Manda et al., 2014). Mature plants produce attractive white flowers that last several weeks. The natural flowering period for Spathiphyllum is generally Jan. through June. Natural flower production begins to decline over the summer and is at its lowest 2 level during the fall months (Henny, 1998). Environmental conditions and cultural practices for commercial production of Spathiphyllum have been established over the last 10 years. Conover (1992) recommended that plants should be produced under a photosynthetic photon flux density of 200 to 400 µmol m-2 s-1 and a temperature range of 20 to 32ºC. Philodendron is native to tropical regions of NorthSouth and Central America. The plant diversity is 250 species that comprise the genus. Although the genus name means “tree lover” in latin, many Philodendron species are herbaceous tree climbing vines, the genus also includes woody-stemmed plants that may reach 15 feet in height. In addition to great differences in leaf size, leaves of recently developed cultivars vary in color from dark red-black to light orange. (Chen et al., 2003). Heartleaf philodendron, Philodendron scandens, (Araceae family), is one of the most important ornamental foliage plants. It is an evergreen climber, with solid green leaves, a good houseplant and widely used for potted plants, totem poles, and hanging baskets. It thrives well in low light intensity, humid and temperate (Bailey and Bailey, 1976, Chen et al., 2005 and Gilman, 2011). Mature plants rarely flower; therefore, no reports of hybridization exist for this species (Henny et al., 2010). Cultural requirements for hear tleaf philodendron have been well documented previously (Conover and Poole, 1974). Heartleaf philodendron is normally propagated asexually by single eye cuttings. Vines do not develop secondary branches; growers 3 stick multiple eyes per container to obtain a full appearance in the final product. Genetic variation is necessary in any plant breeding program for crop improvement. Induced mutations are highly effective to enhance natural genetic resources and have successfully assisted in developing improved and new cultivars among both seed and vegetatively propagated crops. Mutations occur in cells in two ways. Firstly, by alteration in nuclear DNA which is also known as point mutation and it cause addition, deletion, transition and transversion in nucleolus of cell. Thus it changes the structure of nuclear DNA and mutations occurred. In second way, the mutagen makes the change in cytoplasmic DNA that is also called as cytoplasmic mutation. Gamma rays are used for improving growth and quality of plants, for their high mutation frequency that affect morphology, anatomy, biochemistry, and physiology of plants (Chahal and Gosal, 2002). Mutation breeding by gamma rays is one of the most powerful methods for developing new varieties, which is very successful in ornamental crops. Mohan Jain (2006) stated that induced mutations are highly effective to enhance natural genetic resources for vegetatively propagated crops. Several improvements in ornamental crops could be achieved by gamma mutation, including characters of flower and leaves, growth habit and physiological traits (Schum and Prell, 1998). Radiation mediated morphological, structural and functional changes in a plant are 4 governed by the intensity and duration of the gamma rays which generally induce cytological, biochemical, physiological, morphological and genetically changes in cells and tissues (Rahimi and Bahrani, 2011; Jan et al., 2012 ; Haris and Jusoff, 2013 and Chandrashekar et al., 2013 ). Ornamental plants are ideal for the application of mutations induction techniques because many economically important traits. Induced mutations in ornamentals comprise traits, such as altered flower characters (colour, size, morphology, fragrance); leaf characters (form, size, pigmentation); growth habit (compact, climbing, branching); and physiological traits such as changes in photoperiodic response, early flowering, free-flowering, flower keeping quality, and tolerance to biotic and abiotic stresses. They are easily monitored after the mutagenic treatment. Furthermore, many ornamental species are heterozygous and often propagated vegetatively; this allows the detection, selection and conservation of mutants in the M1 generation. Kurimato et al. (2010) found that the age at the time of radiation exposure plays an important role in integrating radiation effects. The gamma rays at high doses disturb the leaf gas exchange, hormone balance, water exchange and enzyme activities (Kiong et al, 2008). It has been suggested to use gamma rays at lower doses (1-10 Krad) to obtain useful mutants. The aim of this work was to study the effect of gamma irradiation treatments on growth, pigments, anatomical structure and DNA polymorphism, as well to induce genetic variations in 5 two important indoor house plants, viz., peace lily (Spathiphyllum wallisii Regel) and heartleaf philodendron (Philodendron scandens C. kock&H. Sello) plants and to apply RAPD analysis for genetic polymorphism among the different obtained variants. 6 MATERIALS AND METHODS This research was carried out in the greenhouse of the Ornamental Hort. Depart., Fac. Agric., Cairo Univ., Egypt, during the period from 2013 to 2015, to study the effect of gamma irradiation on growth, pigment contents and molecular aspects of Philodendron scandens and Spathiphyllum wallsii plants. 1- Effect of gamma irradiation on growth, pigment contents and leaf structure of (6-month-old) Spathiphyllum wallsii plants 2- Effect of gamma irradiation on growth and pigment contents of (3-month-old) Spathiphyllum wallsii plants Plant material The plants of the two ages were obtained from Egypt-Green Farm, Giza, Egypt. Gamma ray treatments: The plants of the two ages (6-month and 3-month old) were irradiated with 0, 0.5, 4 or 8 krad gamma rays, using a C137 source from a unit gamma chamber at a dose rate of 1 krad/13 sec. at the National Center for Radiation Res. and Tech., Nasr City, Cairo, Egypt. The experiment: On 17 July, 2013, the irradiated plants of the two ages were planted individually in plastic pots (20cm-diameter) 7 using a mixture of sand + peat+ perlite (1/2/1, v/v) and set under a high-humidity propagation unit (plastic tunnel) with intermittent mist for a month. After a month, on 16 August, the plants were moved to raised benches in the greenhouse. NPK fertilizer (Krestalon, 19-19-19) was applied (monthly) to pots at 1.5 g/pot. Irrigation was done as the plants needed. Data recorded Data were recorded at two dates for the two ages as follows: a. After 6 months of growth on the following characters: 1. Survival %. 2. Plant height. 3. Stem diameter. 4. Number of leaves/plant. 5. Leaf area. 6. Petiol length. b. After 12 months of growth on the following characters: 1. Survival %. 2. Plant height. 3. Stem diameter. 4. Number of leaves / plant. 5. Leaf area. 6. Petiol length. 7. Fresh weights of plant, leaves and stems. 8 8. Leaves/stem ratios (fresh weight). 9. Pigment content. 10. Leaf anatomical structure. The second Experiment: Effect of gamma irradiation on growth, physiological and molecular aspects of Philodendron scandens plant Plant material Mother plants (stock) of Philodendron scandens (in 30cm plastic pots) were obtained from Egypt-Green Farm, Giza, Egypt. The stock plants were located in a greenhouse. On 17 July, 2013, stem cuttings (10-12 cm height) were obtained from the mother plants. Gamma ray treatments Stem cuttings were irradiated with 0, 0.5,2, 4 or 8 krad gamma rays, using a Co60 source from a unit gamma chamber at a dose rate of 1 krad/13 sec. at the National Center for Radiation Res. and Tech., Nasr City, Cairo, Egypt. The experiment The irradiated cuttings were stuck in trays, using a mixture of sand + peat (1/2, v/v) and forced to root under a high-humidity propagation unit (plastic tunnel) with intermittent mist. After a month, on August, the rooted cuttings were individually transplanted into 20-cm plastic pots, using a mixture of sand+ peatmoss+ perlite (1/2/, v/v) and set on raised benches in the greenhouse. NPK fertilizer (Krestalon, 19-19-19) was surface applied (monthly) to pots at 1.5 g/pot. 9 Statistical analysis A randomized complete block design with 3 replications was used. Each treatment consisted of ninty of treated plants.