The Effects of X Rays and Thermal Neutrons on the Development of Trailing Indigo (Indigofera Endecaphylla) Plants

Abstract

DIFFERENT DEVELOPMENT PATTERNS, mostly variations in size, were observed among young plants of trailing indigo (Indigofera endecaphylla Jacq.) arising from seed which had been subjected to various dosages of X rays and thermal neutrons in an attempt to induce beneficial, particularly agronomic, mutations. This study of radiation effects resulted from these observations and the desirability of analyzing the differential growth responses apparently induced by X radiation and thermal neutron flux in dormant seeds of trailing indigo.The existence of a greater quantitative factor, or relative biological efficiency (RBE), for thermal neutrons as compared with X rays is generally recognized. On the basis of equivalent total ionizations, thermal neutrons have about 11 or 12 times the effectivity of X radiation in causing cytogenetic change (Conger and Giles, 1950). In addition to the greater RBE for thermal neutrons as compared with X rays, qualitative differences, different biological effects, have been observed by some workers (Caldecott et al., 1952(Caldecott et al., , 1954 Spencer and Blakeslee, 1%5), and denied by others (Snider, 1948; Frolik and Morris, 1950;Schmidt, 1952). Of primary concern in comparative studies of mutagenic agents is whether or not the biological effects of these agents differ in any fundamental way. The initial purpose of this investigation was to study the nature of the different effects noted in trailing indigo plants arising from seed exposed to X radiation and to thermal neutrons. A second purpose was to find if any apparent difference is related to growth substance activity and/or to protein metabolism.MATERIALS AND METHoDs.-In order to obtain comparative data concerning the responses of trailing indigo plants to dosages of X rays and thermal neutrons, a series of experiments was designed to analyze effects on germination, survival, development, relative growth substance activity, protein metabolism, and pollen production. Seeds of trailing indigo produced at this station were dried to a moisture content of four per cent (-+-0.5 per cent), and used throughout these tests. The self-fertility of this legume assured a high degree of homozygosity (manifest by the uniformity of juvenile and adult characters). Separate lots were treated as follows: 0, and thermal neutrons (total dose) : 0, 7.91 X 10 1 2 , 1.47 X 10 13 , 2.80 X lOIS, 3.43 X 10 13 , 2.11 X 101 3 , 5.04 X 10 1 3 , 6.15 X 10 1 3 , 7.73 X 10 1 3 , 9.84 X 10 1 3 , and 1.30 X 10 Hn/cm. 2 (neutrons per square centimeter). Immediately upon their return, these seeds, together with those retained as additional controls, were scarified with concentrated sulfuric acid for 30 min., washed thoroughly in distilled water, dried, and germinated in Petri dishes or planted in clay pans. Germination percentages were obtained at four days, one week, and two weeks from seeds placed on moist filter paper in Petri dishes and maintained at room temperature (24 0-29 0 C.). Six replicates of 100 seeds to a dish constituted each sample. Data on survival,...

Effects ofin Planta gamma-irradiation on growth, photosynthesis, and antioxidative capacity of red pepper (Capsicum annuum L.) plants

“…Although these phenomena of 'radiation hormesis' have long been analyzed (Luckey, 1980;Sagan, 1987;Calabrese, 2002), this concept has also been challenged by the small magnitude and transience of the reported hormetic effects of radiation (Spencer and *Corresponding author; e-mail bychung@kaeri.re.kr Cabanillas, 1956;Marchi et al, 1962;Miller, 1987) and by frequent failures to reproduce those effects (Skok and Charney, 1962;Miller 1987;Zaka et al, 2004). In many cases, this may be due to differences in plant species/cultivars, developmental stages, or growing conditions (Kim et al, 2004a, b).…”

Effect of Gamma Rays on Growth and Karyokinetic Activity in <i>Trigonella foenum-graecum</i> L

“…Jones and Plummer in 1960 re ported stimulating effect on Trifolium. An early stimulating effect on growth of Indigofera as a result of X-rays was reported by Spencer and Cabanillas (1956 Sorghum no growth stimulus was observed by Kankis and Webster (1956). Studies of Osborne and Bacon (1960) on different species showed no stimulation of seedling growth following seed irradiation at 5-100,000 r except in one of the eighteen test.…”

Influence of Seed Irradiation with X-Rays and Thermal Neutrons Upon Cell Size and Mitotic Activity in Root Tips of Maize

“…In recent years a number of reports (for example, Caldecott e t al., 1952Caldecott e t al., , 1954Caldecott e t al., , 1955Schmidt and Frolik, 1951;Schwartz, 1954;Schwartz and Bay, 1956;Spencer and Cabanillas, 1956;Yagyu and Morris, 1957) have appeared which deal with the effects of treating seeds with various high energy radiations. In all c a s e s it i s reported that seedlings grown from appropriatelyirradiated seeds are reduced in stature.…”