page 124 Impact of gamma rays on turmeric crop (Curcuma longa L.) H. Usha Nandhini Devi and N. Chezhiyan Department of Vegetable Crops Horticultural College & Research Institute Tamil Nadu Agricultural University, Coimbatore - 641 003, India E-mail : drushajana@rediffmail.com ABSTRACT Experiments were carried out during 2000-2003 at the Department of Spices and Plantation Crops, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, to assess the impact of gamma irradiation on days to maturity, yield and curing per cent in turmeric (Curcuma longa L.). The experiment was laid out in Factorial Randomized Block Design with two replications. Three genotypes namely, Salem Local - G 1 (CL144), Alleppy finger turmeric - G 2 (CL146) and PTS 43 - G 3 (CL147) were treated with seven doses of gamma rays (1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 kR) along with control. The plants matured earlier and yield per plant and curing percentage improved at 2.0 kR, followed by 2.5 kR, whereas, higher doses of gamma rays had a negative effect on yield and curing percentage and these higher doses prolonged maturity. Among the genotypes used, G 1 (CL144) was found to show a good response to gamma irradiation. Key words : Gamma rays, turmeric crop, irradiation, yield, curing percentage INTRODUCTION Turmeric (Curcuma longa L.) is one of the important spices grown in India and plays an important role in the national economy. Turmeric types can be grouped into three, based on the time taken to harvest, as short, medium and long-duration types. Short -duration types are known as Kasturi. They mature in seven months. Medium- duration Kesari types (Bontha) mature in eight months. Long-duration types mature in nine months and are superior to the above two groups in rhizome yield and other quality parameters. Flowering is rare in these types (Rao et al, 1975). Cultivated turmeric, C. longa is considered to be a sterile triploid with somatic chromosome number of sixty three (2n= 3x=63), while, C. aromatica is a tetraploid (2n=4x=84) and sets seeds. Curcuma langa being a sterile triploid, it is flowers fail to set seed. The variable success rate of seed set in ‘Prabha’ and ‘Prathiba’ (which are open - pollinated progenies in turmeric under Kerala conditions) by recombination breeding programme has been reported by Sasikumar et al (1994). Turmeric is asexually propagated with no seed production under Tamil Nadu conditions, restricting the breeder to rely on clonal selection, which is the major mode for its improvement. The first step in improvement of this clonally propagated crop is to exploit the variability existing among the land races and to create more variability through mutation and somaclonal variation. It being a polyploid (amphidiploid), use of mutagens in turmeric for inducing variability assumes greater significance. Success in mutation breeding depends largely on understanding the process of induction and recovery of mutants and screening methods for evaluating desired mutants. In turmeric, systematic attempts for induction of mutation are scanty and methodologies for induction and recovery of mutants are yet to be standardized. An attempt was therefore made to induce variability for days to maturity, yield and curing percentage by irradiation with gamma rays. MATERIAL AND METHODS The present investigation was carried out during 2000 - 2003 at the Department of Spices and Plantation Crops, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore. The experiment was laid out in Factorial Randomized Block Design and replicated twice under open field condition. Three genotypes, namely, Salem Local - G 1 (CL144), Alleppy finger turmeric - G 2 (CL146) and PTS 43 - G 3 (CL147) were used. Gamma ray source was Cobalt - 60 in 1000 Ci, J. Hort. Sci. Vol. 1 (2): 124-128, 2006 page 125 emitting 5000 rads per minute at the time of irradiation. Uniform sized finger rhizomes (approximately 10g each) were selected and cut into pieces, having 3 nodes per cutting. These rhizome bits, subjected to seven doses of gamma rays (1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 kR) along with control, were used as the planting material. Treated rhizome bits were planted on one side of the ridge at 5 cm depth at 45 x 15 cm spacing. After planting, a basal manurial dose comprising 25 kg N, 60 kg P and 18 kg k ha-1 was applied. It received a top dressing of 25 kg N and 18 kg k ha-1 at 30, 60, 90 and 120 days after planting. The field was irrigated before planting. Life irrigation was given on the third day of planting. Thereafter, irrigation was given at weekly intervals depending on weather and soil conditions. Ten plants in each genotype per replication were tagged randomly for recording observations and mean values were subjected to statistical scrutiny. Days to maturity The period from planting to harvest was recorded as the days taken to maturity. Yellowing and drying of the leaves as well as cracking of the soil were considered as indications of maturity. Yield per plant Fresh rhizomes harvested from each plant were weighed and the mean was expressed as grame (g) per plant. Curing per cent One hundred grames of fresh rhizomes from each treatment plot (comprising 30% mother rhizomes and 70% primary and secondary rhizomes) were boiled in pure water for 45-60 minutes till the rhizomes became soft and emitted the typical turmeric odour (Natarajan and Lewis, 1980). After boiling, the rhizomes were dried under sun until attaining 8% moisture content (Philip and Sethumadhavan, 1980). Curing per cent of the rhizomes was calculated using the following formula and was expressed as per cent: Weight of the cured rhizome Curing per cent = ——————————— x 100 Fresh weight of the rhizome RESULTS AND DISCUSSION Days to maturity vM 0 generation Among the different treatments in genotype G 1 (CL144), treatment T 3 (2.0 kR) exhibited earliness in days to maturity (223.11), followed by T 4 (2.5 kR) with 230.92 days. Delayed maturity (282.02 days) was seen in T 7 (4.0 kR), whereas, the control (T 0 ) took 235.23 days to mature. In G 2 (CL146), treatment T 3 (2.0 kR), followed by T 4 (2.5 kR), expressed earliness in days taken to mature (219.02 and 221.53, respectively) and T 7 (4.0 kR) showed delayed maturity (268.65 days), while, the control (T 0 ) registered 260.06 days. Similarly, in G 3 (CL147), treatment T 3 (2.0 kR) showed earliness in days to maturity (221.83) and T 7 (4.0 kR) recorded delayed maturity (288.10 days), whereas, the control (T 0 ) registered 246.13 days.The treatment combination G 2 T 3 (CL146, 2.0 kR) exhibited earliness in days to maturity (219.02), followed by G 2 T 4 (CL146, 2.5 kR) which required 221.53 days. Delayed maturity (288.10 days) was observed in G 3 T 7 (CL147, 4. 0 kR) (Table 1) vM 1 generation Among the different treatments, T 3 (2.0 kR) of the genotype G 1 (CL144) showed earliness in days to maturity (232.99). This was followed by T 3 (2.0 kR) of G 2 (CL146) which required 233.00 days. Delayed maturity (269.97 days) was expressed in T 7 (4.0 kR) of G 3 (CL147) followed by T 7 (4.0 kR) of G 1 (CL144) with 268.00 days, whereas the days to maturity exhibited in the control (To) of G 2 (CL146) was 248.17 days. The treatment combination G 1 T 3 (CL144, 2.0 kR) showed earliness in days to maturity (232.99 days), followed by G 2 T 3 (CL146, 2.0 kR) which required 233.42 days. Delayed maturity (269.97 days) was observed in G 3 T 7 (CL147, 4.0 kR) (Table 1). Yield per plant vMo generation Among the different treatments of G 1 (CL144), treatment T 3 (2.0 kR) produced the highest yield per plant (373.75 g) and the lowest yield (137.50 g) was recorded in T 7 (4.0 kR), whereas, the control (T 0 ) registered 301.50 g. In G 2 (CL146), treatment T 3 (2.0 kR) registered increased yield (266.25 g) and T 7 (4.0 kR) obtained decreased yield (63.75 g), while, the yield per plant observed in the control (T 0 ) was 97.88 g. Similarly, in G 3 (CL147), higher yield (241.25g) was expressed in T 3 (2.0 kR) and lower yield (127.50g) was seen in T 7 (4.0 kR), while, yield per plant obtained in the control (T 0 ) was 135.00 g. Genotype G 1 (CL144) exhibited higher yield per plant (373.75 g), followed by G 2 (CL146) and G 3 (CL147) with 266.25 and 241.25 g, respectively, in T 3 (2.0 kR). Increased yield (373.75 g) was noticed in the treatment combination G 1 T 3 (CL144, 2.0 kR), whereas, decreased yield (63.75 g) was observed in G 2 T 7 (CL146, 4.0 kR) (Table 2). J. Hort. Sci. Vol. 1 (2): 124-128, 2006 Impact of gamma rays on turmeric crop 125 page 126 vM 1 generation Among the treatments, T 3 (2.0 kR), T 4 (2.5 kR) and T 5 (3.0 kR) of G 1 (CL144) registered higher yield per plant (381.13, 360.00 and 330.12 g, respectively), whereas, a lower yield of 153.38g was obtained in T 7 (4.0 kR) as against the control (T 0 ) with 300.15 g. In G 2 (CL146), treatment T 3- (2.0 kR) produced the highest yield (260.19 g) and T 7 (4.0 kR) registered the lowest yield (73.15g) as against the control (T 0 ), with 100.02g. In G 3 (CL147), higher yield (250.12g) and lower yield (121.02g) were recorded in T 3 (2.0 kR) and T 7 (4.0 kR), respectively, as against the control (T 0 ) with 130.00g. Among the three genotypes, G 1 (CL144) produced an increase in yield (381.13 g), followed by G 2 (CL146) with 260.19 g and G 3 (CL147) with 250.12g in T 3 (2.0 kR), whereas, the control (T 0 ) of G 1 (CL144) obtained 300.15g. The treatment combination G 1 T 3 (CL144, 2.0 kR) produced the highest yield (381.13 g), whereas, the lowest yield (73.15 g) was registered in G 2 T 7 (CL146, 4.0 kR) (Table 3). Curing percentage vMo generation Among the different treatments of G 1 (CL144), T 3 (2.0 kR) followed by T 4 (2.5 kR) registered higher curing percent of 19.44 and 19.00, respectively and T 7 (4.0 kR) expressed a lower curing per cent of 15.22, whereas, the control (T 0 ) recorded 17.45 curing percent of. In G 2 (CL146), the highest curing per cent (19.00) was observed in T 3 (2.0 kR) and the lowest curing per cent (15.54) was obtained in T 7 (4.0 kR), while, curing percentage recorded in the control (T 0 ) was 17.05. In G 3 (CL147), treatment T 3 (2.0 kR) exhibited greater curing per cent (8.21) and T 7 (4.0 kR) showed lesser curing per cent (14.92), whereas, the control (T 0 ) expressed curing percent of 16.00 percent. Increased curing per cent (19.44) was obtained in G 1 (CL144), followed by G 2 (CL146) and G 3 (CL 147) with curing percent of 19.00 and 18.21, respectively in T 3 (2.0 kR) (Table 2). vM 1 generation Among the treatments, T 3 (2.0 kR), followed by T 4 (2.5 kR) of G 1 (CL144) obtained a higher curing per cent of 20.41 and 19.95, respectively. A lower curing per cent of 15.07 was exhibited in T 7 (4.0 kR) of G 3 (CL147). Among the three genotypes, G 1 (CL144) exhibited the highest curing per cent (20.41) followed by G 2 (CL146) and G 3 (CL 147) with curing percent of 19.57 and 18.39, respectively, in T 3 (2.0 kR), whereas, the control of G 1 (CL144) registered 18.32 curing percent of (Table 3). In the present investigation, treatment combination G 2 with 2.0 kR showed earliness in days to maturity compared to the other combinations. Delay in maturity was observed with increase in the dose of gamma rays. Delayed maturity at higher doses in the present investigation could be attributed to delay in plant growth caused by gamma rays. Physiological damage from gamma rays is generally higher in the initial stages of plant growth than at later stages. Induction of mutation generally occurs when DNA synthesis and chromosomal reproduction are in progress. Table 1. Effect of gamma irradiation in turmeric genotypes on days to maturity in vM 0 and vM 1 generation Genotype Treatment Days to maturity vM 0 generation vM 1 generation G 1 (CL144) T 1 (1.0kR) 270.20 251.32 T 2 (1.5kR) 260.88 245.59 T 3 (2.0kR) 223.11 232.99 T 4 (2.5kR) 230.92 233.42 T 5 (3.0kR) 234.13 239.98 T 6 (3.5kR) 271.08 261.88 T 7 (4.0kR) 282.02 268.00 T 0 (Control) 235.23 256.63 Mean 250.95 248.73 G 2 (CL146) T 1 (1.0kR) 257.11 245.00 T 2 (1.5kR) 249.69 240.09 T 3 (2.0kR) 219.02 233.00 T 4 (2.5kR) 221.53 235.15 T 5- (3.0kR) 227.09 235.00 T 6 (3.5kR) 264.09 250.13 T 7 (4.0kR) 268.65 253.88 T 0 (Control) 260.06 245.99 Mean 245.91 242.03 G 3 (CL147) T 1 (1.0kR) 266.80 263.82 T 2 (1.5kR) 246.01 250.01 T 3 (2.0kR) 221.83 241.97 T 4 (2.5kR) 227.28 242.00 T 5 (3.0kR) 242.28 244.22 T 6 (3.5kR) 269.72 268.12 T 7 (4.0kR) 288.10 269.97 T 0 (Control) 246.13 255.93 Mean 251.02 254.51 Grand Mean 249.30 248.17 CV(%) 5.92 4.51 vM 0 generation Sed CD(P=0.05) CD(P=0.01) T 8.38 17.33 23.51 G 5.13 10.61 14.40 GxT 14.51 30.01 40.73 vM 1 generation T 6.66 13.78 18.70 G 4.08 8.44 11.45 GxT 11.54 23.87 32.39 T-Treatment ; G-Genotype ; GxT- Genotype x Treatment J. Hort. Sci. Vol. 1 (2): 124-128, 2006 Usha Nandhini Devi & Chezhiyan 126 page 127 Mature or differentiated cells are incapable of responding to mutagenic treatments. Earliness in maturity may be attributed to the triggering of metabolic activities by lower doses of gamma rays. The trigger in metabolism would have resulted in changing the source – sink relationship, thereby, breaking the vegetative state at an advanced phase. The fact could be well understood from a study of the anatomy. The rhizome consists of multilayered, thin–walled cells in radial rows forming the cork tissue, with tangential epidermal cells, oblong in shape on the outside and thin walled parenchymatous cells of the cortex on the inside. The central cylinder of parenchymatous cells is separated from the cortex by a thin layer of oblong cells of the endoderm. Scattered throughout the parenchymatous tissue are starch granules (the dominant constituent) which are 15 to 30 mm in size, flat or disc shaped bodies, oleoresin cells containing oil and scattered particles of an orange– yellow component. All the important steps involved in the process of growth and development of turmeric rhizome were seriously influenced by growth period (maturity) which, in turn, was affected by an increase in the dose of gamma rays. This is in concordance with earlier reports by Jayachandran (1989) in ginger. Yield obtained on per plant basis was the highest at 2.0 kR, followed by 2.5 kR. Increased yield was noticed in the treatment combination G 1 with 2.0 kR. Increased yield at lower doses of gamma rays may be due to an increase in Table 2. Effect of gamma irradiation in turmeric genotypes on yield per plant (g) and curing per cent in vM 0 generation Genotype Treatment Yield per plant (g) Curing per cent G 1 (CL144) T 1 (1.0kR) 302.50 16.23 (23.75) T 2 (1.5kR) 325.00 18.00 (25.10) T 3 (2.0kR) 373.75 19.44 (26.16) T 4 (2.5kR) 353.75 19.00 (25.84) T 5 (3.0kR) 336.25 18.73 (25.64) T 6 (3.5kR) 226.25 15.75 (22.96) T 7 (4.0kR) 137.50 15.22 (23.38) T 0 (Control) 301.50 17.45 (24.69) Mean 294.56 17.48 (24.69) G 2 (CL146) T 1 (1.0kR) 111.25 16.73 (24.14) T 2 (1.5kR) 130.00 17.54 (24.75) T 3 (2.0kR) 266.25 19.00 (25.84) T 4 (2.5kR) 240.00 18.33 (25.34) T 5- (3.0kR) 181.25 17.92 (25.04) T 6 (3.5kR) 93.75 16.02 (23.59) T 7 (4.0kR) 63.75 15.54 (23.21) T 0 (Control) 97.88 17.05 (24.38) Mean 148.02 17.27 (24.54) G 3 (CL147) T 1 (1.0kR) 160.00 15.67 (23.31) T 2 (1.5kR) 173.75 16.73 (24.14) T 3 (2.0kR) 241.25 18.21 (25.20) T 4 (2.5kR) 221.25 17.83 (24.97) T 5 (3.0kR) 216.25 16.92 (24.28) T 6 (3.5kR) 136.25 15.00 (22.78) T 7 (4.0kR) 127.50 14.92 (22.72) T 0 (Control) 135.00 16.00 (23.57) Mean 176.41 16.41 (23.87) Grand Mean 206.33 17.05 (24.37) CV(%) 13.08 4.04 Yield per plant (g) Curing per cent SEd C.D C.D SEd C.D C.D (P=0.05) (P=0.01) (P=0.05) (P=0.01) T 14.99 31.01 42.08 0.54 1.12 1.52 G 9.18 18.99 25.77 0.33 0.69 0.93 GxT 25.96 53.71 72.89 0.94 1.94 2.64 T : Treatment G : Genotype, GxT : Genotype x Treatment Figures in parentheses indicate arc sine transformed values Table 3. Effect of gamma irradiation in turmeric genotypes on yield per plant (g) and curing per cent in vM 1 generation Genotype Treatment Yield per plant (g) Curing per cent G 1 (CL144) T 1 (1.0kR) 312.62 17.04 (24.37) T 2 (1.5kR) 321.43 18.90 (25.77) T 3 (2.0kR) 381.13 20.41 (26.85) T 4 (2.5kR) 360.00 19.95 (26.52) T 5 (3.0kR) 330.12 19.67 (26.32) T 6 (3.5kR) 253.17 16.54 (23.99) T 7 (4.0kR) 153.38 15.98 (23.56) T 0 (Control) 300.15 18.32 (25.34) Mean 301.50 18.35 (25.34) G 2 (CL146) T 1 (1.0kR) 123.00 17.23 (24.52) T 2 (1.5kR) 142.29 18.07 (25.15) T 3 (2.0kR) 260.19 19.57 (26.25) T 4 (2.5kR) 243.35 18.88 (25.75) T 5- (3.0kR) 200.42 18.46 (25.44) T 6 (3.5kR) 98.83 16.50 (23.96) T 7 (4.0kR) 73.15 16.01 (23.58) T 0 (Control) 100.02 17.56 (24.77) Mean 155.16 17.79 (24.93) G 3 (CL147) T 1 (1.0kR) 171.11 15.83 (23.44) T 2 (1.5kR) 194.22 16.90 (24.27) T 3 (2.0kR) 250.12 18.39 (25.39) T 4 (2.5kR) 248.00 18.01 (25.11) T 5 (3.0kR) 220.73 17.09 (24.41) T 6 (3.5kR) 152.00 15.15 (22.90) T 7 (4.0kR) 121.02 15.07 (22.84) T 0 (Control) 130.00 16.16 (23.70) Mean 185.90 16.45 (20.96) Grand Mean 225.90 17.57 (24.76) CV(%) 13.00 4.04 Yield per plant (g) Curing per cent SEd C.D C.D SEd C.D C.D (P=0.05) (P=0.01) (P=0.05) (P=0.01) T 15.43 31.93 43.33 0.55 1.14 1.55 G 9.45 19.55 26.53 0.34 0.70 0.95 GxT 26.73 55.30 75.05 0.96 1.98 2.68 T : Treatment G : Genotype, GxT : Genotype x Treatment Figures in parentheses indicate arc sine transformed values J. Hort. Sci. Vol. 1 (2): 124-128, 2006 Impact of gamma rays on turmeric crop 127 page 128 the level of enzymes, which activate metabolism of the cells responsible for translocation of metabolites from source to sink. Lower doses of gamma rays may have enhanced the enzymatic processes involved in plant growth and development such as proper stomatal functioning, photosynthetic efficiency in terms of net assimilation rate and partitioning efficiency from the source to the sink, and, in related biochemical reactions. Yield per plant decreased as the dose of gamma rays increased. Low yield at increased dose obtained in the present investigation can be attributed to reduction plant in growth, leaf area and size and growth of rhizomes, particularly, secondary rhizomes by gamma rays. Increased dose adversely affected tiller and leaf production and height of the plant, especially, during the early stages of growth. As the growth period advanced, the plants could, more or less, recover from the adverse effects during early stages noted in the above characters. However, recovery in growth achieved during the later stages of growth did not appear to have sufficient contribution to rhizome development. This may be the reason for the yield that resulted at higher doses of gamma rays, irrespective of the fact that the plants could recover from the shock of gamma ray treatments later in their growth period. Similar line of work had been reported by Raju et al (1980) who reported weaker and elongated underground rhizomes in ginger with application of 2.0 kR gamma rays. In Costus speciosus, Gupta et al (1982) observed increased rhizome production at 1.5 kR gamma ray treatment. However, the yield of rhizomes decreased at higher doses of 2.0, 2.5 and 3.0 kR. Shah et al (1982) observed high yields in turmeric as a result of X-ray irradiation. Significant variation was noticed in curing percentage among treatments. Curing per cent was higher in the treatment 2.0 kR, followed by 2.5 kR and was found to decrease with increase in the dose of gamma rays. Variation in curing percentage among the treatments was chiefly due to genetic factors rather than the type of processing used. Expression of low curing per cent at higher doses of gamma rays may be attributed to lesser resource utilization by the rhizomes at the rhizome bulking stage as a result of gamma irradiation. Resource utilization was affected due to a lower net assimilation rate, which was mainly characterized by enhanced physiological parameters such as crop growth rate, relative growth rate, photosynthetically active radiation (PAR) and higher net assimilation rate during the early stages of plant growth and rhizome development upto seven months after planting. Present findings are in corroboration with earlier work carried out by Subramanian et al (2002) in CO 1 and BSR 1 clones of turmeric. Higher curing per cent was mainly due to production of slender rhizomes, perhaps due to lower moisture retention at harvest. Low curing per cent was mainly due to the fact that feeder roots are present near the soil surface under irrigated conditions, and these absorb more water and ought to have higher moisture content. As a result, the rhizome becomes plump and after curing, the yield gets reduced. This is in accordance with previous work of Philip (1983) and Reddy et al (1989) in turmeric. REFERENCES Gupta, M.N., Lakshmi.V, DixitV. S and Srivastava. S.N 1982. Gamma ray induced variability in Costus speciosus. Prog. Hort., 14: 193-197. Jayachandran, B.K. 1989. Induced mutations in ginger. Ph.D. Thesis submitted to Kerala A g r i c u l t u r a l University, Vellanikara, Trissur. Natarajan, C.P. and Lewis. Y. S. 1980. Technology of ginger and turmeric. 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Shah, H.A., Seemanthini,R, Arumugam.R Muthuswamy.S and Khader.J.B.M 1982. CO1 turmeric - a high yielding mutant turmeric. South Ind. Hort., 30: 276-277. Subramanian, S., Subbiah.A, Vijayakumar.M and Saraswathy.S 2002. Growth and physiological attributes of turmeric varieties (Curcuma longa L.) BSR-1 and CO1 under Coimbatore conditions. In: Proceedings of seminar on strategies for production and export of spices, Oct’ 24-27. IISR, Calicut. p. 18. J. Hort. Sci. Vol. 1 (2): 124-128, 2006 Usha Nandhini Devi & Chezhiyan 128 (MS Received 12 April 2006 , Revised 21 September 2006)