CHAPTER IVEXPERIMENTAL RESULTSSalinity (0.05M NaCl):The difference in shoot length of seedlings in salinity (0.05M NaCl) test was highly significant among 12 rice genotypes. Shoot length ranged from 9.95 cm (TRY (R) 2) to 12.30 cm (FL 478). The mean value of shoot length under 0.05M concentration was 11.02cm. Among 12 genotypes, BPT 5204 (9.97 cm) was found to be susceptible. At salinity level of 0.05 M NaCl, six genotypes viz., TRY 1, TNAU Rice TRY 3, FL 478, TR 10 002, TR 10 005 and TR 10 007 recorded statistically superior value for shoot length [Table 2(a)].The difference in root length of seedlings in salinity (0.05M NaCl) test was highly significant among 12 rice genotypes. Root length ranged from 15.21 cm (I.W.Ponni) to 24.32 cm (Vyttila 6). The mean value for root length under 0.05M was 20.19 cm. Among 12 genotypes I.W.Ponni (15.21 cm) was found to be susceptible. At salinity level of 0.05M NaCl, eight genotypes viz., TRY 1, TRY (R) 2, TNAU Rice TRY 3, Vyttila 6, FL 478, TR 10 002,TR 10 003 and TR 10 007 recorded statistically superior value for root length [Table 2(a)].Germination percentage ranged from 62 (BPT 5204) to 96 percent (TNAU Rice TRY 3, FL 478 and TR 10 007). Mean value for germination percentage at 0.05M NaCl was 82 percent. The difference in germination percentage of different rice genotypes exposed to 0.05M NaCl concentration was highly significant. The genotypes TRY 1, TRY (R) 2, TNAU Rice TRY 3, CSR 23, FL 478, TR 10 003 and TR 10 007 recorded statistically superior value for germination percentage [Table 2(a)].The seedling dry mater production ranged from 0.13 mg (I.W.Ponni) to 0.26 mg (FL 478). The mean value was 0.18 mg. The genotype I.W.Ponni (0.13 mg) showed lower dry mater production. Among 12 genotypes TRY 1, TNAU Rice TRY 3, Vyttila 6, CSR 23, FL 478 and TR 10 005 recorded statistically superior value for dry matter production [Table 2(a)].The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 927.08 (TR 10 003) to 1180.80 (FL 478). Mean vigour index with reference to shoot length 914.95 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which eight genotypes viz., TRY 1,TRY (R) 2, TNAU Rice TRY 3,CSR 23,FL 478, TR 10 003, TR 10 007 and TR 10 005 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 973.44 (I.W.Ponni) to 2200.64 (TRY (R) 2). Mean vigour index with reference to root length 1680.10 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which six genotypes viz., TRY 1,TRY(R) 2, TNAU Rice TRY 3, FL 478, TR 10 003 and TR 10 007 recorded statistically superior than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 8.184 (BPT 5204) to 13.064 (TNAU Rice TRY 3). Mean vigour index with reference to dry matter production 20.80 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which two rice genotypes viz., TNAU Rice TRY 3 and FL 478 recorded statistically superior than other genotypes.Salinity (0.1M NaCl):The difference in shoot length of seedlings in salinity (0.1M NaCl) test was highly significant among 12 rice genotypes. Shoot length ranged from 6.89 cm (BPT 5204) to 11.93 cm (TR 10 005 and TR 10 007). The mean value of shoot length under 0.05M concentration was 10.02 cm. Among 12 genotypes, BPT 5204 (6.89 cm) was found to be susceptible. At salinity level of 0.1M NaCl, five genotypes viz., TRY 1, FL 478, TR 10 002, TR 10 005 and TR 10 007 recorded statistically superior value for shoot length [Table 2(b)].The difference in root length of seedlings in salinity (0.1M NaCl) test was highly significant among 12 rice genotypes. Root length ranged from 13.28cm (BPT 5204) to 22.09 cm (Vyttila 6). The mean value for root length under 0.1M was 18.86cm. Among 12 genotypes, BPT 5204 (13.28 cm) was found to be susceptible. At salinity level of 0.1M NaCl, eight genotypes viz., TRY 1,TRY (R) 2, TNAU Rice 3, Vyttila 6, FL 478, TR 10 002, TR 10 003 and TR 10 007 recorded statistically superior value for root length [Table 2(b)].Germination percentage ranged from 58 (BPT 5204) to 94 percent (FL 478). Mean value for germination percentage at 0.1M NaCl was 78 percent. The difference in germination percentage of different rice genotypes exposed to 0.1M NaCl concentration was highly significant. The genotypes TRY 1, TRY (R) 2, TNAU Rice TRY 3, CSR 23, FL 478 and TR 10 007 recorded statistically superior value for germination percentage [Table 2(b)].The seedling dry mater production ranged from 0.08 mg (I.W.Ponni) to 0.24 mg (FL 478). The mean value was 0.18 mg. The genotype I.W.Ponni (0.08 mg) showed lower dry mater production. Among 12 genotypes, TRY 1, TNAU Rice TRY 3, Vyttila 6, CSR 23, FL 478 and TR 10 005 recorded statistically superior value for dry matter production.The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 413.40 (BPT 5204) to 1118.6 (FL 478). Mean vigour index with reference to shoot length was 780.44 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which eight genotypes viz., TRY 1,TRY(R) 2, TNAU Rice TRY 3, CSR 23, FL 478, TR I0 003, TR 10 007 and TR 10 005 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 797.4 (I.W.Ponni) to 1972.12 (FL 478). Mean vigour index with reference to root length was 1481.15 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which six genotypes viz., TRY 1, TRY(R) 2, TNAU Rice TRY 3, FL 478, TR 10 003 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 4.800 (I.W.Ponni) to 22.372 (FL 478). Mean vigour index with reference to dry matter production 14.01 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which six genotypes viz., TRY 1, TNAU Rice TRY 3, CSR 23, FL 478, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.Salinity (0.15M NaCl):The difference in shoot length of seedlings in salinity (0.15M NaCl) test was highly significant among 12 rice genotypes. Shoot length ranged from 2.19 cm (I.W.Ponni) to 7.70cm (FL 478). The mean value of shoot length under 0.15M concentration was 5.57cm. Among 12 genotypes, I.W.Ponni was found to be susceptible. At salinity level of 0.15 M NaCl, nine genotypes viz., TRY 1, TRY(R) 2, TNAU Rice TRY 3, CSR 23, FL 478, TR 10 002, TR 10 005 and TR 10 007 recorded statistically superior value for shoot length [Table2(c)].The difference in root length of seedlings in salinity (0.15 M NaCl) test was highly significant among 12 rice genotypes. Root length ranged from 11.21cm (BPT 5204) to 22.78 cm (Vyttila 6). The mean value for root length under 0.15M was 16.42cm. Among 12 genotypes, BPT 5204 (11.21cm) was found to be susceptible. At salinity level of 0.15M NaCl, seven genotypes viz., TRY 1, TRY (R) 2, TNAU Rice TRY 3, Vyttila 6, TR 10 002, TR 10 003 and TR 10 007 recorded statistically superior value for root length.Germination percentage ranged from 42 (BPT 5204) to 90 percent (TNAU Rice TRY 3). Mean value for germination percentage at 0.15M NaCl was 72.41. The difference in germination percentage of different rice genotypes exposed to 0.15M NaCl concentration was highly significant. The genotypes TRY 1,TRY(R) 2, TNAU Rice TRY 3, FL 478, TR 10 003 and TR 10 007 recorded statistically superior value for germination percentage.The seedling dry mater production ranged from 0.07 mg (I.W. Ponni) to 0.22 mg (TRY 1). The mean value was 0.156mg. The genotype I.W. Ponni (0.07 mg) showed lower dry mater production. Among 12 genotypes, TRY 1, TNAU Rice TRY 3, Vyttila 6, CSR 23, FL 478 and TR 10 005 recorded statistically superior value for dry matter production.The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 109.5 (I.W.Ponni) to 677.6 (FL 478). Mean vigour index with reference to shoot length 425.65 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which eight genotypes viz., TRY 1, TRY (R) 2, TNAU Rice TRY 3, CSR 23, FL 478, TR I0 002, TR 10 003 and TR 10 007 recorded as statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 470.88 (BPT 5204) to 1653.78 (TRY (R)2). Mean vigour index with reference to root length 1230.05. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which seven genotypes viz., TRY 1, TRY(R) 2, TNAU Rice TRY 3, FL 478, TR 10 003, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 3.650 (I.W.Ponni) to 18.810 (TNAU Rice TRY 3). Mean vigour index with reference to dry matter production 11.819. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which six genotypes viz., TRY 1, TNAU Rice TRY 3, CSR 23,FL 478, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.Salinity (0.2M NaCl):The difference in shoot length of seedlings in salinity (0.2M NaCl) test was highly significant among 12 rice genotypes. Shoot length ranged from 0.67 cm (Vyttila 6) to 7.70 cm (FL 478). The mean value of shoot length under 0.2M concentration was 5.57cm among 12 genotypes, I.W.Ponni (1.98 cm) was found to be susceptible. At salinity level of 0.2M NaCl, nine genotypes viz., TRY 1, TRY(R) 2, TNAU Rice TRY 3,CSR 23,FL 478, TR 10 002, TR 10 005 and TR 10 007 recorded statistically superior value for shoot length [Table 2(d)].The difference in root length of seedlings in salinity (0.2M NaCl) test was highly significant among 12 rice genotypes. Root length ranged from 6.98 cm (BPT 5204) to 22.78 cm (Vyttila 6). The mean value for root length under 0.2M was 16.42cm. Among 12 genotypes, BPT 5204 (11.21cm) was found to be susceptible. At salinity level of 0.2 M NaCl, seven genotypes viz., TRY 1,TRY (R) 2, TNAU Rice TRY 3, Vyttila 6, TR 10 002, TR 10 003 and TR 10 007 recorded statistically superior value for root length.Germination percentage ranged from 42 (BPT 5204) to 90 percent (TNAU Rice TRY 3). Mean value for germination percentage at 0.2M NaCl was 72.41. The difference in germination percentage of different rice genotypes exposed to 0.2M NaCl concentration was highly significant. The genotypes TRY 1, TRY(R) 2, TNAU Rice TRY 3, FL 478, TR 10 003 and TR 10 007 recorded statistically superior value for germination percentage.The seedling dry matter production ranged from 0.07 mg (I.W.Ponni) to 0.21 mg (TRY 1). The mean value was 0.16 mg. The genotype I.W.Ponni (0.07 mg) showed lower dry mater production. Among 12 genotypes, TRY 1, TNAU Rice TRY 3, Vyttila 6, CSR 23, FL 478 and TR 10 005 recorded statistically superior value for dry matter production.The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 33.05 (Vyttila 6) to 281.36 (TNAU Rice TRY 3). Mean vigour index with reference to shoot length 157.18 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which seven genotypes viz., TRY 1, TRY (R) 2, TNAU Rice TRY 3, CSR 23, TR I0 002, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 267.6 (BPT 5204) to 1088.96 (TRY (R) 2). Mean vigour index with reference to root length 731.54 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which eight genotypes viz., TRY 1, TRY(R) 2, TNAU Rice TRY 3, Vyttila 6, FL 478, TR 10 003, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of the seedlings ranged from 1.950 (BPT 5204) to 16.512 (TRY (R) 2). Mean vigour index with reference to dry matter production 9.71 among 12 genotypes. The effect of salt stress on vigour index of 12 rice genotypes were assessed, in which six genotypes viz., TRY 1, TRY (R) 2, TNAU Rice TRY 3, CSR 23, FL 478 and TR 10 005 recorded statistically superior value than other genotypes.Accelerated ageing (2 days):The difference in shoot length of seedlings in accelerated ageing (2 days) test showed [Table 3(a)] highly significant difference among 10 rice genotypes. Shoot length ranged from 10.28cm (ADT 36) to 12.98cm (TR 10 007). The mean value of shoot length under 2 days was 11.42cm. Among 10 genotypes, ADT 36 recorded as poorest performer. Five genotypes viz., CR 1009, BPT 5204, TR 10 003, TR 10 005 and TR 10 007 recorded statistically superior value for shoot length.The difference in root length of seedlings in accelerated ageing (2 days) test showed [Table 3(a)] highly significant difference among 10 rice genotypes. Root length ranged from 18.28 cm (TR 10 005) to 25.32cm (TR 10 003). The mean value of root length under 2 days was 21.14 cm. Among 10 genotypes, TR 10 005 showed poor performance. Three genotypes viz., ADT 37, TR 10 003 and TR 10 007 recorded statistically superior value for root length.Germination percentage ranged from 86 (CR 1009) to 96 percent (ADT 36). Mean value for germination percentage was 91.60 percent. The genotype ADT 36 recorded statistically superior than remaining genotypes with reference to germination percentage.The seedling dry mater production ranged from 0.12 mg (BPT 5204) to 0.15mg (TR 10 005). The mean value was 0.15 mg. Four genotypes CR 1009, TR 10 002, TR 10 003 and TR 10 005 recorded statistically superior value for dry matter production.The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of 2 days aged seeds of 10 rice genotypes were taken into consideration in which the Vigour index of seedlings ranged from 975.72 (TR 10 002) to 1168.20 (TR 10 007). Mean vigour index with reference to shoot length 1044.88. Out of 10 genotypes, five genotypes viz., CO 43, BPT 5204, TR 10 003, TR 10 005 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of two days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 1645.20 (TR 10 005) to 2329.43 (TR 10 003). Mean vigour index with reference to root length was 1970.63. Out of 10 genotypes, four genotypes viz., ADT 36, ADT 37, TR 10 003 and TR 10 007 recorded statistically superior than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Two days aged seeds of 10 rice genotypes were taken into consideration in which the vigour index of seedlings ranged from 10.710 (BPT 5204) to 15.548 (TR 10 003). Mean vigour index with reference to dry matter production was 13.36. Out of 10 genotypes, five genotypes viz., CO 43, CR 1009, TR 10 003, TR 10 005 and TR 10 002 recorded statistically superior value than other genotypes.Accelerated ageing (3 days): The difference in shoot length of seedlings in accelerated ageing (3 days) test showed [Table 3(b)] highly significant difference among 10 rice genotypes. Shoot length ranged from 08.35 cm (TR 10 003) to 11.35 cm (TR 10 007). The mean value of shoot length under 3 days was 09.59 cm. Four genotypes viz., ADT 36, ADT 37, CR 1009 and TR 10 007 recorded statistically superior value for shoot length.The difference in root length of seedlings in accelerated ageing (3 days) test showed [Table 3(b)] highly significant difference among 10 rice genotypes. Root length ranged from 17.38 cm (TR 10 005) to 24.92 cm (TR 10 003). The mean value of root length under 3 days was 20.06 cm. Four genotypes viz., ADT 37, BPT 5204, TR 10 003, and TR 10 007 recorded statistically superior value for root length.Germination percentage ranged from 82 (BPT 5204) to 96 percent (ADT 36). Mean value for germination percentage was 89 percent. The genotypes ADT 36 and TR 10 002 recorded statistically superior value for germination percentage.The seedling dry mater production ranged from 0.11 mg (BPT 5204) to 0.16 mg (TR 10 005). The mean value was 0.14 mg. Five genotypes viz., CO 43, CR 1009, TR 10 002, TR 10 003 and TR 10 005 recorded statistically superior value for dry matter production.The computed vigour index values with reference to shoot length showed highly significant difference among the rice genotypes. Vigour index of 3 days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 732.26 (BPT 5204) to 998.80 (TR 10 007). Mean vigour index with reference to shoot length was 855.43. Out of 10 genotypes, four genotypes viz., ADT 36, ADT 37, TR 10 002 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of 3 days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 1494.68 (TR 10 005) to 2192.96 (TR 10 003). Mean vigour index with reference to root length was 1785.44. Out of 10 genotypes, four genotypes viz., ADT 36, ADT 37, TR 10 003 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of 3 days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 8.856 (BPT 5204) to 14.006 (TR 10 002). Mean vigour index with reference to dry matter production was 12.42. Out of 10 genotypes, four genotypes viz., CO 43, TR 10 003, TR 10 005 and TR 10 002 recorded statistically superior value than other genotypes.Accelerated ageing (4 days):The difference in shoot length of seedlings in accelerated ageing (4 days) test showed [Table 3(c)] highly significant among 10 rice genotypes. Shoot length ranged from 07.88 cm (CO 43) to 11.26 cm (TR 10 007). The mean value of shoot length under four days was 8.67 cm. Three genotypes viz., BPT 5204, TR 10 002 and TR 10 007 recorded statistically superior value over other genotypes.The difference in root length of seedlings in accelerated ageing (4 days) test showed [Table 3(c)] highly significant among 10 rice genotypes. Root length ranged from 17.18 cm (ADT 44) to 23.28 cm (TR 10 003). The mean value of root length under 4 days was 19.15 cm. Four genotypes viz., ADT 37, BPT 5204, TR 10 003 and TR 10 007 recorded statistically superior over other genotypes.Germination percentage ranged from 76 (BPT 5204) to 94 percent (ADT 36). Mean value for germination percentage was 86 percent. The genotypes ADT 36, ADT 37 and TR 10 002 recorded statistically superior value for germination percentage.The seedling dry mater production ranged from 0.10 mg (BPT 5204) to 0.16 mg (TR 10 005). The mean value was 0.13 mg. Five genotypes CO 43, TR 10 007, TR 10 002, TR 10 003 and TR 10 005 recorded statistically superior value than other genotypes.The computed vigour index values with reference to root length showed highly significant difference among the rice genotypes. Vigour index of 4 days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 1452.36 (TR 10 005) to 2002.08 (TR 10 003). Mean vigour index with reference to root length was 1657.32. Out of 10 genotypes, Five genotypes viz., ADT 36, ADT 37, TR 10 002, TR 10 003 and TR 10 007 recorded statistically superior value than other genotypes.The computed vigour index values with reference to dry matter production showed highly significant difference among the rice genotypes. Vigour index of 4 days aged seeds of 10 rice genotypes were taken into consideration in which the seedlings ranged from 7.676 (BPT 5204) to 13.524 (TR 10 002). Mean vigour index with reference to dry matter production was 11.63. Out of 10 genotypes, Five genotypes viz., CO 43, TR 10 003, TR 10 005, TR 10 002 and TR 10 007 recorded statistically superior than other genotypes.Drought:Rice genotypes subjected to drought stress condition with reference to shoot length recorded the minimum length of 2.5 cm (ADT 43) and the maximum length of 4.35 cm (I.W.Ponni). There were no significant difference among 10 rice genotypes.Rice genotypes with reference to root length, recorded the minimum length of 5.1cm (CO 43), and the maximum length of 9.25 cm (TR 10 035). The mean value was 7.34 cm. Among 10 genotypes CO 43 (5.10cm) and I.W.Ponni (5.50cm) were found to be susceptible genotypes. The genotypes TR 10 035 (9.25 cm), TR 10 003 (8.95 cm), TR 10 032 (8.60 cm), TR 10 005 (8.30cm), TRY (R) 2 (8.10 cm) and TR 10 012 (7.35 cm) recorded statistically superior value for root length.The seedling dry mater production ranged from 45.50 mg (ADT 43) and (I.W.Ponni) to 83.50 mg (TR 10 012). The mean value was 62.10 mg. The genotypes ADT 43 and I.W.Ponni (45.50 mg) showed lower dry mater production. Among 10 genotypes TR 10 012 recorded statistically superior value than other genotypes.

Discussion

CHAPTER VDISCUSSIONSALINITY: Per se performance of any trait is important and hence, added value should be given for evaluating the trait under investigation as it is the realized value. When 12 genotypes evaluated for root length under 0.1 M concentration, 10 genotypes registered statistically longer root length when compared to two susceptible genotypes viz., BPT 5204 (9.97 ), I.W Ponni( ). It is revealed that longer root length posses the tolerance to abiotic stresses like drought, salinity with the above parameter study as yardstick only four genotypes viz., Vyttila6 (22.09cm), TRY (R) 2(21.09cm), FL 478 (20.98cm) and TNAU Rice TRY 3 (20.92cm), excelled for the trait. Out of 10 genotypes, those four genotypes were of immense value as they possessed desirable root trait. The similar trend was found when 12 genotypes under other concentrations viz.,0.05,0.15,0.2M. The reduction in root length was observed as salt concentration increased. It is highly observed that that two genotypes Vyttila 6, TRY (R) 2 alone showed no substantial reduction in root length under 0.1M treatment. Similar results but only two genotypes Vyttila 6, TRY (R) 2 excelled for root length trait under 0.1M treatment. Hence those two genotypes Vyttila 6 and TRY (R) 2 could be used as potential parents in the hybridization programme along with elite variety in a suitable mating design to infuse salinity tolerance coupled with yield in order to bridge the gap between potential and realized value. When 12 genotypes evaluated for shoot length under 0.1M concentration 10 genotypes viz.,(other than BPT 5204 and I.W.Ponni) registered statistically higher shoot length when compared to two susceptible genotypes viz., BPT 5204 and I.W.Ponni. Out of 10 genotypes, only five genotypes viz., TRY 1, FL 478, TR 10 002, TR 10 005 and TR 10 007, excelled for the trait. Those five genotypes were of immense value as they possessed desirable shoot trait. The similar findings were observed when 12 genotypes under other concentrations viz., 0.05, 0.15, 0.2M. As salt concentration increased the reduction in shoot length was observed. It is observed that one genotype FL 478 alone showed no substantial reduction in shoot length under 0.1M treatment. Similar trend but only one genotype FL 478 excelled for shoot length trait under treatment. Hence those genotype FL 478 could be used as potential parents in the hybridization programme along with elite variety in a suitable mating design to infuse salinity tolerance coupled with yield. In order to bridge the gap between potential and realized value. The similar trend was found when 12 genotypes under other concentrations viz., 0.05, 0.15, 0.2M. Germination percentages were inversely related to salt concentration level. The percentage of germination significantly decreased in all varieties due to increasing salinity level. Above optimum level a higher germination percentage of more than 85% was observed from the varieties TRY(R) 2, TNAU Rice TRY 3 and FL 478, which were statistically superior. The lowest germination percentage less than 60% was observed for the varieties of BPT 5204, I.W.Ponni and Vyttila 6. The dry matter production were significantly decreased in all genotypes due to increasing salinity level. The results of ANOVA for salt tolerance showed significant differences among genotypes for all traits viz.,shoot length, root length, germination percentage and dry matter production. The genotypes responded differently to increasing salinity levels. The result showed that there was a progressive decrease in the growth parameters of rice plant with an increase in salt concentration. Also salinity stress affected all the growth parameters and this reduction was high at increasing salinity levels. Salt stress may reduce plant growth by water deficit, ion toxicity, ion imbalance, or combination of any of these factors. ACCELERATED AGEING: A rapid screening test (Accelerated Ageing at 40C and 95% RH) has been developed that can evaluate rice seed tolerance for adverse environmental conditions. The degree of tolerance for accelerated ageing treatment has been related to the survivability of the seed in storage. In case of accelerated ageing conditions, when 10 genotypes evaluated for growth parameters, the genotype TR10 007 registered statistically higher shoot length when compared to all other genotypes. Similarly for root length, the genotype TR 10 003 registered statistically superior, after 2, 3 & 4 days of ageing. The germination percentage and dry matter production were drastically reduced when days increase for accelerated ageing treatment could help the breeders to screen the potential cultivar to resist seed deterioration during storage. The result indicates that rice cultivar differ significantly in their ability to maintain seed viability during artificial ageing. Further investigation are needed to determine the inheritance of seed tolerance for ageing stress in rice. Dormancy appears to have positive effects on the tolerance of seed for ageing. As the ageing treatments were extended to 72 hours, the growth efficiency declined markedly in all the varieties. The declination in growth efficiency at 72 hours ageing was due to physiological and biochemical factors associated with the adverse effect of accelerated ageing on germination and seedling growth .

DROUGHT: Ten rice genotypes were evaluated for moisture stress at 14 days old seedlings, there was no significant differences among shoot length. The drought is a complex phenomenon and controlled by many genes. It is much influenced by the environment and genotype environment interaction. Drought tolerance is influenced by desirable shoot and root traits. However, the root trait play a significant role for drought tolerance in rice. Longer the root better is the tolerance, because the genotypes possessing longer root can absorb water present in the subsoil also. The length of the root determine the drought tolerance as the lengthier root penetrates in to the subsoil and absorb to water which enables better establishment. The standard variety for fine grain at Tamil Nadu (I.W.Ponni) was taken as the check and assessed the performance of other genotypes for root length. Six genotypes viz., TR10 035, TR10 032, TR10 005, TRY (R) 2 and TR10 012 statistically possessed longer root length when compared to I.W.Ponni (5.50cm). Among six genotypes TRY (R) 2 alone, is the short duration variety. Hence all the above 6 genotypes might be included in a hybridization programme to transfer the drought tolerance in to the high yielding variety. It is emphasized that the genotype TRY (R) 2 besides possessing inherent capacity of drought tolerance also possessing earliness. The earliness of any crop variety would act as avoidance mechanism for drought tolerance.

Determination of growth parametersSeedling shoot length:Seedlings from each replication were carefully removed at random on 14th day and shoot length was measured from the collar region to be tip of the shoot and expressed in cm.Seedling root length: Root length of the seedlings were measured from the base of the stem to the tip of the root and expressed in cm.Germination percentage: The ability of germination was recorded on 14th day and number of germinated seeds were expressed in percentage. Number of germinated seeds Germination percentage = --------------------------------------------- 100 Total Number of seeds Vigour index: The vigour index of the seedlings were calculated using the following formula proposed by Abdul Baki and Anderson (1973). VI1 = Germination % shoot length VI2 = Germination % root length VI3= Germination % dry mater production.

Table 1(b): pH and EC for different salt concentrations :Salt concentration(M NaCl)pHEC (dSm-1)

0.056.5504.97

0.106.4309.28

0.156.3511.58

0.206.2113.03

STATISTICAL ANALYSISAnalysis of variance (ANOVA)Analysis of variance (ANOVA) was done separately for each trait for all treatments. The model of the analysis of variance is given below: Sourcesd.fMSSF

Replicationsr-1RMSSTMSS/EMSS

Treatmentst-1TMSS

Error(r-) (t-1)EMSS

Total(rt-1)

where, t = number of treatments (genotypes) r = number of replications The standard error was calculated as S. E = EMSS/r Significance of treatment mean square and replication mean square were tested by comparing with error mean squares referring to F table value at 5 % level of probability.

Determination of growth parametersSeedling shoot length:Seedlings from each replication were carefully removed at random on 14th day and shoot length was measured from the collar region to be tip of the shoot and expressed in cm.Seedling root length: Root length of the seedlings were measured from the base of the stem to the tip of the root and expressed in cm.Germination percentage: The ability of germination was recorded on 14th day and number of germinated seeds were expressed in percentage. Number of germinated seeds Germination percentage = --------------------------------------------- 100 Total Number of seeds Vigour index: The vigour index of the seedlings were calculated using the following formula proposed by Abdul Baki and Anderson (1973). VI1 = Germination % shoot length VI2 = Germination % root length VI3= Germination % dry mater production.

Table 1(b): pH and EC for different salt concentrations :Salt concentration(M NaCl)pHEC (dSm-1)

0.056.5504.97

0.106.4309.28

0.156.3511.58

0.206.2113.03

STATISTICAL ANALYSISAnalysis of variance (ANOVA)Analysis of variance (ANOVA) was done separately for each trait for all treatments. The model of the analysis of variance is given below: Sourcesd.fMSSF

Replicationsr-1RMSSTMSS/EMSS

Treatmentst-1TMSS

Error(r-) (t-1)EMSS

Total(rt-1)

where, t = number of treatments (genotypes) r = number of replications The standard error was calculated as S. E = EMSS/r Significance of treatment mean square and replication mean square were tested by comparing with error mean squares referring to F table value at 5 % level of probability.