The four sets of investigations were undertaken for two years to study (i) agro-management techniques for increasing hybrid seed yield in production plot, (ii) study the synchronization methods of flowering of hubris and its parental lines of hybrid, (iii) assessing the genetic purity of parental lines and hybrids using conventional and molecular approaches and (iv) discuss the potentional implications of above findings in hybrid seed production programme of the country. The material in first two sets comprised of A, B and R lines of hybrid Pant Sankar Dhan 3 and third and fourth sets consisted of (a) grow out test of four hybrid seed lots and, (b) SSR and STS maker analysis of 10 hybrid seed lots and their 13 parental lines. Sixteen agro-techniques studied had a combination of varying seed rates, seeding depths, N dosage and application methods in nursery and N dose and their application methods and population density in the main field. Data on days to 50% flowering, (DF), plant height (PH), tillers/hill (TN), panicles/hill (PN), panicle length (PL), spikelets/panicle (SP), per cent panicle exsertion (PPE), panicles/m2 (PMS), per cent seed set (PSS), 1000-seed weight (SW), seed yield/hill (SYH) and seed yield/m2 area (SYM) of the seed parent and DF, PH, TN, PN, PL, SYH and SYM for the pollen parent were recorded. Results from the pooled data revealed highly significant variances due to treatments for all the characters of A and R lines of the hybrid. Interaction effects between treatments and year on seedling growth parameters were significant for most of the traits of pollen parent only. Maximum TN were produced between 14 to 21 DAT which declined rapidly thereafter. The best agro management technique yielded 4.3 t/ha of hybrid seed and 7.8t/ha for restorer (male) parent in seed production plot. It involved lower seed rate (15 g/m2 area), deeper (5.0 cm) seeding and higher N (150 kg/ha) dose with three split applications in the nursery and high N (210 kg/ha) with four splits and transplanting two seedlings/hill in A/R production plot.
Seeding sequence of parental lines of Pant Sankar Dhan 3 for multiplication of A line (A/B) and hybrid seed production (A/R) was determined using three methods of synchronization. In growth duration difference (GDD) method, B and R lines are earlier on an average of three planting dates by 5 and 4 days with respect to their seed parent. Effective accumulated temperature (EAT) for flowering of A, B and R lines are 1477.53, 1397.13 and 1421.66oC. Leaf number (LN) for flowering of A, B and R lines are 16.50, 14.96 and 15.30, respectively. For synchronization, seeding of B and R lines is suggested when the A line attains LN of 1.54 and 1.2, respectively for A/B and A/R production. Study revealed greater consistency in flowering days in CMS line with LND method, as compared to other two methods. It suggests LND method to be more reliable across the planting dates followed by EAT and GDD to predict synchronization between parental lines of hybrids.
Grow out test identified the hybrids as well as the traits with maximum percentage off-type plants. Flowering was to be most useful trait during selection/evaluation of a hybrid and genotype for genetic purity. DNA markers RM 154, RM 164, RM 234, RM 258 and RM 519 displayed polymorphism over all 13 lines and nine hybrids studied and suggested them as referral marker for authentication, purity estimation and protection of hybrids. Within 13 parental (A, B and R) lines, only IR62829A revealed single off-type plants out of 25. The only hybrids confirming certification standards were Pant Sankar Dhan 1 (Syngenta), Pant Sankar Dhan 3 and Sahyadri. Study suggests use of appropriately chosen single microsatellite marker to estimate the genetic purity in hybrid rice. Correlation coefficient between GOT and DNA markers (0.89) highly significant and positive and suggests molecular techniques to substitute the conventional GOT which is more land, labour, money and time consuming.
Seeding sequence of parental lines of Pant Sankar Dhan 3 for multiplication of A line (A/B) and hybrid seed production (A/R) was determined using three methods of synchronization. In growth duration difference (GDD) method, B and R lines are earlier on an average of three planting dates by 5 and 4 days with respect to their seed parent. Effective accumulated temperature (EAT) for flowering of A, B and R lines are 1477.53, 1397.13 and 1421.66oC. Leaf number (LN) for flowering of A, B and R lines are 16.50, 14.96 and 15.30, respectively. For synchronization, seeding of B and R lines is suggested when the A line attains LN of 1.54 and 1.2, respectively for A/B and A/R production. Study revealed greater consistency in flowering days in CMS line with LND method, as compared to other two methods. It suggests LND method to be more reliable across the planting dates followed by EAT and GDD to predict synchronization between parental lines of hybrids.
Grow out test identified the hybrids as well as the traits with maximum percentage off-type plants. Flowering was to be most useful trait during selection/evaluation of a hybrid and genotype for genetic purity. DNA markers RM 154, RM 164, RM 234, RM 258 and RM 519 displayed polymorphism over all 13 lines and nine hybrids studied and suggested them as referral marker for authentication, purity estimation and protection of hybrids. Within 13 parental (A, B and R) lines, only IR62829A revealed single off-type plants out of 25. The only hybrids confirming certification standards were Pant Sankar Dhan 1 (Syngenta), Pant Sankar Dhan 3 and Sahyadri. Study suggests use of appropriately chosen single microsatellite marker to estimate the genetic purity in hybrid rice. Correlation coefficient between GOT and DNA markers (0.89) highly significant and positive and suggests molecular techniques to substitute the conventional GOT which is more land, labour, money and time consuming.
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