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Rice cultivation in hills is challenged by sub-optimum weather conditions, low soil fertility, low temperature and moisture stress which impedes in attaining high productivity. To address this, four studies were carried out at ICAR Sikkim Centre, Gangtok, India to evaluate relative performance of local organic cultivars and conventionally bred varieties under an organic farming system. Conventionally bred varieties yielded significantly higher (45%) than local cultivars under recommended timely sown conditions whereas local cultivars showed superiority in grain yield under late sown conditions coinciding with low temperature during flowering to grain filling. Genotypes did not show significant interaction when organic or conventional production conditions were compared. For grain yield, there was a significant variation for variety × year interaction under organic system. Local organic cultivars had reduced grain yield and associated traits under rainfed upland conditions. Panicles per unit area had a significant positive association with grain yield in all production environments (organic lowland, organic upland, conventional lowland and conventional upland). Overall, the study indicates using local cultivars as donors for specific stress tolerance traits in background of high yielding genotypes to enhance rice yields sustainably under organic system in hills.
To explore trait variation, assess relative performance and establish association among yield and its associated traits in maize under organic system, 373 maize genotypes that consisted of landraces, open-pollinated varieties and single-cross hybrids were tested under organic management in Sikkim midhills. Data of 8 years (2009–2015 and 2019) for 12 agronomic traits viz., plant height, days to 50% tasselling, days to 50% silking, days to 75% dry husk, grain yield per ha, anthesis–silking interval, cob length, cob diameter, kernel rows per cob, kernels per row, number of cobs per plot and test weight were taken for analysis. Conventionally bred maize hybrids yielded 95.36% higher than the landraces and 58.60% higher than the open-pollinated varieties. Landraces displayed highest mean anthesis–silking interval of 7.18 days. In open-pollinated varieties, test weight showed a positive association with grain yield (0.37) while plant height (0.33) and kernels per row (0.34) were positively correlated to grain yield in case of landraces. Number of cobs per plot showed a very strong association with grain yield in hybrids (1.0). Kernels per cob and test weight contributed 24% to the variation in grain yield in open-pollinated varieties while anthesis–silking interval, days to maturity, number of cobs/plot, test weight and kernel per row accounted for 97% of the variation in grain yield in landraces. Grain yield in single-cross hybrids is contributed maximum (97%) by days to tasselling, silking, anthesis–silking interval, plant height and number of cobs per plot. The study indicates attaining high number of cobs per unit area along with emphasis on traits such as kernels per row, cob length and diameter for achieving higher yields in single-cross hybrids, selection of high test weight genotypes for open-pollinated varieties and emphasis on cob length, kernels per row and plant height for yield improvement in landraces.
‘Sikkim Primitive’ (SP) maize locally known as ‘murali makkai’ in Sikkim is a unique genetic resource exhibiting prolificacy and excellent popping capacity. Status of SP has reached extinction level due to its very small population size and neglected conservation efforts in-situ. In an initial effort to conserve and revive this landrace, characterization and documentation was carried out with 31 morphologically assayed traits recorded at different growth stages along with molecular characterization with simple-sequence repeat (SSR) markers. Plants exhibited prolificacy (5–6 cobs/plant) and excellent popping capacity along with other distinct traits. Plants were tall with thin stem, loose drooping tassel with anthocyanin coloration present at the base of glumes and in brace roots. Cobs were medium sized carrying small seeds with low test weight (87.90 g). A total of 22 SSR markers show amplification in murali makkai with markers bnlg1083, umc1353, umc1128, bnlg1017, bnlg2077, umc2298 and umc2373 amplified unique amplicons ranging from 100 to 800 bp. The characterized set of traits and molecular characterization for murali makkai will facilitate in utilization for genetic improvement and maintenance of genetic purity.
Maize and Imperata cylindrica have been utilized globally as a pollen source for induction of haploids in wheat through chromosome elimination technique. Pollen parents with a higher haploid induction rate are desired for recovering the high frequency of haploids in wheat and related species. The present investigation was carried out with the aim to assess haploid induction efficiency of diverse germplasm of maize and I. cylindrica in different generations of intra and intergeneric crosses of hexaploid and tetraploid wheat and triticale-wheat derivatives. Crosses of twenty-six lines (female) with each of two I. cylindrica and twenty-one maize genotypes (testers) were evaluated for four haploid induction parameters viz., pseudoseed formation frequency (PFF), embryo formation frequency (EFF), haploid regeneration frequency (HRF) and haploid formation frequency (HFF). I. cylindrica outperformed maize in haploid induction rate with a frequency of embryos formed with I. cylindrica (18.39%) were significantly higher as compared to maize (4.08%). In the case of I. cylindrica genotype Ic-ye identified best with mean EFF of 30.55, 14.48 and 25.43% for hexaploids, tetraploids and triticale × wheat derivatives, respectively whereas in the case of maize genotype HPMC-60 performed best with EFF of 12.61% for hexaploids, HPMC-58 (12.58%) for tetraploids and HPMC-16 for triticale × wheat derivatives with EFF of 8.91%. I. cylindrica genotype Ic-ye and maize genotypes HPMC-14, HPMC-53, HPMC-60, HPMC-64 with significantly positive GCA for haploid induction parameters may be utilized as efficient pollen parents for recovering higher frequency of haploids in wheat.
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