86 research outputs found

    Agronomic Performance of F1 Hybrids of Rice (Oryza sativa L.) in Japonica-Indica Crosses

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    Generally F1 hybrids from crosses between japonica and indica rice show variable degrees of sterility. Previous studies revealed that among the indica rice, the Aus type has sexual affinity with japonica cultivars giving higher fertility in F1 hybrids. Therefore, we made an effort to obtain higher grain yield by producing F1 hybrids between japonica and Aus-type indica. A field experiment was conducted to investigate the heterosis in these F1 hybrids for dry matter accumulation, spikelet fertility, yield and yield attributes, to find cross combinations with higher grain yield, and examined the relationships of grain yield with some agronomic characters. F1 hybrids flowered earlier than their parent cultivars. Heterosis for dry matter accumulation was positive at the panicle initiation stage, at heading and at maturity. The average heterosis for number of panicles, grain and straw yield per plant, number of spikelets per panicle and 1000-grain weight was positive. A few F1 hybrids showed positive heterosis for number of filled grains per panicle, spikelet fertility and harvest index; but the average heterosis for these traits was negative. Among the yield components, a higher number of panicles per plant and higher number of spikelet per panicle contributed to higher grain yield in F1 hybrids. A significant and positive relationship existed between spikelet fertility and grain yield per plant. The higher grain yield was attributed to higher dry matter production rather than higher harvest index in F1 hybrids, although low spikelet fertility limited yield potential in some F1 hybrids

    Nursery Growth of Banana (Musa spp.) Plantlets Rooted on Auxin-free and Auxin-supplemented Media

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    This paper describes the effects of auxin added to the culture medium on main and branch root formation of banana (Musa spp.) shoots and growth characters of the plantlet rooted on the medium with and without auxin. Banana shoots cultured in vitro on Murashige and Skoog medium supplemented with 2 μM 1-naphthylacetic acid (NAA), rooted earlier and also had more adventitious roots than those cultured on the medium without NAA. However, the adventitious roots formed on the medium without NAA showed more lateral branching. Plant height and number of leaves per plantlet in in vitro culture were not influenced by the addition of NAA but under nursery conditions, plantlets rooted without NAA showed better growth in terms of days to the appearance of new leaf, plant height and number of leaves per plant. This might be due to the presence of abundant lateral roots. Even though auxins are generally known to promote rooting, NAA inhibited the formation of lateral roots in Banana plants
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