Physiological bases of heterosis and crop management strategies for hybrid rice in the tropics
2003
Peng, S. | Yang, J. | Laza, R.C. | Sanico, A.L. | Visperas, R.M. | Son, T.T.
Commercial production og three-line hybrid rice has expanded in some tropical Asian countries. Heterotic level, crop management, hybrid seed production, and grain quality are the major limiting factors for the further expansion of hybrid rice in this region. Traits responsible for heterosis for grain yield are different under different growing conditions. Under favorable growing conditions, the higher yield of hybrid rice is attributed to greater biomass production. Under suboptimum growing conditions such as low radiation, a higher harvest index contributes to the higher yield of hybrid rice. Greater leaf area production rather than tiller production is responsible for the higher biomass accumulation and grain yield of hybrid rice compared with the best conventional check variety in the tropics. A high tillering rate causes the early vigor of hybrid rice grown in temperate China. Hybrid rice technology is more profitable in rice-growing areas with medium and high yields (and#88055 t ha¯¹). Hybrid rice is suitable for both the dry and wet seasons. Both heterosis and yield differences are greater at a high N rate than at a low N rate. Hybrid rice needs a different N management strategy from conventional rice to maximize yield and minimize disease damage. Leaf area and tiller and biomass production of A lines do not limit the seed yield of hybrid rice. In fact, crop growth could be too high to cause a reduction in the outcrossing rate. Widening transplanting spacing up to 20 x 30 cm and transplanting split tillers are feasible ways to reduce the seed requirement to as low as 2.6 kg ha¯¹ without reducing grain yield.
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