Upland rice response to phosphorus fertilization in Asia

George Thomas, Magbanua Rogelio, Roder Walter, Van Keer Koen, Trébuil Guy, Reoma Veronica. 2001. Upland rice response to phosphorus fertilization in Asia. Agronomy Journal, 93 (6) : 1362-1370.

https://doi.org/10.2134/agronj2001.1362

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Résumé : Upland rice (Oryza sativa L.) yields on infertile, acid soils in the Asian uplands average only 1 Mg ha-1. Phosphorus deficiency is considered a major soil constraint to increased yield, but little quantitative information is available. We analyzed P responses of traditional rice on farm in Laos, Thailand, and the Philippines and improved varieties in researcher-managed trials in the Philippines. Treatments in onfarm trials were a control and 50 kg P ha-1 ± 100 and 50 kg ha-1 N and K, respectively. Treatments in researcher-managed trials were P rates on an unlimed and limed Ultisol. Mehlich-1 extractable P correlated with on-farm grain yield (r = 0.47). Phosphorus fertilization increased average grain yield (1 Mg ha-1) by 20%, total biomass (4 Mg ha-1) by 27%, and P uptake (4.1 kg ha-) by 53%. Yield increased 37% with P + N + K, but only 16% of the 2.4 Mg ha-1 biomass increase was grain. Improved rice in researcher-managed trials responded to P, with a larger proportion of biomass partitioned to grain [i.e., higher harvest index (HI)]. Grain yield of 'UPLRi-5' increased from 3.2 to 4.6 Mg ha -1 in limed soil while that of 'IR55423-01' increased from 3.4 to 4.0 Mg ha-1 in unlimed soil. Phosphorus fertilization always increased the frequency of higher yields averaged across trials, soils, varieties, and growing conditions. Yield gain from onfarm P fertilization of traditional rice was small because of low HI, unlike in improved varieties, which had a HI. We infer that increasing upland rice yield in Asia would require genotypes with higher HI in addition to P fertilization.

Mots-clés Agrovoc : riz pluvial, Oryza sativa, phosphore, carence du sol, fertilisation, Acrisol, rendement des cultures

Mots-clés géographiques Agrovoc : République démocratique populaire lao, Thaïlande, Philippines

Mots-clés complémentaires : Ultisol

Classification Agris : F04 - Fertilisation
P35 - Fertilité du sol

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