Differential carbohydrate metabolism occurs during submerged germination and early growth in barnyard grass (Echinochloa spp.) and contrasting rice (Oryza sativa L.) genotypes
2011
Estioko, L.P., Bicol Univ., Legazpi City, Albay (Philippines). | Baltazar, A.M. | Fajardo, N.N. | Laurena, A.C. | Merca, F.E., Philippines Univ.Los Baños, College,Laguna (Philippines) | Ismail, A.M. | Johnson, D.E., International Rice Research Inst., Los Baños, Laguna (Philippines).
With looming water crisis due to climate change, more rice farmers are likely to shift from transplanted to direct-seeded rice (DSR). An important aspect of DSR which is flooding to suppress weed growth, however, could also adversely affect growth of rice. This study was conducted to determine the morphological and biochemical responses of two rice genotypes IR42 and Khao Hlan On (KHO), and two grasses, E. crus-galli and E.colona to various times and depths of flooding. KHO and IR42 had less reductions in germination, shoot and root growth and tolerated early and deep flooding better than did E.crus-galli and E.colona. However, both weeds recovered fast, which allowed them to catch up with both rice genotypes after initial flooding injury. In all four species, flooding enhanced anaerobic fermentation through increased activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC). The ability of E.crus-galli and E.colona to shut off ADH and PDC after aerobic germination, which was not observed in both rice genotypes,could contribute to the faster growth and competitiveness of the two grasses. Activity of aldehyde dehydrogenase (ALDH), which detoxifies acetal dehyde, was higher in KHO and E. crus galli than in E.colona and IR42 under flooded conditions. Regulation of ALDH activity appeared to be implicated in the mechanisms of tolerance to flooding of E. crus-galli and KHO and may serve as basis in developing flood-tolerant rice cultivars and other crops.
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