Adaptation to flooding during emergence and seedling growth in rice and weeds, and implications for crop establishment.

Background And Aims: Direct seeding of rice is being adopted in rainfed and irrigated lowland ecosystems because it reduces labour costs in addition to other benefits. However, early flooding due to uneven fields or rainfall slows down seed germination and hinders crop establishment. Conversely, early flooding helps suppress weeds and reduces the costs of manual weeding and/or dependence on herbicides; however, numerous weed species are adapted to lowlands and present challenges for the use of flooding to control weeds.

Seed pre-treatment in rice reduces damage, enhances carbohydrate mobilization and improves emergence and seedling establishment under flooded conditions.

Background And Aims: Early flooding helps control weeds but reduces seedling establishment in direct-seeded rice (Oryza sativa). When combined with appropriate management practices, the use of genotypes that better tolerate flooding during emergence can enhance crop establishment in flood-prone areas. Management options include seed pre-treatment and we tested the influence of pre-soaking for 24 h prior to sowing or of priming (soaking for 24 or 48 h followed by drying).

Mechanisms associated with tolerance to flooding during germination and early seedling growth in rice (Oryza sativa).

Background And Aims: Flooding slows seed germination, imposes fatalities and delays seedling establishment in direct-seeded rice. This study describes responses of contrasting rice genotypes subjected to flooding or low oxygen stress during germination and discusses the basis of tolerance shown by certain cultivars.

Methods: In one set of experiments, dry seeds were sown in soil and either watered normally or flooded with 10 cm of water.

Blocking ethylene perception enhances flooding tolerance in rice seedlings.

Large areas of rainfed lowlands in South and Southeast Asia annually experience short durations of flash flooding during the rice-growing season, which dramatically affect plant survival and productivity. Submergence-intolerant cultivars usually show progressive leaf chlorosis, which could be triggered by ethylene produced during submergence. An ethylene inhibitor, 1-methyl cyclopropene (MCP), was used to evaluate the effect of ethylene on chlorophyll degradation and plant survival.