Browsing by Person "Johnson, Kristian Philip"

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Effects of salinity and alternate wetting and drying irrigation on genotypic performance of lowland rice in the Vietnamese Mekong Delta
(2023) Johnson, Kristian Philip; Asch, Folkard
Rice production in the Vietnamese Mekong Delta (VMD) is threatened by climate change. Predicted changes in the seasonal distribution of precipitation patterns along with higher temperatures increase the risk of severe drought during the winter-spring cropping season (the dry season). The resulting decrease in discharge of the Mekong River coupled with sea level rise, means sea water can intrude deep into the Mekong Delta during the dry season, such as during the dry season of 2016. Rice production is both victim and culprit, as it is a significant source of greenhouse gas (GHG) emissions, mainly methane (CH₄). The objective of my thesis was to show how rice production, from the level of plant to system, can become more resilient to drought and salinity, while also increasing its sustainability by reducing its emission of methane. The effect of the water saving irrigation technology, alternate wetting and drying (AWD), in combination with varieties commonly grown in VMD, was investigated in a two-year field experiment conducted during the dry season in the VMD. We measured water use, yield, yield components, phenology, as well as greenhouse gas emissions of methane and nitrous oxide (N₂O). Whereas the effect of salinity on growth of the same varieties from the field experiment was tested in a greenhouse experiment at the University of Hohenheim, Germany. We were able to show the efficacy of genotype selection and AWD in reducing methane emissions, mitigating the impact of severe dry seasons, and salinity intrusion in the VMD. Our findings could also be applied to other Asian Mega-Deltas.