A study to determine the influence of soil water status on the physiology of rice plant Oryza sativa var. MR220 after panicle initiation stage was carried out at Ladang Merdeka Mulong Lating in the Kemubu Agricultural Development Authority (KADA) area, Kelantan. Five water management treatments imposed on direct seeded rice were; T1. Continuous flooding, T2. Early flooding up to panicle initiation stage followed by saturated (F55-saturated), T3. Early flooding for the first month followed by saturated (F-30 saturated), T4. Continuous saturated, and T5. Continuous field capacity condition throughout the growth stage. The treatments were arranged in Randomized Complete Block Design (RCBD) with four replicates. In-situ stomatal conductance measurement was carried out at 68 DAS (days after seeding) and the elemental analysis of soil and plant samples was carried out using the Instrumental Neutron Activation Analysis (INAA). Results from this study showed significant differences between treatments for soil moisture content and plant moisture content, but no significance different in leaf stomatal conductance. Rice plant moisture, soil moisture and leaf stomatal conductance showed no interaction. Early flooding up to panicle initiation stage followed by saturated (T2: F55-saturated) resulted in higher plant moisture content. Soil plant transfer coefficient was highest in continuous saturated (T4) for nitrogen, early flooding for the first month followed by saturated (T3: F-30 saturated) for potassium, continuous field capacity condition throughout the growth stage (T5) for magnesium, and continuous flooding (T1) for sodium.
Nowadays, in extreme changing environments, development of submergence tolerance variety is necessary for ensuring
crop production stability where, it is known that Malaysian commercial rice varieties such as MR219, MR220 and MR263
were severely susceptible to submergence. First step towards the development of submergence tolerance variety starts
with the breeding program by crossing MR263 and Swarna-Sub1. Marker-assisted selection (MAS) was carried out through
the utilization of simple sequence repeats (SSR) markers, considering its reliability as pre-selection tools to conduct this
research. F1
generations plants were confirmed by tightly linked markers. In case of background study, out of 180 SSR
markers, 38 were found polymorphic between two parents. Association of molecular markers and submergence tolerance
were determined using Chi-square test. MR263 × Swarna-Sub1 F2 lines were tested for Sub1 gene conformation using
the markers RM8300 and RM219. These markers showed a good fit to the expected marker segregation ratio (1:2:1) in
a Mendelian single gene model (DF=1.0, p≤0.05). Eleven homozygous lines with Sub1 gene out of 256 were selected
for future development of submergence tolerant varieties. Eleven lines were selected based on phenotypic study and
agronomic performance.