<p>The study was aimed to determine the productivity and yield stability of ratoon rice genotypes in three environments and to obtain rice genotypes suistable for ratoonning on specific environment of tidal land. The experiment was designed in a randomized complete block with three replicates. Seedling was planted at 21 days old with spacing of 20 x 20 cm, one seedling per hill. Plants were harvested 30 days after heading by cutting at a height of 10 cm from the soil surface. One day after harvest, the land was irrigated as high as 3 cm and fertilized with Urea 50 kg/ha, TSP 30 kg/ha, and KCl 25 kg/ha. Yield stability was analyzed according to Eberhart and Russel (1966). Ratoons were sensitive to the environmental changes. Genotype IPB97-F-13-1-1, IPB 4S, and IPB 3S produced the main crop + ratoon grain yield of 5.26 t/ha, 5.14 t/ha, and 5.64 t/ha dry milling grain (DMG), respectively. Based on yield of the main crop + ratoon, IPB97-F-13-1-1 and IPB 4S was each considered as adaptable to the suboptimum condition (bi&lt;1). Ratoon crop yield of genotype IPB97-F-13-1-1, IPB 4S, and IPB 3S each was the highest in three locations. The ratoon crop contribution to the rice production was from 31.3% to 61.9% to the main crop.</p>

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Rice (Oryza sativa L.) is an important agricultural commodity in Indonesia. The combination of stability analysis on yields was considered accurate in selecting superior genotypes. The objectives of this study were as follows: identify the effects of genotypes, the environment, and their interactions (GEIs) on the yields of Fe-tolerant rice; select superior genotypes (stable and high yields) under diverse environment conditions in Indonesia; and determine the mega-environments (MEs) and representative environments for Fe-tolerant rice development. Fifteen genotypes of Fe-tolerant rice were used for this study. Field experiments were conducted at six experimental fields in Indonesia using a randomized block design with two replications. A combined analysis of variance (ANOVA) was used to determine the effect of genotypes, the environment, and their interactions on Fe-tolerant rice yields. Parametric, non-parametric, AMMI (additive main effects and multiplicative interaction), GGE biplot, and SI (sustainability index) measurements were used to determine the superior genotypes. GGE biplot was also used to determine MEs and representative environments. The measurement results showed that genotypes, the environment, and their interactions significantly affected rice yields with contributions of 13.30%, 35.78%, and 50.92%, respectively. One superior Fe-tolerant rice genotype (stable and high yield) was selected based on all measurements, namely G4 (B14316E-KA-4). In this experiment, two MEs were generated. Lampung was identified as a representative environment for the development of superior genotypes. The results of this study can be used as a consideration in the release and development of new superior varieties of Fe-tolerant rice in Indonesia.

Yield stability of rice varieties in diverse locations is an important aspect in a varietal recommendation to ensure better economic benefits for farmers. Multi-location trials in different locations or seasons will identify consistently high-performing varieties. This study aimed to test the yield stability of selected promising lines previously developed by means of Marker-assisted Breeding. Field trials were conducted in three different types of swampland locations: Lampung, South Kalimantan and Riau. The experiments were carried out in a randomized complete block design with three replications. A total of 15 selected rice lines were evaluated. Seedlings were transplanted to 2 m × 5 m plots with 20 cm × 20 cm planting distance. Yield stability was estimated using various analyses that measure coefficient of variability (Cvi), coefficient of regression (bi), deviation parameter (δ2), coefficient determination (Ri2) and AMMI biplot. Combined analysis of variance showed that line effect (G), environmental effect (E), and G × E interaction were statistically significant different. Using CVi25% and bi<1 threshold followed by AMMI biplot analyses, four lines (line number 1, 4, 6 and 11) were classified as having broad stability. Five lines (line number 5, 12, 13, 14 and 15) showed less yield stability but had better adaptation in tidal swamp environment. The other two lines (line number 3 and 7) showed a greater yield in the coastal swamp area, suggesting their potential as adapted lines suitable to this swampy environment.

The study of economic factors affecting sustainability of rice farming was conducted from January to September 2018 in Siak Regency. This study aimed to identify economic factors that affect the sustainability of rice farming in Siak Regency. The number of respondents in this study was 203 farmers, determined by a margin of error of 7% of the total population of agricultural households. The economic parameters observed in this study were the availability of farmersʼ capital, availability of production facilities, price of unhulled rice, agrotourism potential, economic efficiency, and farmersʼ income level. The results showed that the availability of farmers' capital (59.11%) was categorized as still lacking capital. Seed production facilities, fertilizers, and agricultural equipment are available following what is needed by farmers, except for the price of pesticides. The price of unhulled rice in Siak Regency is around Rp.4,500-Rp.4,700/kg, already above the Government Purchase Price of Rp.3,700-Rp.4,070/kg. Agrotourism objects that are becoming a trend and are currently in demand are a race using a tractor, a race to catch mice in the paddy fields before the rice is planted, a soccer match in the muddy fields after the fields are plowed and a competition to plant and harvest rice, both manually and using machines. Rice farming activities in Siak Regency are economically feasible to continue and profitable with 2.49-2.72Revenue Cost Ratio and 1.49-1.72 Benefit Cost Ratio.