Floating culture system (FCS) is the only feasible way for crop cultivation during high and prolonged flooding period at riparian wetlands. Objective of this research was to evaluate growth and yield of chili pepper cultivated using three different FCS during high flooding period at tropical riparian wetland. Floating rafts were constructed using used plastic bottles. Dimension of the raft was 2m x 1m with load capacity of 60 kg m-2 ; therefore each raft can carry 120 kg dead weight of growing media and chili pepper grown on it. Chili pepper used was CK9856 variety. Three FCS treatments applied were: P 1 , with gunny sack layer placed at interface between water surface and growing media; P 2 , without gunny sack at the interface; and P 3 , bottom part of growing media was immersed in water at 2-3 cm depth. These treatments were compared to P 0 , conventionally cultivated chili pepper as control. Result of this study revealed that chili pepper cultivated using FCS (P 1 , P 2 , and P 3) significantly outperformed those of conventionally cultivated (P 0) as indicated by higher growth and yield. Among FCS treatments, P 2 produced the highest marketable yield (248.9 g plant-1). Therefore, the P 2 is recommended for cultivation of chili pepper by smallholder farmers at riparian wetlands during high and prolonged flooding period.

Despite its large acreage, riparian wetland has been underutilized in Indonesia. Intensity of agricultural activities on this wetland was very low mainly due to two unfavorable extremes, i.e. unpredictable occurrence of flooding during rainy season and drought during dry season. Relevant, affordable, and acceptable technologies are required as solution to this problems. The technologies should be developed based on actual needs, preferences, and absorptive capacity of smallholder farmers, to ensure adoption. Objective of this study was to explore needs, preferences, and absorptive capacity of smallholder farmers through direct observation on their farming practices and dialogs on constraints in intensifying food production at riparian wetlands in Indonesia. The study was conducted at five villages in riparian wetland ecosystem in South Sumatera, Indonesia, from January to June 2016. This qualitative research was conducted in two stages: started with no-preconception Grounded Theory procedure; then, followed by questionnaire-guided survey. Results of this study indicated that intensive observation on farmer's practices and dialogs on constraints in intensifying food production could reveal needs, preferences, and absorptive capacity of smallholder farmers. Observed farmers' practices include land preparation and soil quality improvement, seedling preparation, transplanting, cropping management, and harvesting. Dialogs disclosed that unmanageable constraint but urgently needed by smallholder farmers in intensifying food production was technology solution for uncertain and uncontrollable natural flooding and drought occurrence at riparian wetlands. Government intervention is expected for constructing infrastructure for water management at riparian wetlands, i.e. polder system.

Besides unpredictable time and duration of flooding occurrence, low soil fertility has been another main agricultural issue at riparian wetland in Indonesia. The objective of this research was to determine the potential use of biochar in improving soil chemical properties, rice growth, and yields. Assessment on the effects of particle sizes (S) and application rates (R) of rice-husk biochar was executed through pot experiments in a greenhouse of Universitas Sriwijaya, Indonesia, from January to April 2017. The experiment was laid out in randomized block arrangement with three replications. S consisted of particle sizes ≤1 mm (S 1) and > 1 mm (S 2). R consisted of application rates at 1 t ha-1 (R 1), 2 t ha-1 (R 2), 3 t ha-1 (R 3), and 4 t ha-1 (R 4). Rice growth, yield, and growth analysis were measured during vegetative and generative stage. Soil chemical properties were analyzed after harvesting. Results indicated that application of biochar increased soil pH but did not affect cation exchange capacity (CEC), and availability of major soil nutrients. During vegetative stage, biochar application increased relative growth rate (RGR) and net assimilation rate (NAR) but decreased leaf are ratio (LAR). R 3 treatment significantly increased grain weight per panicle, number of filled spikelet, and weight of 1000 grains. Root and stem N content tended to be higher with biochar application. Application of biochar on riparian wetland soil exhibited some promising positive impacts on soil properties, growth, and yield of rice. However, a long term study on residual effects of biochar application in tropical riparian wetland needs to be pursued further for a more comprehensive understanding on this issue.

It was presumed that shallow water table restricted leaf growth and some water-related parameters; therefore, they can be used as indicators of plant stress due to the water table condition. Objective of this research was to evaluate morphological stress indicators in tomato plants exposed to shallow water table. The research was conducted in two stages: (1) developing reliable LA estimation model from June to September 2016; as pre-requisite for (2) calculating and evaluating the morphological indicators for stress due to shallow water table treatments, conducted from February to May 2017. Treated plants were placed inside experimental pools. Each treatment was done by partially submerging growing substrate to the targeted water tables at 5 cm and 10 cm below surface of the substrate. Untreated control plants were kept outside the pools. Zero-intercept linear model was the selected model for leaf area estimation after evaluating 15 combinations of five regression models and three predictors. Results of this study indicated that steady water table at 5-cm and 10-cm depth did not restrain relative leaf expansion rate (RLER) and there was no significant difference in specific leaf fresh weight (SLFW) and specific leaf water content (SLWC) between treated and untreated plants, measured prior to, during, and after recovery from shallow water table treatments. In conclusion, if position of water table was steady, the shallow water table at 5-cm depth or deeper did not affect tomato growth.

Leaf is a sensitive plant organ in responding to abiotic stresses, especially drought stress. Objective of this research was to evaluate changes of relative leaf expansion rate (RLER) and other leaf-related indicators as affected by gradual drought stress. The stress was induced by withholding water supply to chili pepper (Capsicum annum L.) for up to 12 days. Afterward, the crops were allowed to recover. The research was conducted in two stages. The first stage was for finding a reliable leaf area (LA) estimation model. The second stage was for evaluating relevance of RLER, specific leaf fresh weight (SLFW), specific leaf water content (SLWC), and total leaf area (TLA) as indicators for drought stress in chili pepper. Combinations of five regression models (linear, zero-intercept linear, quadratic, zero-intercept quadratic, and power) and three predictors, i.e. leaf length (L), leaf width (W), and LW were evaluated as candidates of LA estimation model. Selection of the models was based on coefficient of determination (R 2 ) and geometrical principles. The selected model was used for calculating RLER, SLFW, SLWC and TLA. Results of this study indicated that dynamic changes of RLER were mainly driven by daily day-night cycle rather than long-term gradual drought stress. SLFW and SLWC did not significantly decrease during drought stress period. However, drought stress significantly inhibited TLA in chili pepper. Chili pepper was able to recover from short-term (4 days) exposure to drought stress; yet, this crop was unable to recover after 8 days exposure to drought stress or longer.