Weed diversity in two rice cropping systems in Indonesia

摘要

The objectives of this study was to find out weed diversity and weed dominance in two different rice cropping systems in Bandung, Sumedang and Tasikmalaya regency from November 2018 until February 2019. This research was conducted using the survey method with two rice planting systems, SRI and conventional systems. Five locations, were selected for each SRI and conventional system at similar altitude in each district. At each sample location, we carried out vegetation analysis five times for each area of rice field using the quadratic method. Weed sampling was done randomly by placing a 0.5 m x 0.5 m quadrat at five locations for each district and each rice cropping system. Absolute and relative weed densities, frequencies and dominance of each weedtype were recorded to compute sum dominance ratio (SDR), community coefficient (CC) and weed diversity (H). Destructive method was used to compute weed dominance. All above ground weed vegetations were harvested and separated by weed type and dried in an oven at 80°C for 48 h and their dry weight was recorded. The results showed that the dominant weeds on SRI were Cyperus difformis, Alternanthera philoxeroides and Ludwigia octovalvis, whereas in conventional rice cropping systems were Alternanthera philoxeroides and Pistia stratiotes. The species diversity index (H’) at SRI cropping systems in three research areas all belonged to medium category (H’<23), whereas at the conventional cropping system all research areas had low category of H’ <2. Community coefficient values at SRI and conventional cropping systems in three research areas were between 18.84 and 41.78 and belonged to the category of unacceptable, whereas the similarity of weed community between SRI and conventional cropping system inSumedang was fair, Bandung was poor and Tasikmalaya regency was very poor.