EVALUATION OF RICE STRAW YIELD, FIBRE COMPOSITION AND COLLECTION UNDER MEDITERRANEAN CONDITIONS

Rice straw remains almost unutilised in the majority of cases and is usually burned. Data on rice residue production under European conditions are extremely limited. A detailed assessment of rice biomass yield, partitioning and straw collection was carried out in Spain. Eleven commercial rice varieties were evaluated in 2015, and two baling trials were performed in 2014 and 2015. The average straw yield was 9.7 t.ha(-1). Straw yield, biomass partitioning indices and fibre composition varied significantly according to rice variety. Straw to grain ratio and harvest index were 1.00 and 0.50 on average for rough grain, and 1.25 and 0.41 for husked grain. Biomass partitioning indices significantly correlated with grain yield. Mean content of cellulose, hemicellulose, lignin and ash of rice straw was 32.5%, 19.8%, 6.5% and 13.7%, respectively. Straw amount of less than 3.0 t.ha(-1) can be collected during the baling trials. Rice straw could represent an eco-friendly source of lignocellulosic biomass in Europe, however, in order to achieve this, baling machine improvements and special crop management should be carried out.