Studi pengendalian keracunan besi pada padi di lahan pasang surut melalui keragaman genotipe padi dan ameliorasi lahan

Abstract

The experiments were conducted in the greenhouse of Bogor Agriculture University, from May to November 2010, and field experiment in the tidal swamp area, Barito Kuala regency, South Kalimantan, from February to November 2011. The objectives of the experiment were 1) to obtain the Fe concentration in the solution that causing iron toxicity symptom with criteria severe, moderate and slightly, 2) to obtain tolerant or rather tolerant (moderate) rice genotypes to Fe toxicity, 3) to study the mechanism of tolerance of rice genotypes to Fe toxicity, 4) to obtain the adaptive Salvinia sp. which have high biomass 5) to study the effect of rice genotypes, land amelioration and its combination to iron toxicity at two location and two cropping season in the tidal swamp land. Result of the first experiment which were conducted in the green house showed that after 4 weeks, iron toxicity symptoms of IR 64 variety can be grouped based on Fe concentration, i.e. slightly (skoring 3) = 52 ppm Fe, moderate (scoring = 5) = 143 ppm Fe and severe (scoring 9) is 325 ppm Fe. Iron toxicity symptoms of four genotypes (TOX4136, Inpara-1, Inpara-2, and Inpara-4) which have been selected at 325 ppm Fe concentration were lower in the field experiment. Inpara-1 and Inpara-4 genotypes more tolerant to Fe toxicity than other genotypes and had higher productivity at two experimental sites. The tolerant genotype retain more Fe on surface roots (plaque Fe) and had a ratio of Fe stems/leaves higher than the sensitive genotype. The ability of tolerant genotypes retain more Fe on the root surface (Fe plaque) indicated the existence of mechanisms of avoidance to iron toxicity in rice. Results of 10 Salvinia sp. accessions eveluation in nutrient solution with 7 ppm Fe concentration obtained 4 Salvinia sp. accessions had faster growth with doubling time of 6.0-8.6 days. Countinous testing of four accession of Salvinia sp. at soil of tidal swamp in a pot obtained one accession of Salvinia sp. from S. Kambat had growth and doubling time faster than other accession. Salvinia sp. accession from S. Kambat grown in the field showed growth and doubling time faster (5.1 days and 5.9 days) than which in the greenhouse at 7 ppm Fe in nutrient solution (7.5 days) and the soil of tidal swamp land in a pot (7.9 days). Land amelioration and tolerant genotypes can be control iron toxicity on rice and increased rice productivity in the tidal swamp area. Salvinia sp. which grown or composted had no different with composted rice straw and farmyard manure. The Belandean site had higher iron toxicity level and lower rice productivity than the Danda Jaya site. Iron toxicity can reduce grain yield in tidal swamp land 15.6-63.9% (scoring 2-7) compared to plant which grow normally (scoring 1). Level of iron toxicity at second cropping season lower than at first cropping season.