Improvement of seed health and yield of rice by seed coating application using volatile oils

Abstract

The aims of the research were (1) to determine the physiological and pathological quality of rice seed, (2) to obtain the most compatible coating formula with rice seed (3) to determine the effectiveness of seed coating against seed-borne pathogen and the effect of seed coating on seed viability and vigor during storage, (4) to determine the effect of seed coating on disease intensity, plant growth and yield, and quality of seed. The experiment was carried out in March 2012 in Seed Science and Technology Laboratory, Bogor Agricultural University and Seed Health Laboratory BBPPMB-TPH. Two varieties of rice seed were used, cv. Ciherang was obtained from PT. Sang Hyang Seri and HIPA 8 was obtained from BB PADI. The research consisted of four experiments. Experiment I, evaluation of physiological and pathological quality of rice seed cv. Ciherang and HIPA 8. Physiological quality test conducted using between paper method, pathological quality test conducted using blotter test and liquid assay method. The results showed that seeds of cv. Ciherang had 95% vigor index, 98% germination, 20.7% normal seedling etmal-1 speed of germination, 0.15 g normal seedling dry weight, and seedling growth rate 6.31 mg/normal seedling. Seed of cv. HIPA 8 had 49% vigor index, 77.3% germination, 8.3% normal seedling etmal-1 speed of germination, 0.10 g normal seedling dry weight, and 6 mg/normal seedling seedling growth rate. The result of seed pathological quality test showed Alternaria sp., Fusarium sp., Drechslera sp., Curvularia sp., Xanthomonas oryzae pv. oryzae and Erwinia sp. were found as seed-borne fungi and bacteria of rice seed cv. Ciherang. Alternaria sp., Fusarium sp., Penicillium sp., Curvularia sp., Cladosporium sp., X. oryzae pv. oryzae + X. campestris pv. oryzicola and Clavibacter sp. were found as seed-borne fungi and bacteria of rice seed cv. HIPA 8. Experiment II, evaluation of the effectiveness of binder material for rice seed coating using volatile oil. The objectives of this experiment were (a) to obtain the most compatible binder material and colorant (Ponceau 4R CI 16255) concentration with rice seed (Experiment IIa), and (b) to obtain the most compatible coating formula with rice seed (Experiment IIb). Experiment IIa consisted of three parts (1) test of arabic gum concentration 3%, 10%, 20%, 30%, 40% combined with colorant 0% and 0,1%; (2) test of carboxymethylcellulose concentration 1%, 3%, 5% combined with colorant 0% and 0,1%; (3) test of chitosan concentration 1%, 3%, 5% combined with colorant 0% and 0,1%. The experiment was done using factorial design with two factors and four replications. The results of experiment IIa showed that chitosan 1% and 3%; arabic gum 3%, 5% and 10%; CMC 1% were the most compatible binder concentrations with the rice seeds. Colorant material used was not toxic against rice seed. Experiment IIb was done using a completely randomized design with single factor and five replications. Factors of the experiment were coating formula consisting of binder materials with various concentrations according to the result of experiment IIa i.e. chitosan 1%, 3%; arabic gum 3%, 5%, 10%; and CMC 1% combined with three types of pesticides i.e. clove oil 1%, fragrant grass oil 2% and chemical pesticides (Benlox 0.2% + Agrept 0.2%), thus, experiment IIb consisted of 3 parts. Each part consisted of 6 levels. The results of experiment showed that the most compatible of coating formula with rice seed were clove oil 1% + chitosan 3%; fragrant grass oil 2% + carboxymethylcellulose 1%; and synthetic pesticide + arabic gum 10%. Experiment III, evaluation of effectiveness of seed coating using volatile oil against rice seed-borne pathogen and seed viability during storage. The experiment was conducted using completely randomized design with a single factor consisting of four levels: (1) clove oil 1% + chitosan 3%; (2) fragrant grass oil 2% + carboxymethylcellulose 1%; (3) synthetic pesticide (streptomycin sulphate 0.04% + benomyl 0.1%) + arabic gum 10%; and (4) control (without coating). In general, seed coating with clove oil 1% + chitosan 3% showed the strongest inhibitory effect against seed-borne fungi followed by fragrant grass oil 2% + CMC 1% and then synthetic pesticide + arabic gum 10%. Each coating formula prepared by dissolving the binder materials and pesticides according to treatments, colorant 0.1% and distilled water until the volume reached 100 ml. Arabic gum and CMC dissolved using distilled water. Chitosan was dissolved in 1% acetic acid solution. Then, 100 ml coating formula used for 500 g of seeds. Seeds were packed in a 0.8 mm polypropylene plastic and stored for 6 months at 27-30 °C and relative humidity of 71-78%. The result showed all treatments gave the same effect in controling seed-borne bacteria in both cultivars during storage. The result showed that all treatments gave no significant effect on seed viability but decreased vigor index of rice seed cv. Ciherang. All of coating formula decreased vigor indeks of rice seed cv. HIPA 8 and decreased seed viability except synthetic pesticide + arabic gum 10%. Experiment IV, evaluation of effectiveness of seed coating against seedborne pathogen, plant growth and seed production of rice in the greenhouse. The experiments were arranged in a completely randomized design with one factor (seed coating), the same as experiment 3. The result showed seed coating with clove oil 1% + chitosan 3% and fragrant grass oil 2% + carboxy methyl cellulose 1% reduced disease index in the greenhouse and decreased fungal and bacterial infections in seeds as compared to control. All treatments gave no significant effect on physiological quality of seed. Seed coating with clove oil 1% + chitosan 3% resulted the highest number of tillers, number of productive tillers, weight and number of full grains per clumps. In general, seed coating with clove oil 1% + chitosan 3% was the best treatment to control seed-borne pathogens of rice seed cv. Ciherang. All treatments were effective in reducing disease index in the greenhouse and produced more grain rice of cv. HIPA 8 than control. However, treatment of fragrant grass oil 2% + CMC 1% decreased percent of seedling emergence. In general, coating with clove oil 1% + chitosan 3% and chemical pesticide + arabic gum 10% were the best treatments for rice seed cv. HIPA 8.