INDONESIAN JOURNAL OF AGRICULTURAL SCIENCE

47-54

Authors: Eny Ida Riyanti, Edy Listanto, Alberta Dinar Ambarwati

Late blight caused by Phytophthora infestans is an important disease on potato. Several potato hybrids have been generated by crossing local varieties (Atlantic and Granola) with Katahdin SP951 which contains late blight resistance gene RB. Prior to release, these hybrids need to be evaluated for their environ-mental effects on non-target organisms and natural pests and diseases. The objectives of the study were to investigate the effect of LBR potato hybrids on beneficial soil microbes, pests and diseases. The trial was conducted in the confined field trial (CFT) in Lembang, West Java. The parental non-transgenic (NT) clones (Granola, Atlantic and Katahdin) and LBR hybrids (four clones of Atlantic x Katahdin SP951 hybrids; 10 clones of Granola x Katahdin SP951) were planted at a plant spacing of 30 cm x 70 cm. Fungicide applications were used as treat-ments (no spray, five and twenty times sprays). The experi-ment was arranged in a randomized completely block design with three replications. The parameters determined were popula-tions of N2 fixing and P solubilizing bacteria, soil C/N ratio as well as natural pests and diseases. The results showed that the transgenic LBR potato hybrids did not have negative effect on N fixing bacteria. The bacterial populations were around 1010-11 cells g-1 soil before planting, 1012 cells at 1.5 months after planting (MAP) and 108 cells after harvest. For P- solubilizing bacteria, their populations were 1010 cells before planting, 1012 cells at 1.5 MAP and 1011 cells g-1 soil after harvest. The soil C/N ratio of the transgenic plot was not statistically different compared to non-transgenic plot, i.e. 12-15 before planting, 10-11 at 1.5 MAP, and 10 after harvest in non-spray plot. Pests and diseases such as Alternaria solani, Liriomyza, potato tubber moth, aphid and mites on the transgenic and non-transgenic plots were statistically not different. The resistance score for A. solani was 7.2 (parental tansgenic) and 7.6 (parental non-transgenic); for Liriomyza it was 2.07 (parental transgenic) and 2.32 insect per plant (parental non-transgenic), the PTM was 0.63 (parental transgenic) and 0.73 insect per plant (parental non-transgenic), aphid and mites were 0.75 (parental transgenic) and 1.68 insects per plant (parental non-transgenic). The study indicated that LBR potato hybrids did not have any negative impacts on non-target organisms.

65-70

Authors: I Nyoman Widiarta, Adolf Bastian, Syahrir Pakki

Green leafhopper (GLH), Nephotettix virescens, is the most efficient vector of rice tungro virus disease. The disease is endemic in some provinces of Indonesia and commonly con-trolled using resistant varieties. Resistance of rice varieties to tungro could be classified into resistance to a virus and a vector. The history of GLH resistant varieties adoption affected the GLH adaptation in an area. The study was conducted in the period of 2009-2011 to evaluate the resistance status of five GLH resistant rice variety groups (T0-T4) using survival and transmission test. The GLH populations were collected from 15 tungro endemic provinces in Indonesia. The GLH was then reared in the greenhouse before used for the test. The degree of resistance to tungro viruses was calculated by adding the value of survival (weight x score of survival rate) and virus transmission rate (weight x score of transmission rate). The weights for survival and transmission rate were set to 40 and 60, respectively. The results showed that the rank of resistant variety groups in decreasing order of resistance were T4, T1, T2 and T3. Five variations in GLH transmission efficiency were identified, i.e. 170, 070, 050, 030 and 010. GLH populations from Bali and West Nusa Tenggara were the most efficient vector for rice tungro virus. We concluded that there were diversities in the degree of resistance among GLH resistant varieties. Variation in virus transmission efficiency (biotype) among GLH populations collected from various tungro endemic areas closely related to the history of adoption of rice varieties.

79-85

Authors: Siti Dewi Indrasari, Shinta Dewi Ardhiyanti, Buang Abdullah

Rice is an important source of vitamin B1 and folic acid, but cultivated rice cultivars contain low of these nutrient. Breeding program had been conducted and several advanced lines with a high vitamin B and folic acid contents were found. This research aimed to study the contents of vitamin B1 and folic acid in the brown rice and milled rice of fifteen promising lowland rice lines. Dried paddy (14% moisture content) were husked in the mini husker (Satake THU 35A) to obtain brown rice and milled rice by using abrasive-type mini polisher (Satake TM-05, 1,450 RPM for 2 minutes). Vitamin B1 and folic acid in the brown rice and milled rice were determined by using HPLC equipped with fluorescence detector for vitamin B1 and UV detector for folic acid. Four out of fifteen rice lines studied showed a unique characteristic of vitamin B1 content in the brown rice and milled rice. Rice lines which have highest vitamin B1 in the brown rice were B10267-4-PN-6-2-3-2-2-2-3-3-2 (3.03 mg 100 g-1), B10876H-MR-2 (2.13 mg 100 g-1), B10531E-KN-1-2-PN-1-4-2 (1.33 mg 100 g-1) and B12411E-RS*-1-2-1 (1.21 mg 100 g-1). However after milling, 43-92% of their vitamin B1 were lost; the least loss was observed in B12411E-RS*-1-2-1 (1.21 mg 100 g-1) which was only 4%. Three out of fifteen rice lines studied has highest folic acid in brown rice, i.e. BP400G-PN-12-3-6 (158.5 µg 100 g-1), B10876H-MR-2 (152.0 µg 100 g-1), and B11742-RS*-2-3-MR-5-5-1-Si-1-3 (100.0 µg 100 g-1). After milling the line B10876H-MR-2 had the highest folic acid content (52.0 µg 100 g-1), much higher than that of Ciherang variety as a control. This study indicates the importance of having a suitable milling instrument to minimize loss of vitamin B1 and folic acid. The study also suggests the importance of creating new rice cultivars that have high nutrient and resistant to milling process.