Istifadah N, Pratama N, Taqwim S, Sunarto T. 2018. Effects of bacterial endophytes from potato roots and tubers on potato cyst nematode (Globodera rostochiensis). Biodiversitas 19: 47-51. Bacterial endophytes are bacteria that inhabit plant tissues without causing any diseases. The endophytes existence may have negative, neutral, or positive effects on the host plants. This paper discusses the effects of bacterial endophytes isolated from potato roots and tubers on potato growth and their abilities to suppress potato cyst nematode, Globodera rostochiensis. The bacterial endophytes were isolated from roots and tubers of potatoes obtained from six plantation areas in West Java. The endophyte isolates were examined for their effects on potato growth. The non-pathogenic isolates were tested for their abilities to suppress G. rostochiensis in vitro and in potato plants. The results showed that from 88 bacterial endophyte isolates obtained, 13 isolates caused rot in potato seed pieces, 22 isolates inhibited the potato growth, while, 2 isolates increased the growth, and as many as 51 isolates did not influence the growth. The in vitro test using the isolate culture filtrate revealed that there were seven isolates that caused mortality of G. rostochiensis juvenile-2 by 67.5-97.7%. These isolates, however, were not effective in damaging the nematode eggs. In the greenhouse experiment, the bacterial endophyte isolates suppressed the number of cysts by 51.7-65.4% and that of the juvenile-2 of G. rostochiensis by 48.6-76.4%.

To fulfils the demand of melons (Cucumis melo), it requires intensive maintenance by agrochemical products. If this is done continuously, it will lead to soil degradation and disrupt the sustainable food supply. Therefore, an innovation is needed to maintain the sustainable food supply using biofilm biofertilizer technology. This study aims are to determine the potential of bacteria isolated from melon rhizosphere to solubilize phosphate and producing indole acetic acid (IAA) so that it can be developed into biofilm biofertilizer. Soil samples were taken from three melon gardens owned by farmers located in Sragen Regency, Karanganyar Regency and Wonogiri Regency, Central Java. In the laboratory, the soil bacteria then isolated from the soil using the dilution method. The isolates obtained then tested for their ability to solubilize phosphate and produce IAA. Phosphate is an essential nutrient for plant growth and IAA is plant growth promoting. The results showed that the highest phosphate solubilization potential was produced by bacterial isolate SRG 1A with a halo zone ratio of 1.957 and the highest concentration of IAA was produced by bacterial isolate WNG 1B with a value of 6.151 ppm. Based on the ability of the bacteria, indicates that the obtained bacterial isolates have the potential to be developed as a biofilm biofertilizer to help the growth of melon plants because it has the potency to solubilize soil nutrient and produce IAA.