Inoculation Effect of Methylobacterium suomiense on Growth of Red Pepper under Different Levels of Organic and Chemical Fertilizers

Use of plant growth promoting symbiotic and non-symbiotic free-living beneficial bacteria as external source of nitrogen is a major research concern for sustainable crop production in the $21^{st}$ century. In view of this, an experiment was conducted under controlled conditions to determine the effects of inoculation with Methylobacterium suomiense CBMB120, a plant growth promoting (PGP) root and shoot colonizer on red pepper, for the purpose of reducing external chemical nitrogen fertilization. Amendments with organic fertilizer and chemical fertilizer in the form of NPK were made at dosages of 50%, 75% and 100%, at 425 and $115kg/ha^{-1}$ measurements. The soil type used was loam, with a pH of 5.13. The growth responses were measured as plant height at 19, 36 and 166 days after transplantation and final biomass production after 166 days. It was found that inoculation with M. suomiense CBMB120 promotes plant height increase during the active growth phase at 19 and 36 days by 14.17% and 10.03%, respectively. Thereafter, the bacteria inoculated plantlets showed canopy size increment. A highly significant inoculation effect on plant height at p<0.01 level was found for 100% level of organic matter and chemical amendment in red pepper plantlets after 36 days and 19 days from transplantation. Furthermore, there was a significantly higher (10.30% and 6.84%) dry biomass accumulation in M. suomiense CBMB120 inoculated plants compared to un-inoculated ones. A 25% reduction in the application of chemical nitrogen can be inferred with inoculation of M. suomiense CBMB120 at with comparable results to that of 100% chemical fertilization alone. Enumeration of total bacteria in rhizosphere soil confirms that the introduced bacteria can multiply along ther hizosphere soil. Large scale field study may lead to the development of M. suomiense CBMB120 as an efficient biofertilizer.

화학비료와 유기질비료의 시용수준 및 Methylobacterium suomiense CBMB120의 처리가 고추 생육에 미치는 영향

화학비료와 유기질비료를 시비 수준 및 Methylobacterium suomiense CBMB120의 접종이 고추 생육에 미치는 영향을 확인하기 위하여 유기질비료와 화학비료의 시비량을 권장시용수준의 100%, 75% 및 50%로 처리하고 Methylobacterium suomiense CBMB120을 접종 한 후 정식 후 19, 36, 및 166일에 작물의 높이를 측정하였으며 이식 후 166일에 건물량 측정하였다. 균주를 접종한 처리구의 식물체 높이는 정식 후 19, 36일에 각각 14.17%, 10.03% 증가하였다. 건물 중 역시 10.30%, 6.84% 증가하여 유의성 있는 차이를 나타내었다. 또한 균주 접종은 유기질 비료 100% 시용구는 36일 후 고도의 유의성(p<0.01)을 갖는 차이를 보였으며 화학 비료 100% 시용구는 19일 후 고도의 유의성(p<0.01)을 갖는 차이를 나타내었다. 화학비료 100% 시용구에 균주를 접종하지 않은 처리 구와 화학비료 75% 시용구에 균주를 접종한 처리구의 생육을 분석한 결과 유의성 있는 차이가 없는 것으로 나타났다. 이는 향후 다양한 처리량 및 처리방법의 연구를 통하여 Methylobacterium suomiense CBMB120 균주의 접종이 화학비료를 일정 부분 감비 할 수 있다는 가능성을 시사한다.