자동 관개 시스템에서는 관수를 자동으로 개시하고 중지할 수 있는 기준값의 설정이 중요하다. 관수 기준값은 작물의 종류와 생육 시기, 토성, 용적 밀도 등에 따라 달라지는 포장 용수량의 토양 수분값으로 결정되기 때문에, 전문적인 지식과 분석 경험이 필요하여 현장 농업인이 직접 파악하는 것은 어렵다. 그래서 재배 작물의 명칭, 재배 지역 및 재배 토양의 토성 등을 조건 변수로 하여 적절한 토양 수분값을 데이터베이스로부터 추출하고, 작물의 종류 및 생육 시기별 토양수분 기준을 데이터베이스화하여 선택한 작물에 적합한 토양수분 장력값을 설정할 수 있는 알고리즘을 개발하였다. 이 알고리즘을 센서부, 제어부, 구동부로 구성되어 있는 시스템에 적용하여 토양 수분을 제어할 수 있는 시스템을 개발하였다. 실험구별로 수분 제어 기준값을 설정하여 측정한 수분값이 -33 kPa 실험구에서 부합률 97.3%, -25 kPa 실험구에서 부합률 96.6%의 결과를 나타내었다. 이 시스템을 이용하여 최근 농촌지역의 고령화와 노동인구 감소에 따른 생산성 감소를 억제하는데 기여할 것으로 사료된다.

Economic injury levels (EILs) and economic control threshold (ET) were estimated for the Tea red spider mite, Tetranychus kanzawai Kishida(Acari, Tetranychidae) in Rubus coreanus Miquel. T. kanzawai density increased until the early-July and thereafter decreased in all plots except the non-innoculation plot where initial density of the mite were different each 0，5, 10, 20 and 40 adults per plant branch on May 7 in 2008. And the occurrence of the densities were increased higher innoculated density than different innoculation density. The yield was decreased with increasing initial mite density and thereby the rates of yield loss was increased with increasing initial mite density. And T. kanzawai occurrence density, yields and the rates of yield loss, where initial density of the mite were different each 0,2, 5, 10 and 20 adults per plant branch on May 8 in 2009 were similar tendency to 2008 year results. The relationship between initial T. kanzawai densities and the yield losses was well described by a linear regression, Y = 0.6545X + 3.0425 (R<SUP>2</SUP> = 0.93) in 2008, Y = 0.9031X + 2.0899(R<SUP>2</SUP> = 0.96) in 2009. Based on the relationship, the number of adults per plant branch(EILs) which can cause 5% loss of yield was estimated to be approximately 3.0 in 2008 and 3.2 in 2009. And the ET was estimated to be approximately 2.4 in 2008 and 2.6 in 2009. The relationship between initial T. kanzawai densities and occurrence density of mid-May considering the best spray timing against T. kanzawai was well described by a linear regression, Y = 0.471X + 2.495(R<SUP>2</SUP> = 0.95) in 2008, Y = 0.9938X + 3.1858(R<SUP>2</SUP> 二 0.96) in 2009. Based on the relationship, the number of adults per Ieaf(ET) in mid-May which can cause 5% loss of yield was estimated to be approximately 3.6 in 2008 and 5.8 in 2009.

Cage experiments by artificial infestations with different initial densities of Frankliniella occidentalis were conducted to analyze damages and develop control thresholds of F. occidentalis on greenhouse eggplant in 2005 and on greenhouse sweet pepper in 2007. In the eggplant experiment, the infestations of F. occidentalis resulted in direct damage on fruit surface and non-marketable fruits which had several thin or thick lines or bleaching patches on the surface. F. occidentalis adults were frequently found on the flowers of eggplants, while nymphs were mainly observed on leaves. The fruit yield of eggplants was not significantly different among experimental plots with different initial density of F. occidentalis. Relationship between % non-marketable fruits among harvested fruits of eggplant and sticky trap catches of F. occidentalis (no. thrips/trap/week) at two weeks before the harvest showed a positive correlation. Using the estimated relationship, the control threshold of F. occidentalis on greenhouse eggplant was estimated at 10 adults per week at two weeks before the harvest when 5% of non-marketable fruit was applied for the gain threshold. In the experiment of sweet pepper, the direct damage by F. occidentalis was observed on the fruit surface and calyx, and the marketable grade of the damaged fruits decreased. The significant yield loss of marketable fruits was found in plots with high initial introduced-densities. There was a high relationship between thrips density and percentage of damaged fruits. Assuming 5% yield loss (non-marketable fruit) for the gain threshold, the control threshold of F. occidentalis on greenhouse sweet pepper was 4.8 adults per trap and 0.9 individuals per flower at two weeks before harvest.

This study aimed to estimate control thresholds (CTs) for imported cabbage worm, Artogeia rapae L., injuring chinese cabbage in the field. As a preliminary experiment, five level of densities of second instar larvae of A. rapae were inoculated on plant and checked injury rates under greenhouse condition. Average leaf area consumed for one week by a second larva was 657.7㎟ to the 3-WAT (week after transplanting) and 2495.8㎟ for two weeks to the 6-WAT, respectively. In field experiment, different larvae densities of A. rapae ranged from one to seven were inoculated on 20 plants. The percent yield reduction (Y) of chinese cabbage infested by different densities of A. rapae (X) for a three-week period were estimated by the following equation; (1) Y=1.764X-0.3049 (R2=0.9901) for the 3-WAT; and (2) Y=1.0305X-0.2976 (R2=0.9398) for the 6-WAT. Based on the relationships between the densities of A. rapae larvae and the yield index of chinese cabbage, the number of second instar larvae which caused 5% loss of yield (Gain threshold proposed by Japan), was estimated as 0.15 per plant for the 3-WAT and 0.26 for the 6-WAT.