There are considerable areas of wet paddy fields in Korea that requires improvement of its drainage system. In poorly drained sloping paddy fields, upland crops can be damaged by either rainfall or capillary rise of the water table caused by percolating water beneath the upper fields during summertime rainy season. The purpose of this study is to evaluate excess water stress of soybean yield by drainage systems.

Seed size has been considered as an effective criteria for selection of the most vigorous seeds in sorghum [(Sorghum bicolor (L) Moench]. The smaller seeds were inferior to the larger sizes in emergence and grain yield. This study was conducted to determine germination rate, field emergence and vigor of sorghum for selection of high quality seed by different seed size. Sorghum cultivar of two (Hwanggeumchal and Tojong) were separated into five seed size proportion (<2.36, 2.80, 3.15, 3.35 and >3.55 mm diam.) according to seed size. The larger seed was more higher 1,000 seeds weight, seed density, carbohydrates and protein content. Total seed germination performing varied 92% at the largest size (>3.55 mm diam.) frequently inferior to slightly 67% at smaller seed (2.36 to 2.80 mm diam.) in the standard germination test. Seed size did have a significant effect on mean emergence time (MET) and maximum emergence rate index (ERI) and percentage of emergence. It should be noted that the results refer to MET of sorghum seeds ranging from 4.26 to 4.74 days. The relationship of seed size was not only to stand establishment but to grain yield. Yield was most affected by seed size and large seeds were superior to the smaller seed in 25∼37% of the cases. Especially, yield was significant under 3.15 mm the beginning.

The objective of this study was to investigate the effect of drip irrigation level on soil salinity and growth of broccoli (Brassica oleracea L. var. italica) at the 'Saemangeum Reclaimed Tidal Land' from April to June, 2015. Drip irrigation was conducted at 1.5, 3.0 and 6.0mm•day -1 level for reduction of resalinization in the plastic vinyl house using 10cm spacing drip irrigation tape. At harvesting stage, the average EC of surface soil was 10.9dS•m -1 for 1.5mm•day -1 , 11.5dS•m -1 for 3.0mm•day -1 and 5.1dS•m -1 for 6.0mm•day -1 and was significantly reduced by 52~56% in 6.0mm•day -1 treated plot compared to those in 1.5 and 3.0mm•day -1 plots. The fresh bud weights of 1.5, 3.0 and 6.0mm•day -1 treatment plots were 60.9, 129.1 and 371.3g•plant -1 , respectively. The estimated soil EC for 50% yield reduction was 7.6dS•m -1 and the desalinization depth by drip irrigation was 30~40cm in soil profile. The total amount of drip irrigation water was estimated to be 422mm and the daily drip irrigation level was 6.0mm•day -1 for the prevention of resalinization during the broccoli growing period at the 'Saemangeum Reclaimed Tidal Land'. Our results suggested that drip irrigation shows effectiveness on the lowering the soil salinity according to the drip irrigation quantity but it needs more research on this study because dynamics of salts in soil can vary with many factors such as soil physico-chemical properties and seasonal climate.

1996). 그동안 논의 배수개선 연구는 주로 배수 불량지 및 저습답 개량, 간척지 제염의 한 방법 Joo, 1976;Joo, 1978;Kwun et al., 1980;Lee et al., 2001;Han et al., 1970)

Weed control is of fundamental importance when planting cereal crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Field experiment was conducted to evaluate the effect