Critical Saline Concentration of Soil and Water for Rice Cultivation on a Reclaimed Saline Soil

Reclaimed tidal areas for rice cultivation are irrigated with salt mixed water when there is severe drought. Therefore, we identified the critical concentration of saline water for rice growth on a reclaimed saline soil in Korea. The experiment was conducted at the Kyehwado substation of the National Honam Agricultural Experiment Station (NHAES) during 2001-2002. Two experimental fields with 0.1-0.2% for low soil salinity and 0.3-0.4% for medium soil salinity levels were used. The experiment involved four levels of salt solution mixed with sea water (at 0.1, 0.3, 0.5, 0.7%) compared with a control using tap water in a split-plot design with three replicates. Saline solution was applied only two times at seedling stage (10 DAT and 25 DAT) for 5 days. Gyehwabyeo and dongjinbyeo, japonica rice varieties, were used in this experiment. Plant height and number of tillers sharply decreased in the 0.5% saline water in low soil salinity level and 0.1% in medium soil salinity level. For yield components, panicle number per unit area and percentage of ripened grain dramatically decreased in the 0.5% saline water in low soil salinity and 0.1% in medium soil salinity level. But 1,000-grain weight of brown rice decreased sharply in the 0.5% saline water in low soil salinity and 0.3% in medium soil salinity, indicating that this component was not much affected unlike other yield components. Milled rice yield decreased significantly with saline water level in both low and medium soil salinity. In the 0.7% low saline soil, the yield index was only 36% compared with the control. In medium soil salinity, even the control plot showed only 62% yield index compared with the control in the low soil salinity treatment. Results indicated that the critical concentration of saline water for rice growth in terms of economical income of rice production was 0.5% in low soil salinity and tap water in medium soil salinity.

간척지 벼 재배시 토양 및 관개수 염의 안전 한계농도

본 연구는 간척지 토양 염농도별(저염; 0.1-0.2%, 중염; 0.3~0.4%)로 분얼기 관개수 염수처리 농도에 따른 벼 생육 및 수량성을 검토하고자 시험한 결과를 요약하면 다음과 같다. 가. 토양 및 관개수 염농도가 높을수록 초장은 짧았고 주당경수도 적었으며, 특히 중염 토양에서 관개수 염농도 0.3% 이상에서는 모두 고사되었다. 나. 토양 및 관개수 염농도가 높을수록 출수는 지연되었으며, 토양 염농도간에는 중염 토양에서 저염 토양보다 2-5일 정도 늦었다. 다. 간장은 관개수 염농도가 높을수록 짧았고 중염 토양이 저염 토양보다 짧았으며. 수장도 같은 경향이었다. 라. 저염토양에서는 관개수 염농도가 높을수록 $\textrm{m}^2$ 당립수가 적고 등숙비율이 낮아, 쌀수량은 민물 관개 수량에 비해 관개수 0.l%는 92%, 0.3%는 84%, 0.5%는 56%, 0.7%는 36% 수준이었다. 중염토양의 쌀수량은 저염토양 민물 관개 수량에 비해 민물 관개는 62%, 0.1% 관개수에서는 30% 수준이었다. 따라서 관개수 염농도가 저염 토양은 0.7%, 중염 토양은 0.3%까지 생육은 가능하나 수량 감소가 커서, 소득지수로 볼때 간척지 쌀 생산 한계 관개수 염농도는 저염 토양은 0.5% 이하에서, 중염 토양은 민물 관개수에서 가능하였다.