수도품종들의 저온에 대한 생리생태적 반응특성을 구명하여 내냉성 품종육성과 냉해를 경감 수 있는 재배법개선기술을 확립하고저 1975년부터 1980년에 걸처서, 유일형과 일본형 및 인도형 품종들을 공시하여 그들의 생육시기별 시비조건별 저온반응의 특성을 검토하기 위하여 저온처리를 작물시험장 인공기상실에서 그러고 저수온처리에 관한 시험을 작물시험장 춘천출장소 냉수시험지에서 수행한 바 그 결과를 요약하면 다음과 같다. 1. 15~circC 저온하에서 70% 이상의 실용적 발아율 얻을 수 있는 기간은 일본형품종들은 15~circC에서 10 일간, 통일형품종들은 15 일간이었다. 통일형품종들의 저온발아성 검정은 저온에서 장기간 실시하는 것 보다 16~circC에서 6일간 치상하는 것이 적당하였다. 2. 유묘의 저온저항성은 3.0～3.5 엽기묘가 가장 낮고 묘영이 진전됨에 따라 점차 높아켰으며 3엽기와 6엽기의 저온저항성간에 는 고도의 정상관을 보였다. 3. 주ㆍ야 15～10~circC온도에서는 일본형 및 통일형 품종 모두 42일 처리정도에서 식물체가 고사하고 20～15~circC에서는 일본형 품종은 분벽이 잘 이루어지나 통일형품종은 약관 억제되며 25～15~circC에서는 양품종군 모두 분벽이 촉진되었다. 그러나 초장신장 속도는 저온일 수록 저하되었다. 4. 이삭의 지경 및 영화분화는 출수전 30일부터 출수기까지 주ㆍ야 25～20~circC처리와 30～25~circC 처리시에는 모든 품종에서 잘 이루어졌으나 20～15~circC 처리구에서는 통일형품종은 지경 및 영화 분화수화수가 전자에 비하여 감소하였고 일본형품종은 큰 차이가 없었으나 이삭의 추출은 억제되었다. 5. 저기온에 의한 출종지연은 감수분열기에 저온처리한 것이 분얼최성기에 저온처리한 것 보다도 1～3일 이 지연되였으며 같은 시기에서는 저온처리 일수가 길수록 출수지연도가 컸다. 6. 벼 생육기간별로 17~circC냉수를 10일간 처리한 경우에 출수지연도는 분얼기 > 감수분열기 > 수잉기의 순이였고 품종별로는 수원26004 > 수원23005 > Lengkwang의 순이있다 냉수처리에 의한 출수지연도는 간장단축률 및 불임율과 유의한 정의 상관을 보였다. 7. 감수분열기의 저기온(15~circC)과 고기온(25~circC)처리는 고기온(25~circC)과 저기온(17~circC) 처리보다 간장단축율이 켰으며 이삭 추출도도 낮았고 장간종인 Lengkwang은 단간종인 수원26004에 비하여 저기온에서의 간장단축율이 낮은 경향이었다 이삭 추출도는 출수기에 저온처리를 하였을 때 가장 낮았으며 통일형품종은 일본형품종보다 이삭 추출도가 현저히 낮았고 저온에 의하여 간장단축도 심한 품종은 이삭 추출도도 매우 낮았으며 이들 간에는 고도의 유의한 정의 상관이 있었다. 8. 분벽기의 냉수처리는 수수를 증대시키고 감수분열기의 냉수처리는 수수를 감소시켰다. 생육시기별로 냉수처리시기가 빠를수록 간장단축율이 크고 이삭 추출도도 낮아졌다. 9. 감수분열기의 17~circC 저온처리에 의한 불임유발은 3일간 처리로서는 크게 나타나지 않으나 9 일간처리에서는 심하게 나타났으며 수원26004와 밀양4002가 저온처리에서 불임율이 가장 낮았다. 저온처리가 임실장해를 가장 크게 유발한 것은 출수전 15일부터 출수전 5일까지 사이의 처리였으며 일본형인 진흥은 통일형인 통일, 수원26004보다 임실장해가 현저히 적었다. 그러나 감수분열기의 저온처리에 의한 임실장해정도와 출수기의 저온처리에 의한 임실장해정도간에는 유의한 정의 상관을 보였으며 또한 저온에 의하여 이삭 추출도가 낮거나 간장단축율이 큰 품종은 임실율도 떨어지는 경향이었다. 10. 냉수처리에 의한 임실장해는 감수분열기처리(엽이간장-15～10cm)에서 가장 크고 품종별로는 수원26004, 조생통일 > 농백, Towada > 저온저항성이 강한 Lengkwang순이었다. 냉수처리시의 수심과 유수의 위치는 임실비율과 매우 밀접한 관계가 있으며 수심이 20～40cm로서 유수의 위치가 물속에 있면 수원26004는 불임율이 높았고 유수의 위치가 물위에 있었던 Lengkwang은 불임율이 낮았다. 11. 수전기에 3 일간 15~circC의 저온처리를 한 경우 등숙에 큰 영향이 없었으나 6 일간 처리한 경우에는 수원287호와 수원 26004만이 60% 이하의 임실율을 보였으며 9 일간 처리한 경우에는 모든 품종에서 임실율이 60 이하로 떨어겼다. 그러나 출수 10일 후부터 17~circC로 20일간 처리한 경우에는 등숙장해가 크지 않았다. 12. 질소, 인산, 가리, 칼슘, 마그네지움 및 아연등의 양분흡수는 19℃ ± 5보다 25℃ ± 5에서 흡수가 증대되었으나 망간은 반대로 평균 25~circC보다 19℃ 에서 흡수가 더욱 많았다. 13. 냉수답에서 질소, 인산, 규산 및 퇴비시용은 분벽 및 수수를 증가시키고 임실율을 향상시키며 수량을 증대시켰다.

Experiments were conducted to investigate rice varietal response to low water and air temperatures at different growth stages from 1975 to 1980 in a phytotron in Suweon and in a cold water nursery in Chooncheon. Germination ability, seedling growth, sterility of laspikelets, panicle exertion, discoloration of leaves, and delay of heading of recently developed indica/japonica cross(I/J), japonica, and indica varieties at low air temperature or cold water were compared to those at normal temperature or natural conditions. The results are summarized as follows: 1. Practically acceptable germination rate of 70% was obtained in 10 days after initiation of germination test at 15~circC for japonica varieties, but 15 days for IxJ varieties. Varietal differences in germination ability at suboptimal temperature was greatest at 16~circC for 6 days. 2. Cold injury of rice seedlings was most severe at the 3.0-and 3.5-leaf stage and it was reduced as growth stage advanced. A significant positive correlation was observed between cold injury at 3-leaf stage and 6-leaf stage. 3. At day/night temperatures of 15/10~circC seedlings of both japonica and I/J varieties were dead in 42 days. At 20/15~circC japonica varieties produced tillers actively, but tillering of I/J varieties was retarded a little. At 25/15~circC, both japonica and I/J varieties produced tillers most actively. Increase in plant height was proportional to the increase in all varieties. 4. In I/J varieties the number of differentiated panicle rachis branches and spikelets was reduced at a day-night temperature of 20-15~circC compared to 25-20 or 30-25~circC, but not in japonica varieties although panicle exertion was retarded at 20-15~circC. The number of spikelets was not correlated with the number of primary rachis branches, but positively correlated with that of secondary rachis branches. 5. Heading of rice varieties treated with 15~circC air temperature at meiotic stage was delayed compared to that at tillering stage by 1-3 days and heading was delayed as duration of low temperature treatment increased. 6. At cold water treatment of 17~circC from tillering to heading stage, heading of japonica, I/J, and cold tolerant indica varieties was delayed 2-6, 3-9, and 4-5 days, respectively, Growth stage sensitive to delay of heading delay at water treatment were tillering stage, meiotic stage, and booting tage in that order, delay of heading was greater in indica corssed japonica(Suweon 264), japonica(Suweon 235), and cold tolerant indica(Lengkwang) varieties in that order. Delay of heading due to cold water treatment was positively correlated with culm length reduction and spikelet sterility. 7. Elongation of culms and exertion of panicles of rice varieties treated with low air temperature 17~circC. Culm length reduction rate of tall varieties was lower than that of short statured varieties at low temperature. Panicle exertion was most severaly retarded with low temperature treatment at heading stage. Generally, retardation of panicle exertion of 1/1 varieties was more severe than that of japonica varieties at low temperature. There was a positive correlation between panicle exertion and culm length at low temperature. 8. The number of panicles was increased with cold water treatment at tillering stage, but reduced at meiotic stage. As time of cold water treatment was conducted at earlier growth stage, culm length was shorter and panicle exertion poorer. 9. Sterility of all rice varieties was negligible at 17~circC for three days but 30.3-85.2% of strility was observed for nine-day treatment at 17~circC. Among the tested varieties, sterility of Suweon 264 and Milyang 42 was highest and that of Suweon 290 and Suweon 287 was lowest. The most sensitive growth stage to low temperature induced sterility was from 15 to 5 days before heading. There was positive correlation between sterility of rice plants treated with low temperature at meiotic and heading stage. 10. Percentage of spikelet sterility was greatest at cold water treatment at meiotic stage (auricle distance -15～-10cm) and it was higher in 1/1 (Suweon 264, Joseng tongil), japonica (Nongbaek, Towada), and cold tolerance indica(Lengkwang) varieties in the order. Level of cold water and position of young-ear affected on the sterility of varieties at meiotic stage; percentage of spikelet sterility of variety, Lengkwang, of which young-ear was located above the cold water level was high, but that of short statured variety, Suweon 264, of which young-ear was located in the cold water was lower. 11. Percentage of ripened grains was not reducted at 15~circC air temperature for three days at full heading stage in all varieties. However, at six-day low temperature treatment Suweon 287, Suweon 264 showed percentage of ripended grains lower than 60%, but at nine-day low temperature treatment all varieties showed percentage of ripened grains lower than 60%. Low temperature treatment of 17~circC from 10 days after heading for 20 days did not affect on the ripening of all varieties. 12. Uptake of nitrogen, phosphorous, potassium, calcium, and magnesium in whole plants was higher at average air temperature of 25~circC, but concentration of the elements was lower compared to those at 19~circC. However, both total uptake and concentration of manganese were higher at 19~circC compared to 25~circC. 13. Higher application of nitrogen, phosphorus, silicate, and compost increased yield of rice due to increased number of panicles and spike let fertility in cold water irrigated paddy.

• 吳潤鎭(작물시험장) | 오윤진