온도ㆍ일장 2차원 Non-Parametric 모형에 의한 건답직파재배 벼의 출아기 예측

이변우 한국작물학회 1991 Korean journal of crop science Vol.36 No.2

온도와 일장을 예측변수로 하는 2차원 non-par-ametric model을 개발하여, 건답직파재배에서 파종기 이동 및 단일처리 (26개품종, 4월 10일부터 2주 간격으로 8회 파종, 해지기 직전 1시간 차광)를 하여 얻은 자료로부터 출아에서 출수까지의 일평균발육속도(DVR)를 추정하였다. 또한 여기서 추정한 DVR을 이용 독립자료에 대하여 모델을 검증하였다. 1. 발육 예측정도는 온도와 일장에 대한 smoothing parameter λ$_{T}$ 와 λ$_{L}$에 따라서 단조적으로 변하였으며 예측정도를 가장 높게하는 λ$_{T}$ 와 λ$_{L}$이 존재하였다. 2. 최적 λ$_{T}$와 λ$_{L}$은 품종에 따라서 달랐으며 5~100,000의 범위내에 있었다 3. 최적 λ$_{T}$와 λ$_{L}$에서 구한 DVR을 이용하여 발육을 예측하는 경우 C.V는 품종에 따라 0.5-2.6% 였으며 기존의 함수모델들 보다 예측 정도가 높았다 4. DVR을 계산하는데 이용되지 않은 독립자료를 이용하여 11개 품종을 대상으로 출수기를 예측한 결과 예측오차는 0-3일로 추정 정도가 높았다. Two dimensional non-parametric model using daily mean temperature and daylength as predictor variables was established and daily developmental rates (DVR) for the period of seedling emergence to heading were estimated for 26 rice cultivars by using data from field direct seeding dates and short-day treatments experiment carried out at experimental farm of Seoul National University in 1990. Three existing parametric models were tested for the comparision of predictability with non-parametric model. The non-parametric model was found to be superior to parametric models in predicting heading date. The developmetal indice(DVI) at heading date, cummulative DVR's from seedling emergence showed 0.5 to 2.2 percent of coefficient of variations. The non-parametric model revealed errors of 0 to three days in 11 varieties when applied to data independent of those used in estimating DVR.

벼의 Early Growth Vigor와 본답 생육과 관계

이변우 한국작물학회 2003 한국작물학회 학술발표대회 논문집 Vol.2003 No.-

지구가 점점 더워지고 있다 - 지구온난화는 먹거리 생산에 어떤 영향을 줄까

이변우 한국작물보호협회 1994 자연과 농업 Vol.15 No.4

벼 건답직파에서 LCU의 시비시기에 따른 생육 및 수량

이변우,김민호 한국작물학회 2001 한국작물학회 학술발표대회 논문집 Vol.2001 No.1

재생지를 이용한 벼와 감자의 멀칭 재배

이변우 서울대학교 농업생명과학대학 농업개발연구소 1998 농업생명과학연구 Vol.2 No.-

The farm products using less pesticide are increasingly preferred by the consumers in spite of high price and environmental concerns are rising because agrochemicals use is increasing steadily. Black plastic film mulch on various upland crops has been being used successfully for non-herbicidal culture of them as it inhibits weed emergence effectively, conserves soil moisture and raises soil temperature. However, plastic film hardly breaks down naturally in the soil, thereby, requiring much labor to remove it and causing environmental contamination. Biodegradable mulch paper was fabricated from recycled corrugate container and evaluated for its applicability to non-herbicidal rice and potato culture as an alternative to black plastic film. The mulch paper for paddy use is required to have considerable durability against microbial decomposition and wet tensile strength strong enough not to be broken through by weed for the effective weed control. We found that the paper mulching is very effective in controlling paddy weeds when mulch paper is sustained without decomposing completely until around maximum tillering stage at which rice canopy closes. The mulch paper was treated with polyamidepolyamine epichlorohydrin resin during fabrication to reinforce the wet tensile strength and to retard the decomposition. However, the mulch paper was not durable enough for effective weed control in conventional fertilizer management that nitrogen is splitted as basal, tillering and panicle fertilizer. As nitrogen topdressing at tillering stage accelerates the decomposition of mulch paper, another nitrogen management method omitting tillering fertilizer is required to secure the durability of mulch paper enough to control paddy weeds satisfactorily. The paper mulch on transplanted and dry-seeded rice cools the soil slightly, but shows yield performance not lower than the conventional rice culture with herbicidal weed control. The mulch paper shows much greater durability in upland field than in paddy field, ensuring the satisfactory upland weed control. Paper mulch on potato lowers soil temperature a little in early spring, but significantly in summer season that soil temperature is too high for normal potato growth. Paper mulch on spring- and fall-season potato crop shows much better yield performance than non-mulch and black plastic film mulch because paper mulch alleviates not only the soil moisture stress throughout growing season but also soil heat stress during summer season corresponding to tuber growth stage in spring culture and seedling growth stage in fall culture.

온실 재배 토마토의 증산모델 및 관개시기 진단법 개발

이변우 서울대학교 농업생명과학대학 농업개발연구소 1997 농업생명과학연구 Vol.1 No.-

건답직파재배에서 요소 비료 시용시 벼의 질소 이용과 손실

이변우 서울대학교 농업개발연구소 1999 농업생명과학연구 Vol.3 No.-

The objectives of this study were to evaluate the loss and recovery of urea nitrogen applied at sowing as basal nitrogen and topdressed shortly after flooding at four- to six-leaf stage of rice, and the effectiveness of nitrogen split application method, a nitrification inhibitor, DCD (dicyandiamide), and a slow release fertilizer, latex-coated urea(LCU) on the nitrogen economy and yield performance of rice sown directly on dry paddy field. Urea applied at seeding was lost almost completely during dry paddy period of 20 to 30 days before permanent flooding. Plant recovery of nitrogen applied at sowing was only 2.5 to 3.2% with 91 to 96% loss during dry paddy period until 4-leaf stage, showing little year to year variation. Nitrogen loss due to ammonia volatilization covered only 1 to 11%, and the rest substantial part of loss appeared to be due to leaching and denitrification. Both leaching and denitification were important mechanisms of nitrogen loss during dry paddy period before permanent flooding. Urea topdressed shortly after flooding at four-leaf stage was utilized 8 to 40% by plant with 15 to 50% loss within 10 days after fertilization, being much less in N loss compared to urea applied at sowing. Nitrogen topdressed at this stage was lost primarily due to leaching at very early stage of fertilization because of very high rate of water percolation. Ammonia volatilization loss was very low, accounting only for below 2% of applied nitrogen. The data suggested that urea fertilization at sowing as basal fertilizer should be avoided or reduced to a minimum amount and the nitrogen alloted to basal fertilizer in conventional dry-seeding rice culture rather be supplemented to the topdressing shortly after permanent flooding at four to six-leaf stage of rice for improving nitrogen fertilization efficiency and rice yield. DCD increased slightly the plant recovery of fertilizer nitrogend and rice yield. However, such a degree of improvement might be achieved by other means of fertilization practice without chemical.

질소시용량에 따른 다산벼와 화성벼의 광차단 및 이용효율 변화

이변우,최일선,김준한 한국작물학회 2000 한국작물학회 학술발표대회 논문집 Vol.2000 No.2

질소 농도가 다른 수도엽의 광합성 Modelling

이변우,명을재 한국작물학회 1993 한국작물학회 학술발표대회 논문집 Vol.1993 No.-

벼의 한계질소농도 결정 및 군락반사율을 이용한 질소영양상태 추정 연구

이변우 서울대학교 농업개발연구소 2000 농업생명과학연구 Vol.4 No.-

Critical nitrogen concentration(Nc) which is defined as the minimum nitrogen concentration to maintain the maximum growth rate at any time was investigated for rice plant. Based on Nc, nitrogen nutrition index(NNI) was calculated as its ratio to actual nitrogen concentration to examine the relationship with yield and yield components. In addition, investigated were the feasibilities to apply canopy reflectance measurements to diagnosing the nitrogen nutrition status nondestructively. Shoot critical nitrogen concentrations had no differences between rice varieties, Hwasungbyeo and Dasanbyeo, having the relationship with shoot dry weight(DW) as Nc=5.26DW-4.138(R2=0.966). This Nc dilution curve can be applied only in case that DW is greater than 1 to 1.5t/ha. For the early growth stage with DW less than 1 to 1.5t/ha, Nc should be determined with further detailed experiments. Nitrogen nutrition index(NNI), which is calculated as the ratio of Nc to actual N concentration, represented nitrogen nutrition status of rice very well. Showing the close relationship with rice yield and its components. Visible light reflectance had no great variations as LAI increases above 2. While near infra red(NIR) reflectance increased with LAI increase. Visible light reflectance decreased but NIR reflectance changed little with the increased nitrogen application levels. In cas of LAI less than 2, it was difficult to estimate canopy characteristics such as plant nitrogen concentration and NNI by canopy reflectance as the background reflectance of paddy soil and water contributed too much to canopy reflectance(ρ). Whereas, plant nitrogen concentration and NNI of rice canopy with LAI above 2 had very significant correlations with visible band reflectances, RVI, NDVI and so forth. Especially, RVIgreen(□) and NDVIgreen(□) showed the close linear regression relationship with NNI which had coefficients of determination of R2=0.802 and R2=0.845, respectively, indicating that these vegetation indexes could be used effectively to estimate NNI nondestructively. However, further studies to get rid of background effects on canopy reflectance are needed for the effective diagnosis of nitrogen nutrition status with canopy reflection measurements even in early growth stage with LAI below 2.