Effect of the Autumnal Cutting Times on the Regrowth , Accumulation of Carbohydrate and Dry Matter Yield of Italian ryegrass ( Loium multiflorum )

Italian ryegrass의 추계예취시기가 목초의 재생 , 탄수화물축적 및 건물수량에 미치는 영향

This experiment was carried out to study the effect of the autumnal cutting times on the regrowth, the accumulated carbohydrate and dry matter yield of Italian ryegrass The results were summarized as follows: 1. In dry matter yield, the plot of earlier cutting was shown the highest yield (p<0.05), and that of the last-cutting was shown lower yield of dry matter than that the none-cutting plot. 2. TSC (Total Water Soluble Carbohydrate) content slightly decreased after the first cutting and gradually increased according to the regrowth, and then decreased again to the second cutting time. And also the TSC content levels of stubble, stem and leaf at one week before falling to sub-zero temperature were all the highest in the eariler cutting plot (p<0.01), and there was significant correlation between the TSC content level and the second harvested dry matter yield (p<0.05). 3. CGR (Crop Growth Rate) was decreased below $8^{\circ}C$. RLGR (Relative Leaf area Growth Rate) and NAR (Net Assimilation Rate) were both high during 30 days after regrowth, and low after regrowth in all plots. LAI (Leaf Area Index) rapidly increased during 50 days after cutting, and then slowly increased in all the plots, and maximum LAI was 3.4-5.8. Also dry matter yield increased in the plots having a high LAI to 70 days after cutting. 4. It was recognized that there were significant correlation between TSC, LAI, CGR, NAR, LWR (Leaf Weight Ratio) and the second harvested dry matter yield during the low temperature periods, and the degree of contribution to dry matter yield was in order of LWR>LAI>TSC>NAR>CGR.

본(本) 시험(試驗)은 추파(秋播) 이탈리안라이그라스의 추계예취시취(秋季刈取時取)가 목초(牧草)의 재생(再生), 탄수화물축적(炭水化物蓄積) 및 건물수량(乾物收量)에 미치는 영향을 구명(究明)하기 위(爲)하여 포장시험(圃場試驗)을 수행(遂行)하였으며 결과(結果)를 요약(要約)하면 다음과 같다. 1. 건물수량(乾物收量)은 예취시기(刈取時期)가 빠른 구(區)일수록 높았고(P<0.05), 예취시기(刈取時期)가 제일 늦은 구(區)는 무예취구(無刈取區) 보다도 수량(收量)이 낮았다. 2. 건물중(乾物中) 전수용성탄수화물(全水溶性炭水化物)(TSC)의 함량(含量)은 일번예취직후(一番刈取直後)에 약간(若干) 떨어졌다가 재생장(再生長)에 따라 점점(漸漸) 높아졌으며 이번초(二番草) 예취기(刈取期)에 가까울수록 다시 떨어졌다. 기온(氣溫)이 영하(零下)로 하강(下降)하기 1주일전(週日前)의 TSC 함량수준(含量水準)은 그루터기, 줄기, 잎 별(別)로 모두 예취시기(刈取時期)간 빠른 구(區)일수록 고수준(高水準)이었으며 (P<0.01), 이번초(二番草)와 건물수량(乾物收量)과의 사이에 상관(相關)이 성립(成立)되었다(P<0.05) 3. 개체군(個體群) 생장속도(生長速度)(CGR)는 평균기온(平均氣溫)이 $8^{\circ}C$에서 하강(下降)할수록 떨어졌으며 상승(上昇)할수록 높았다. 상대엽면적생장율(相對葉面積生長率)(RLGR)과 순동화율(純同化率)(NAR)은 각구(各區) 모두 재생(再生)30일간(日間)이 가장 높았으며 재생후기(再生後期)에는 저하(低下)되었다. 엽면적지수(葉面積指數)(LAI)의 증대(增大)는 각구(各區) 모두 예취후(刈取後) 50일(日)까지는 빨랐으며 그 후(後)에는 완만하였고 최대치(最大値)의 범위(範圍)는 $3.4{\sim}5.8$이었다. 또한 예취후(刈取後) 70일(日)까지의 LAI가 큰 구(區)일수록 이번초(二番草)의 건물수량(乾物收量)이 높았다. 4. 생장(生長)이 억제(抑制)되는 저온기(低溫期)의 TSC, LAI ,CGR, NAR 및 LWR와 이번초건물수량(二番草乾物收量)과의 사이에 상관(相關)이 인정(認定)되엇으며, 그 공헌도(貢獻度)는 LWR>LAI>TSC>NAR>CGR의 순(順)이었다.