Abstract
This experiment was conducted to find the effects of a $GA_3$ and thidiazuron (TDZ) on seedless rate, harvest time, fruit cracking and fruit quality in 'Kyoho' grapes over two years from 2008 to 2009. In 2008, fruit clusters were dip treated with $GA_3$ $25.0mg{\cdot}L^{-1}$ twice at full bloom (FB) and 14 days after full bloom (DAFB) in a combination with TDZ 0 or $2.5mg{\cdot}L^{-1}$. Berry seedless rate and berry enlargement were slightly improved only when TDZ was added to the second $GA_3$ treatment at 14 DAFB, compared to $GA_3$ + TDZ treatments at both FB and 14 DAFB. However, berry cracking rate was significantly increased by any plant growth regulator (PGR) treatments compared to non treatment. In 2009, $GA_3$ at $12.5mg{\cdot}L^{-1}$ and $25.0mg{\cdot}L^{-1}$ was dip treated twice at FB and 14 DAFB while TDZ $2.5mg{\cdot}L^{-1}$ was treated only at 14 DAFB. Berry cracking rate was depended on the concentration of $GA_3$ applied. The higher concentration at $25.0mg{\cdot}L^{-1}$ significantly increased berry cracking rate while the lower concentration at $12.5mg{\cdot}L^{-1}$ had no effect. Also, the addition of TDZ to $GA_3$ $25.0mg{\cdot}L^{-1}$ at 14 DAFB, substantially decreased the cracking rate to the level of untreated control. Although all PGR treatments advanced fruit maturity, the most significant advance occurred when TDZ was added to $GA_3$ $12.5mg{\cdot}L^{-1}$ only at the second dip. Considering the overall aspects related to fruit maturity and quality, we concluded that the double applications of $12.5mg{\cdot}L^{-1}$ $GA_3$ at FB and 14 DAFB with addition of $2.5mg{\cdot}L^{-1}$ TDZ only at 14 DAFB was appropriate to produce about 400-500 g size of seedless 'Kyoho' grape cluster having 35-40 berries.
본 실험은 $GA_3$와 thidiazuron(TDZ)이 '거봉' 포도의 무핵과율, 수확시기, 열과 및 과실품질에 미치는 영향을 알아보고자 2008년에서 2009년까지 2년간 수행되었다. 2008년에는 $GA_3$ $25.0mg{\cdot}L^{-1}$에 TDZ $2.5mg{\cdot}L^{-1}$를 혼용한 것과 혼용하지 않은 것을 만개기와 만개 후 14일에 침지 처리하였다. 과실의 무핵과율과 과실비대는 $GA_3$ $25.0mg{\cdot}L^{-1}$에 TDZ $2.5mg{\cdot}L^{-1}$를 2차에만 혼용처리 한 경우 TDZ를 1, 2차 모두 혼용처리한 것에 비하여 약간 증가하였다. 반면에 열과발생률은 모든 생장조절제 처리에서 무처리구에 비해 높게 조사되었다. 2009년에는 $GA_3$ $12.5mg{\cdot}L^{-1}$과 $GA_3$ $25.0mg{\cdot}L^{-1}$를 만개기와 만개 후 14일에 두 번 침지 처리하였으며 TDZ $2.5mg{\cdot}L^{-1}$를 만개 후 14일에만 혼용 처리하였다. 열과발생율은 $GA_3$의 농도에 영향을 받았다. $GA_3$ $25.0mg{\cdot}L^{-1}$의 고농도에서는 열과발생율이 유의하게 증가하였으나 $GA_3$ 농도를 $12.5mg{\cdot}L^{-1}$으로 낮출 경우 열과발생율에 영향이 없었다. 또한 $GA_3$ $25.0mg{\cdot}L^{-1}$ 처리 시에도 만개 14일 후 2차 처리 시 TDZ를 혼용할 경우 열과발생율이 무처리 수준까지 감소하였다. 모든 생장조절제 처리는 과일의 숙기를 촉진하였으며, $GA_3$ $12.5mg{\cdot}L^{-1}$에 2차에만 TDZ를 추가하였을 경우 가장 효과가 좋았다. 따라서 과실의 숙기와 품종 등 모든 관점을 고려하였을 때 35-40개의 과립수를 가진 400-500g 정도의 '거봉' 무핵과를 생산하기 위해서는 $GA_3$ $12.5mg{\cdot}L^{-1}$을 만개기와 만개 후 14일에 처리하며 TDZ를 만개 후 14일에만 혼용 처리하는 것이 가장 좋은 결과를 얻을 수 있는 것으로 조사되었다.
