ブドウの芽の休眠打破に及ぼす化学物質の種類と濃度の影響

　The effects of various chemicals and their concentrations on budbreak of ‘Pione’ grapevine (Vitis labrusca L. x V. vinifera L.) were studied by using single-bud cuttings obtained in endodormancy. When seven chemicals were applied to the upper half of cuttings, including bud, 2% hydrogen cyanamide (H2CN2) was most effective in budbreak, judging from acceleration and uniformity of budbreak. However, neither 10 % suspension of calcium cyanamide (CaCN2) nor 5% diallyl disulfide (C6H10S2) had any effect in breaking bud dormancy of ‘Pione’ cuttings. Budbreak in cuttings treated with 10 % hydrogen peroxide (H2O2) was inhibited slightly compared to the control cuttings. No effect of 2% potassium chlorate (KClO3), 2% sodium chlorate (NaClO3) or 2% paclobutrazol (PBZ) on breaking bud dormancy in ‘Pione’ cuttings was observed. The effects of CaCN2, H2CN2 and C6H10S2 on breaking bud dormancy in ‘Pione’ cuttings were compared at three to four concentrations. With CaCN2, a 20 % suspension significantly promoted budbreak, but a 5% suspension resulted in no effect. Both 5% and 2% of H2CN2 accelerated budbreak significantly and resulted in uniform budbreak, especially at 5 %, whereas at 0.5% H2CN2 no effect was observed. Of three concentration of C6H10S2, only a 10 % solution showed any effectiveness in budbreak. The results indicated that H2CN2 is most effective in breaking bud dormancy of ‘Pione’ grapevine cuttings, followed by CaCN2 and C6H10S2 in that order, although their effectiveness varied largely according to the concentrations for all chemicals.自発休眠期に採取したブドウ'ピオーネ'の挿し穂を用い，芽の休眠打破に及ぼす化学物資の種類と濃度の影響を調査した．７種類の化学物質について休眠打破の効果を比較したところ，発芽の促進と揃いからみて，２%シアナミド （H2CN2）の効果が最も大きかった．一方，10%石灰窒素（CaCN2）と５%２ 硫化ジアリル（C6H10S2）には休眠打破の効果は認められなかった．10%過酸化水素（H2O2）では発芽がやや抑制された．２%の塩素酸カリウ（KClO3）， 塩素酸ナトリウム（NaClO3）およびパクロブトラゾール（PBZ）はいずれも休眠打破の効果を示さなかった．石灰窒素，シアナミドおよび２硫化ジアリルの濃度を３～４段階に変え，'ピオーネ' 挿し穂の休眠打破に及ぼす影響を調査した．石灰窒素では，20%区の発芽が著しく促進されたが，５ｵ 区では発芽の揃いがよくなかった．シアナミドでは，５%区と２%区の休眠打破効果が著しかったのに対し，0.5%区では休眠打破の効果は認められなかった．２硫 化ジアリルでは，10%区で休眠打破効果がみられただけであった．以上の結果から，ブドウの芽の休眠打破に及ぼす化学物質の効果はシアナミドで最も大きく，次いで石灰窒素，２硫化ジアリルの順であったが，効果の程度は濃度によって異なった

休眠程度の異なるブドウ‘ピオーネ’の発芽に及ぼす温度の影響

The effects of temperature on budbreak of cuttings obtained at different stages of dormancy from 'Pione' grapevines (Vitis labrusca × V. vinifera) grown in open field were investigated. Cuttings were collected at monthly intervals from July to March. Judging from the number of days to initial and 60% budbreak after treatment, indicating promotion and the uniformity of budbreak, respectively, 30℃ was the most effective in budbreak, followed by 25 and 20℃ in that order in all treatment times. However, the effect of temperature on budbreak was markedly affected by treatment time. The number of days to initial budbreak (NDIB) increased gradually from July to October, peaked in December and thereafter decreased gradually towards March. The periods from July to September, from October to December, and from January to March were assumed to correspond to paradormancy, endodormancy, and ecodormancy of 'Pione' grapevines, respectively. Final percentage of budbreak was less than 100% until endodormancy for all temperatures. It was below 60% at 20℃ treatments of July to September. On the other hand, a uniform budbreak was observed in the treatments after the middle of endodormancy for all temperatures, resulting in almost 100% of final percentage of budbreak. There was a significant negative correlation between NDIB and cumulative chilling hour (CCH) of exposure to below 7.2℃ in the treatments after November, and also between NDIB and cumulative temperature (CT, ℃･h), a summation of temperature and hours of exposure to above 0°C from November 1 to each treatment time and hours of exposure to 20, 25, or 30℃ from start of treatment to budbreak in each plot. The results suggest that besides CCH, CT can also be used to estimate the completion of dormancy in 'Pione' grapevine bud.露地栽培されているブドウ‘ピオーネ’について，休眠の深さが異なる7月から翌年3月まで約1か月間隔で枝を採取し，1芽を有す挿し穂を調整した後，20，25および30℃に制御したインキュベーター（いずれも14時間日長）に入れ，経時的に発芽を調査した．発芽の早さを示す発芽所要日数と発芽の揃いを示す60%発芽所要日数から発芽に及ぼす温度の影響を評価した．実験期間中の温度を測定し，休眠完了と温度との関係を考察した．いずれの処理時期においても30℃の発芽が最も優れ，次いで25℃，20℃の順であった．しかし，発芽に及ぼす温度の影響は処理時期によって大きく異なった．すなわち，発芽所要日数は7月から10月までは徐々に増加し，11月に最大に達した後，3月に向けて少しずつ減少した．このことから，‘ピオーネ’では7月から9月が条件的休眠期，10月から12月が自発休眠期，1月から3月が他発休眠期と推察された．自発休眠期までの最終発芽率はいずれの温度も100%未満であり，また7月～9月の20℃処理では60%未満の発芽率であった．一方，自発休眠期の中期以降の処理ではいずれの温度とも均一な発芽を示し，最終発芽率はほぼ100%であった．11月以降の処理において，発芽所要日数と7.2℃以下の温度に遭遇した時間数（CCH）との間に有意な負の相関があった．また，11月１日から各処理時期までの0℃以上の温度に遭遇した時間数と20，25または30℃で処理を始めた日から各処理区の発芽までの時間数との積算（CT, ℃・h）との間にも有意な負の相関が認められた．以上のことから，‘ピオーネ’の芽の休眠完了の予測には低温遭遇量だけでなく，0℃以上の積算温度による方法も有効と考えられた

ブドウの芽の休眠打破に伴う生理的変化

Changes in CO2 and C2H4 production and water content of bud associated with breaking in ‘Pione’ grapevine (Vitis labrusca ×V. vinifera) were investigated throughout dormancy. Buds were collected monthly from August to December, during dormancy induction and maintenance, and CO2 and C2H4 production were determined by GC after incubation. Both CO2 and C2H4 production, especially for the latter, were low throughout the experiment. Water content of bud gradually increased until October ; thereafter it was constant. When CO2 and C2H4 production was determined from December to April, during dormancy maintenance to release, CO2 production was low from beginning of experiment to early April, prior to bursting, then rapidly increased to April 13, the bursting date. C2H4 production was almost undetectable throughout the experiment. Cuttings obtained at 3 different stages of dormancy were applied with 2% H2CN2 or distilled water (control), and budbreak was monitored in a plastic house kept at 20℃ or more. The CO2 and C2H4 production of bud were also determined weekly until budbreak. Regardless of treatment time H2CN2 significantly promoted budbreak compared to the control. Significantly higher production of CO2 was observed in cuttings treated with H2CN2 at 3 to 9 days before bursting for all the treatment times. C2H4 production was very low throughout the experiment for all the treatments. Irrespective of chemical application and treatment time, water content of bud decreased to the bursting stage, H2CN2 treatment especially showing a large decline. When dormant cuttings were treated with ACC, GSH (reduced glutathione) and GSSG (oxidized glutathione), only ACC promoted budbreak. Budbreak in cuttings treated with cyanamides such as CaCN2 and H2CN2 and cyanides such as KCN and NaCN was significantly accelerated except for H2CN2. Based on these results, the relationship between budbreak of grapevine buds and physiological changes in buds, and the roles of substances related to ethylene biosynthesis on breaking bud dormancy are discussed.ブドウ‘ピオーネ’について，休眠の導入と覚醒の過程における芽の生理的変化を調査した．休眠導入期の8月から覚醒初期の12月まで露地で栽培されている個体から芽を採取し，呼吸量，エチレン生成量および含水率を測定し た．調査期間を通して呼吸量は低く，エチレンもほとんど検出されなかった．芽の含水率は8月から10月まで僅かに上昇し，その後は変化がみられなかった．休眠覚醒初期の12月から発芽期の4月中旬まで，芽の呼吸量とエチレン生成量を測定した．呼吸量は4月上旬までは低く推移し，発芽（4月13日）の直前に急上昇した．エチレンは測定期間を通して低かった．休眠期の12月，1月および2月に採取した穂木を2% H2CN2 または蒸留水（対照）で処理し，25℃以上に保ったプラスチックハウスに入れて発芽を調査するとともに，経時的に芽の呼吸量，エチレン生成量および含水率を測定した．両時期とも対照区よりも H2CN2 処理区の発芽が早く，しかも休眠の深い12月処理で区による差が大きかった．両区いずれの時期とも，芽の呼吸量は発芽直前に急上昇したのに対し，エチレン生成量は調査期間を通して低いままであった．芽の含水率は，いずれの時期および処理区とも発芽期に低下し，特に H2CN2 処理区の低下が大きかった．休眠最深期の10月に採取した穂木に ACC，GSH（還元型グルタチオン）および GSSG（酸化型グルタチオン）を処理し，発芽に及ぼす影響を調査したところ，ACC だけが発芽を促進した．同様に，4種のシアン化合物（CaCN2，H2CN2，KCN，NaCN）を処理したところ，H2CN2を除き有意に発芽を促した．これらの結果を基に，ブドウの発芽と生理的変化との関係および休眠覚醒に及ぼすエチレン生合成関連物質の作用性について考察した

Estimation of Completion of Dormancy in Grapevine Bud Based on Cumulative Temperature

　This study was conducted to investigate the relationship between completion of dormancy of grapevine bud and temperature. Canes of ‘Kyoho’ and ‘Pione’ grapevines (Vitis labrusca×V. vinifera) grown in 7 vineyards with different temperature conditions, in Nagano, Northern Okayama, Yamanashi, Okayama, Okayama University, Fukuoka and Miyazaki, were collected at three different chilling exposures, December, January and February. These were then sent to Okayama University all at the same time. Cuttings with one bud were put into growth chambers kept at 25 or 30°C with 14 hours daylength, and budbreak in each cutting was surveyed at two day intervals for 60 days. Cumulative chilling hours (CCH) of exposure to below 7.2°C in each treatment time was largest in Nagano, followed in order by Northern Okayama, Yamanashi, Okayama, Okayama University, Fukuoka and Miyazaki. The CCH in Nagano was 2.5 to 4.8 times larger than in Miyazaki depending on the treatment time. The later the treatment time and the higher the temperature, the fewer were the number of days to first budbreak (NDFB) after treatment, irrespective of cultivar. A similar trend was observed in the number of days to 60% budbreak. In ‘Kyoho’ the NDFB was short in Nagano, Okayama University and Miyazaki, and longer in Okayama, Yamanashi and Fukuoka. In ‘Pione’ the NDFB was short in Fukuoka and Okayama University, and longer in Yamanashi and Okayama. The result was a weak negative correlation observed between CCH and NDFB in 4 of 7 vineyards. However, there was a strong positive correlation between NDFB and cumulative temperature (CT), a summation of temperature and hours of exposure to above 0°C from November 1 to treatment time and hours of exposure to 25 or 30°C from start of treatment to budbreak in each plot, in 6 vineyards excluding Miyazaki. The importance of estimating the completion of dormancy in grapevine bud based on CT is discussed.ブドウの芽の休眠完了と温度との関係を調査するため，温度条件の異なる７園（中信農試，山梨果試，岡山農試，岡山農試北部支場，岡山大学，福岡農試および宮崎）で栽培されている‘巨峰’と‘ピオーネ’から低温遭遇量の異なる３時期（12月，１月，２月）に結果母枝を採取した．直ちに岡山大学に送り，１芽を持つ挿し穂に調整した後，25または30℃のインキュベーター（14時間日長）に入れ，２日間隔で60日間発芽を調査した．処理開始時の7.2℃以下の遭遇量は中信農試で最も多く，次いで岡山農試北部支場，山梨果試，岡山農試，岡山大学，福岡農試，宮崎の順で，中信農試と宮崎では処理時期により2.5～4.8倍の差があった．発芽所要日数は，両品種とも処理時期が遅いほど，また温度が高いほど少なく，60％発芽所要日数もほぼ同様の傾向であった．‘巨峰’の発芽所用日数は中信農試，岡山大学および宮崎で少ない一方，岡山農試，山梨果試および福岡農試で多く，また‘ピオーネ’では福岡農試と岡山大学で少なく，山梨果試と岡山農試で多かった．７園のうち４園で低温遭遇量と発芽所要日数との間に負の相関がみられたが，相関係数は低かった．一方，11月以降処理開始までの０℃以上の温度の積算値と処理開始から発芽までの25または30℃での積算値を合計した積算温度と発芽所要日数との間には１園を除き極めて高い正の相関が認められた．これらの結果を基に，積算温度によるブドウの休眠完了予測の可能性を考察した