竹笋截梢对绿竹生长及叶绿素荧光特性的影响

  目的  探讨绿竹Dendrocalamopsis oldhami矮化方法及矮化后绿竹生长规律及光合机制具有重要意义。  方法  以福建省尤溪县出笋盛期绿竹笋为研究对象，不截梢为对照（ck），比较不同高度H₁（60 cm）、H₂（90 cm）、H₃（120 cm）、H₄（150 cm）、H₅（180 cm）绿竹笋截梢对绿竹形态指标、成竹率、叶绿素质量分数及叶绿素荧光参数的影响。  结果  ① 竹笋截梢后绿竹形态发生显著变化，株高与截梢前绿竹笋高度呈线性极显著负相关（R2=0.90，P < 0.01），其中:H₅处理绿竹株高由对照的539.40 cm降低至234.70 cm，较对照降低了56.49%。随着绿竹株高降低，枝下高、节数及分枝率减少，主枝长度增加。竹笋截梢后绿竹成竹率为82.14%~85.71%，成竹率未达显著差异（P>0.05）。②竹笋截梢显著提高绿竹叶绿素a、叶绿素b及总叶绿素，降低了叶绿素a/b。③竹笋截梢处理初始荧光（F_o）与对照无显著差异。随着绿竹株高降低，PSⅡ最大光化学效率（F_v/F_m）和光化学猝灭系数（q_P）增加，而非光化学猝灭系数（q_NP）呈下降趋势。电子传递速率（E_TR）和PSⅡ实际光量子效率（Y_ield）增加，在H₅时达最大值，较对照分别提高了48.63%和42.17%。④Pearson相关性分析表明:绿竹株高与总叶绿素总量及叶绿素荧光参数F_v/F_m、Y_ield、E_TR显著负相关，与叶绿素a/b及q_NP显著正相关。  结论  绿竹笋高度H₅（180 cm）时截梢处理可有效控制高度生长，矮化后光化学功能进一步提高。

Effects of bamboo shoot truncation on growth and chlorophyll fluorescence characteristics of Dendrocalamopsis oldhami

  Objective  The aim is to explore the dwarf method and clarify preliminarily the growth and photosynthetic mechanism of Dendrocalamus oldhami, effects of bamboo shoot truncation on morphology, survival rate, chlorophyll content and chlorophyll fluorescence parameters of D. oldhami.  Method  Different heights H₁(60 cm), H₂(90 cm), H₃(120 cm), H₄(150 cm), H₅(180 cm) of bamboo shoots at peak period in Youxi County, Fujian Province were used as test materials and bamboo shoots without truncation as the control group.  Result  (1) Morphological characteristics changed significantly after bamboo shoot truncation treatment, and there was a significant negative correlation between plant height and bamboo shoot height before truncation (R2=0.90, P < 0.01). Plant height of H₅ after treatment was 539.40 cm and that of the control group was 234.70 cm, reducing by 56.49%. With bamboo shoot truncation treatment, the under branch height, internode number and branch rate decreased significantly while the length of the main branch increased. Survival rate of D. oldhami ranged from 82.14% to 85.71%, and no significant difference in survival rate was observed (P>0.05).(2) The chlorophyll a, chlorophyll b and total chlorophyll of D. oldhami increased while chlorophyll a/b decreased. (3) There was no significant difference in initial fluorescence (F_o) between the experiment groups and the control group. With the decrease of plant height, the PS Ⅱ maximal photochemical efficiency(F_v/F_m) and photochemical quenching coefficient (q_P) enhanced, while the nonphotochemical quenching coefficient (q_NP) reduced. The maximum values of electron transport rate (E_TR) and PS Ⅱ actual photochemical efficiency(Y_ield) were achieved under H₅ treatment, increasing by 48.63% and 42.17% respectively compared with the control group. (4) Pearson correlation analysis showed that plant height was negatively correlated with total chlorophyll and chlorophyll fluorescence parameters F_v/F_m, Y_ield and E_TR, and positively correlated with chlorophyll a/b and q_NP.  Conclusion  It could be concluded that 180 cm was the optimal bamboo shoot truncation treatment, which helped control plant height and improve photochemical effect.