Response Surface Analysis of Seed Germination Percentage and MTG of 6 Basil Cultivars

By Emily ZhouDepartment of HorticultureSTAT 5606 Spring 2013

Sweet Basil (Ocimum basilicum L.)o A frost sensitive low-growing herb

in family Lamiaceae (mint family)o A summer and annual crop in North

America and native to southern Asia

o Grows a lot in Mediterranean area and South Asia

o More than 60 cultivars

2

Seed Germination Testing Very important to assess quality

6 Sweet Basil Cultivars1. ‘Italian Large Leaf’ (‘ILL’): higher yields2. ‘Italian Large Leaf’ 35X (‘ILL’ 35X): 5+ years old

seeds3. ‘Nufar’: disease (Fusarium) resistant ‘Italian Large

Leaf’ type4. ‘Genovese’: traditional Italian basil5. ‘Genovese Compact Improved’ (‘GCI’): for

containers and pack sales6. ‘Aroma 2’: disease (Fusarium) resistant ‘Genovese’

type

Thermo-gradient Table Creating different temperatures at same time

using the principles of thermodynamics. Wide temperature range from -10 to 85ºC (1.1ºC )

. Often used to test seed germination.

Germination Testing 4 × 25 seeds of cultivar 1 and 2 at each

temperature 2 × 50 seeds of cultivar 3 to 6 at each

temperature Seeds were placed in 11×11×4 cm transparent

covered plastic boxes, on top of two thicknesses of germination blotter paper, the blotters were saturated with 15 ml distilled water

Standard AOSA (The Association of Official Seed Analysts) germination testing procedure, grow in dark in one dimensional thermo-gradient table

Germination Data Analysis Germination percentages

MTG (mean time to germination): ∑(NiTi)/∑(Ni), where Ni is the number of new germinated seeds at time Ti after imbibition calculated from four replications of 25 seeds each (Nerson and Paris, 1988)

Analysis of Covariance of Germination%

Analysis of Covariance of Germination%

Analysis of Covariance of Germination%

Response Surface

Germ% Response Surface Effect by Cultivar

Germ% Response Surface Effect by Cultivar

Cultivars Max Germ (%)

Optimal Temp (°C)

R2 P

1-ILL 35X 84.1 32.2 0.821 <0.0001*

2-Nufar 100 26.4 0.502 <0.0001*

3-Genovese 89.2 28.4 0.632 <0.0001*

4-GCI 100 27.1 0.547 <0.0001*

5-Aroma 2 94.3 31.3 0.757 <0.0001*

6-ILL 99.3 31.5 0.649 <0.0001*

Analysis of Covariance of MTG(days)

Analysis of Covariance of MTG(days)

Analysis of Covariance of MTG(days)

Response Surface

MTG(days)Response Surface Effect by Cultivar

MTG(days)Response Surface Effect by Cultivar

Cultivars Max MTG (days)

Optimal Temp (°C)

R2 P

1-ILL 35X -1.4 30.6 0.934 <0.0001*

2-Nufar -1.0 32.1 0.860 <0.0001*

3-Genovese -1.6 31.6 0.844 <0.0001*

4-GCI -0.3 32.1 0.828 <0.0001*

5-Aroma 2 -0.9 32.2 0.894 <0.0001*

6-ILL -1.4 31.7 0.839 <0.0001*

Future ResearchFind out the optimal germination temp(°C) for each cultivar

High germ% Low MTG(days)

Thank you!