Table 1. Statistical parameters for predicting dry-down characteristics of
Kentucky bluegrass cultivars. Smaller (more negative) slope values translate to
more rapid changes in green cover over time. Days50 is the predicted number of
days (from irrigation withheld) until the turf reaches 50% green cover. An
average Days50 was computed (data not shown) and cultivars are sorted by that
average from most drought tolerant to least drought tolerant.
| Rank |
Selection |
Species |
2006 |
2007 |
| Days50 |
(SE) |
Slope |
(SE) |
R² |
Days50 |
(SE) |
Slope |
(SE) |
R² |
| Drought tolerance |
| 1 |
103-509 |
P. pratensis × P. angustifolia |
33.1 |
(0.43) |
-0.105 |
(0.0112) |
0.95 |
32.2 |
(1.12) |
-0.055 |
(0.0082) |
0.76 |
| 2 |
Mallard |
P. pratensis |
31.9 |
(0.19) |
-0.122 |
(0.0063) |
0.99 |
32.9 |
(0.82) |
-0.072 |
(0.0098) |
0.83 |
| 3 |
Longhorn |
P. pratensis × P. arachnifera |
32.7 |
(0.41) |
-0.103 |
(0.0103) |
0.96 |
31.0 |
(2.01) |
-0.034 |
(0.0067) |
0.57 |
| 4 |
Bluestone |
P. pratensis |
30.6 |
(0.48) |
-0.102 |
(0.0115) |
0.95 |
32.6 |
(1.12) |
-0.048 |
(0.0065) |
0.77 |
| 5 |
Arrow |
P. pratensis |
31.7 |
(0.20) |
-0.119 |
(0.0067) |
0.99 |
30.9 |
(1.10) |
-0.051 |
(0.0068) |
0.78 |
| 6 |
AKB449 |
P. pratensis |
30.6 |
(0.34) |
-0.107 |
(0.0088) |
0.98 |
31.4 |
(0.76) |
-0.079 |
(0.0104) |
0.85 |
| 7 |
A00TB-99 |
P. pratensis × P. arachnifera |
29.6 |
(0.19) |
-0.127 |
(0.0069) |
0.99 |
31.7 |
(1.06) |
-0.067 |
(0.0109) |
0.76 |
| 8 |
1QG-38 |
P. pratensis |
31.3 |
(0.26) |
-0.114 |
(0.0078) |
0.98 |
29.9 |
(1.05) |
-0.065 |
(0.0100) |
0.80 |
| 9 |
AKB287 |
P. pratensis |
28.9 |
(0.48) |
-0.092 |
(0.0088) |
0.96 |
29.5 |
(0.94) |
-0.061 |
(0.0080) |
0.84 |
| 10 |
A00TB-101 |
P. pratensis × P. arachnifera |
29.3 |
(0.62) |
-0.109 |
(0.0162) |
0.93 |
28.3 |
(1.16) |
-0.063 |
(0.0101) |
0.78 |
| 11 |
1A4-529 |
P. pratensis × P. densa |
28.4 |
(0.91) |
-0.083 |
(0.0135) |
0.89 |
28.2 |
(1.07) |
-0.063 |
(0.0094) |
0.81 |
| 12 |
1A3-1015 |
P. pratensis |
29.8 |
(0.39) |
-0.113 |
(0.0112) |
0.97 |
26.4 |
(1.58) |
-0.052 |
(0.0098) |
0.68 |
| 12 |
AKB958 |
P. pratensis |
28.8 |
(0.31) |
-0.101 |
(0.0069) |
0.98 |
27.3 |
(1.08) |
-0.060 |
(0.0087) |
0.81 |
| 13 |
A03TB-256 |
P. pratensis × P. arachnifera |
29.6 |
(0.43) |
-0.099 |
(0.0094) |
0.97 |
25.9 |
(1.53) |
-0.042 |
(0.0070) |
0.70 |
| 13 |
Royce |
P. pratensis |
29.7 |
(0.65) |
-0.114 |
(0.0190) |
0.92 |
25.4 |
(1.98) |
-0.048 |
(0.0108) |
0.59 |
| 14 |
A03-TB-676 |
P. pratensis × P. arachnifera |
27.6 |
(0.56) |
-0.101 |
(0.0116) |
0.95 |
26.6 |
(1.18) |
-0.053 |
(0.0077) |
0.79 |
| 14 |
Cadet |
P. pratensis |
27.8 |
(0.53) |
-0.102 |
(0.0115) |
0.96 |
26.2 |
(1.27) |
-0.050 |
(0.0075) |
0.76 |
| 15 |
Broadway |
P. pratensis |
26.7 |
(0.45) |
-0.124 |
(0.0136) |
0.97 |
26.9 |
(1.13) |
-0.056 |
(0.0082) |
0.79 |
| 15 |
Julius |
P. pratensis |
29.0 |
(0.94) |
-0.094 |
(0.0181) |
0.87 |
24.2 |
(1.21) |
-0.044 |
(0.0059) |
0.78 |
| 16 |
A04TB-192 |
P. pratensis × P. arachnifera |
26.7 |
(0.26) |
-0.114 |
(0.0067) |
0.99 |
26.1 |
(0.91) |
-0.063 |
(0.0080) |
0.86 |
| 16 |
Thermal Blue |
P. pratensis × P. arachnifera |
30.2 |
(0.33) |
-0.112 |
(0.0093) |
0.98 |
21.8 |
(1.06) |
-0.058 |
(0.0080) |
0.83 |
| 17 |
A03TB-708 |
P. pratensis × P. arachnifera |
24.8 |
(1.82) |
-0.063 |
(0.0150) |
0.70 |
26.6 |
(1.05) |
-0.061 |
(0.0086) |
0.82 |
| 18 |
Midnight |
P. pratensis |
27.2 |
(0.81) |
-0.093 |
(0.0140) |
0.92 |
23.9 |
(1.34) |
-0.053 |
(0.0086) |
0.76 |
| 19 |
1A4-312 |
P. pratensis × P. angustifolia |
26.3 |
(0.81) |
-0.104 |
(0.0169) |
0.92 |
24.7 |
(1.04) |
-0.057 |
(0.0075) |
0.83 |
| 20 |
103-630 |
P. pratensis × P. angustifolia |
23.0 |
(1.87) |
-0.061 |
(0.0137) |
0.72 |
27.9 |
(0.83) |
-0.068 |
(0.0084) |
0.87 |
| 21 |
A03TB-390 |
P. pratensis × P. arachnifera |
26.3 |
(0.42) |
-0.128 |
(0.0132) |
0.97 |
23.9 |
(1.22) |
-0.052 |
(0.0075) |
0.79 |
| 22 |
A03TB-417 |
P. pratensis × P. arachnifera |
26.9 |
(0.67) |
-0.110 |
(0.0159) |
0.94 |
23.0 |
(1.93) |
-0.041 |
(0.0084) |
0.60 |
| 23 |
1A4-221 |
P. pratensis × P. nemoralis |
26.8 |
(0.32) |
-0.131 |
(0.0108) |
0.98 |
22.3 |
(0.99) |
-0.053 |
(0.0065) |
0.85 |
| 24 |
Pp H8510 |
P. pratensis |
27.1 |
(0.28) |
-0.127 |
(0.0090) |
0.99 |
21.3 |
(1.16) |
-0.054 |
(0.0078) |
0.81 |
| 25 |
Fire & Ice |
P. pratensis × P. arachnifera |
25.9 |
(0.47) |
-0.116 |
(0.0118) |
0.97 |
21.0 |
(1.62) |
-0.048 |
(0.0088) |
0.69 |
| 26 |
A03TB-795 |
P. pratensis × P. arachnifera |
27.6 |
(0.55) |
-0.112 |
(0.0140) |
0.95 |
19.1 |
(1.46) |
-0.047 |
(0.0076) |
0.73 |
| 27 |
Solar Green |
P. pratensis × P. arachnifera |
25.7 |
(0.51) |
-0.098 |
(0.0092) |
0.97 |
18.4 |
(1.88) |
-0.044 |
(0.0090) |
0.62 |
Table 2. Statistical parameters for predicting green-up of bluegrass
cultivars after water was applied. Larger slope values translate to more rapid
changes in green cover over time. Days50 is the predicted number of days (from
irrigation applied) until the turf reaches 50% green cover. An average Days50
was computed (data not shown) and cultivars are sorted by that average from
fastest recovery from drought to slowest recovery from drought.
| Rank |
Selection |
Species |
2006 |
2007 |
| Days50 |
(SE) |
Slope |
(SE) |
R² |
Days50 |
(SE) |
Slope |
(SE) |
R² |
| Drought recovery |
| 1. |
Longhorn |
P. pratensis × P. arachnifera |
4.4 |
(0.43) |
0.159 |
(0.0280) |
0.85 |
5.9 |
(1.70) |
0.053 |
(0.0129) |
0.66 |
| 2. |
Bluestone |
P. pratensis |
6.9 |
(0.35) |
0.156 |
(0.0209) |
0.91 |
4.2 |
(1.54) |
0.040 |
(0.0064) |
0.80 |
| 3. |
103-509 |
P. pratensis × P. angustifolia |
5.6 |
(0.27) |
0.132 |
(0.0123) |
0.95 |
6.5 |
(1.00) |
0.057 |
(0.0088) |
0.86 |
| 4. |
Mallard |
P. pratensis |
6.8 |
(0.38) |
0.148 |
(0.0207) |
0.91 |
5.7 |
(0.62) |
0.073 |
(0.0090) |
0.91 |
| 5. |
AKB449 |
P. pratensis |
8.2 |
(0.47) |
0.120 |
(0.0163) |
0.89 |
6.6 |
(1.94) |
0.035 |
(0.0064) |
0.73 |
| 6. |
Arrow |
P. pratensis |
7.1 |
(0.30) |
0.161 |
(0.0187) |
0.94 |
8.9 |
(1.45) |
0.042 |
(0.0070) |
0.81 |
| 7. |
A00TB-99 |
P. pratensis × P. arachnifera |
8.7 |
(0.50) |
0.159 |
(0.0282) |
0.88 |
7.4 |
(0.95) |
0.074 |
(0.0133) |
0.83 |
| 8. |
1QG-38 |
P. pratensis |
7.3 |
(0.34) |
0.165 |
(0.0218) |
0.92 |
9.9 |
(1.22) |
0.068 |
(0.0134) |
0.80 |
| 9. |
AKB287 |
P. pratensis |
6.7 |
(0.35) |
0.138 |
(0.0168) |
0.92 |
10.6 |
(1.84) |
0.036 |
(0.0061) |
0.75 |
| 10. |
Royce |
P. pratensis |
8.3 |
(0.42) |
0.177 |
(0.0299) |
0.90 |
9.6 |
(1.20) |
0.077 |
(0.0163) |
0.80 |
| 11. |
A03TB-256 |
P. pratensis × P. arachnifera |
7.5 |
(0.33) |
0.151 |
(0.0182) |
0.93 |
10.7 |
(1.79) |
0.046 |
(0.0097) |
0.71 |
| 12. |
A03-TB-676 |
P. pratensis × P. arachnifera |
9.6 |
(0.40) |
0.184 |
(0.0281) |
0.92 |
9.5 |
(1.19) |
0.074 |
(0.0152) |
0.78 |
| 12. |
A00TB-101 |
P. pratensis × P. arachnifera |
9.1 |
(0.24) |
0.152 |
(0.0123) |
0.97 |
11.0 |
(1.33) |
0.063 |
(0.0122) |
0.80 |
| 13. |
AKB958 |
P. pratensis |
8.0 |
(0.39) |
0.145 |
(0.0195) |
0.91 |
12.7 |
(2.05) |
0.039 |
(0.0079) |
0.73 |
| 13. |
A03TB-417 |
P. pratensis × P. arachnifera |
8.9 |
(0.52) |
0.161 |
(0.0296) |
0.87 |
12.5 |
(2.09) |
0.037 |
(0.0074) |
0.72 |
| 14. |
103-630 |
P. pratensis × P. angustifolia |
10.9 |
(1.77) |
0.054 |
(0.0145) |
0.52 |
10.6 |
(1.05) |
0.046 |
(0.0058) |
0.89 |
| 14. |
A03TB-708 |
P. pratensis × P. arachnifera |
8.9 |
(0.97) |
0.084 |
(0.0171) |
0.70 |
13.1 |
(1.07) |
0.063 |
(0.0096) |
0.88 |
| 15. |
A04TB-192 |
P. pratensis × P. arachnifera |
9.1 |
(0.55) |
0.097 |
(0.0125) |
0.88 |
13.1 |
(1.44) |
0.046 |
(0.0072) |
0.83 |
| 15. |
Cadet |
P. pratensis |
8.1 |
(0.24) |
0.148 |
(0.0121) |
0.97 |
14.2 |
(1.75) |
0.036 |
(0.0057) |
0.79 |
| 16. |
1A4-529 |
P. pratensis × P. densa |
8.7 |
(0.97) |
0.081 |
(0.0160) |
0.72 |
14.6 |
(2.13) |
0.033 |
(0.0060) |
0.73 |
| 16. |
Midnight |
P. pratensis |
9.8 |
(0.35) |
0.167 |
(0.0204) |
0.94 |
14.0 |
(1.22) |
0.059 |
(0.0093) |
0.88 |
| 17. |
1A4-221 |
P. pratensis × P. nemoralis |
10.4 |
(0.31) |
0.170 |
(0.0182) |
0.95 |
14.3 |
(1.51) |
0.049 |
(0.0082) |
0.82 |
| 18. |
Julius |
P. pratensis |
8.0 |
(0.56) |
0.130 |
(0.0225) |
0.84 |
17.2 |
(1.96) |
0.030 |
(0.0046) |
0.78 |
| 19. |
Broadway |
P. pratensis |
9.3 |
(0.26) |
0.181 |
(0.0182) |
0.96 |
16.7 |
(1.82) |
0.035 |
(0.0053) |
0.80 |
| 20. |
Pp H8510 |
P. pratensis |
9.1 |
(0.40) |
0.143 |
(0.0179) |
0.92 |
17.0 |
(1.95) |
0.036 |
(0.0062) |
0.77 |
| 21. |
Solar Green |
P. pratensis × P. arachnifera |
8.1 |
(0.22) |
0.210 |
(0.0210) |
0.97 |
18.5 |
(4.35) |
0.022 |
(0.0065) |
0.43 |
| 22. |
1A3-1015 |
P. pratensis |
8.2 |
(0.21) |
0.162 |
(0.0124) |
0.97 |
18.9 |
(3.63) |
0.027 |
(0.0073) |
0.53 |
| 23. |
Fire & Ice |
P. pratensis × P. arachnifera |
8.5 |
(0.24) |
0.186 |
(0.0184) |
0.96 |
18.7 |
(3.79) |
0.024 |
(0.0065) |
0.49 |
| 24. |
1A4-312 |
P. pratensis × P. angustifolia |
10.1 |
(0.69) |
0.109 |
(0.0184) |
0.84 |
17.3 |
(1.77) |
0.037 |
(0.0056) |
0.80 |
| 25. |
A03TB-795 |
P. pratensis × P. arachnifera |
8.8 |
(0.33) |
0.138 |
(0.0144) |
0.94 |
18.7 |
(2.23) |
0.034 |
(0.0060) |
0.73 |
| 26. |
A03TB-390 |
P. pratensis × P. arachnifera |
9.8 |
(0.48) |
0.115 |
(0.0143) |
0.90 |
18.8 |
(2.25) |
0.033 |
(0.0059) |
0.74 |
| 27. |
Thermal Blue |
P. pratensis × P. arachnifera |
5.3 |
(0.48) |
0.121 |
(0.0181) |
0.87 |
31.1 |
(2.47) |
0.024 |
(0.0039) |
0.72 |