Abstract
Some scientists consider the loss of the American chestnut from forests in the eastern United States as one of the greatest forest ecological disasters in the 20th century. The American Chestnut Foundation has been attempting to restore chestnut by backcrossing blight-resistant Chinese chestnut to American chestnut and selecting those strains with blight resistance. Third-generation backcross seeds and seedlings have been produced and planted by researchers. Surface-mined lands provide a land base where these backcross chestnut seedlings may be introduced back into forests. In 2008, seeds of two parent species of chestnut (100% American and 100% Chinese) and three breeding generations (BF, BF, and BF backcrosses) were planted into loosely graded mine soils with and without tree shelters. First-year establishment from seeds averaged 81%. After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%. Survival with shelters was only slightly better after the fourth year (average, 60% with shelters and 57% without). Height growth was not different among stock types, and average height after the fourth year was 43 cm without shelters and 56 cm with shelters. In 2009, seeds and seedlings of the same chestnut stock types were planted into brown (pH 4.5) or gray (pH 6.6) mine soils. Only six out of 250 seeds germinated, which was very poor considering 81% average seed germination in 2008. Transplanted chestnut seedling survival was much better. After the third year, seedling survival was 85% in brown and 80% in gray soil, but significant differences were found with stock types. Survival was significantly higher with American, Chinese, and BF stock types (75%) than with BF and BF (60%). Height after the third season averaged 90 cm on brown and 62 cm on gray soil. Chestnut backcrosses displayed no hybrid vigor and were not better in survival and growth than the parent stock. All five stock types grew on mine soils in West Virginia, and we found surface mines to be promising sites for introducing blight-resistant chestnut backcross trees into the Appalachian forest.
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Claims 20
Claim · model-written summary
First-year establishment from chestnut seeds averaged 81%.
Verbatim
e1“First-year establishment from seeds averaged 81%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Without shelters, the American chestnut stock had 40% survival after the fourth year.
Verbatim
e2“After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Without shelters, the Chinese chestnut stock had 80% survival after the fourth year.
Verbatim
e2“After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Without shelters, the BF backcross stock type had 70% survival after the fourth year.
Verbatim
e2“After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Without shelters, a second BF backcross stock type had 40% survival after the fourth year.
Verbatim
e2“After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Without shelters, a third BF backcross stock type had 55% survival after the fourth year.
Verbatim
e2“After the fourth year, survival without shelters declined for all chestnut stock types except for Chinese (80%): American 40%, BF 70%, BF 40%, and BF 55%”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Survival with shelters after the fourth year was 60% and only slightly better than without shelters.
Verbatim
e3“Survival with shelters was only slightly better after the fourth year (average, 60% with shelters and 57% without)”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Survival without shelters after the fourth year averaged 57%.
Verbatim
e3“Survival with shelters was only slightly better after the fourth year (average, 60% with shelters and 57% without)”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Height growth of chestnut stock types was not different.
Verbatim
e4“Height growth was not different among stock types, and average height after the fourth year was 43 cm without shelters and 56 cm with shelters”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Average height after the fourth year was 43 cm without shelters.
Verbatim
e4“Height growth was not different among stock types, and average height after the fourth year was 43 cm without shelters and 56 cm with shelters”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Average height after the fourth year was 56 cm with shelters.
Verbatim
e4“Height growth was not different among stock types, and average height after the fourth year was 43 cm without shelters and 56 cm with shelters”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Only six of 250 seeds sown in 2009 germinated.
Verbatim
e5“Only six out of 250 seeds germinated, which was very poor considering 81% average seed germination in 2008”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Transplanted chestnut seedling survival after the third year was 85% in brown mine soil.
Verbatim
e6“After the third year, seedling survival was 85% in brown and 80% in gray soil”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Transplanted chestnut seedling survival after the third year was 80% in gray mine soil.
Verbatim
e6“After the third year, seedling survival was 85% in brown and 80% in gray soil”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Seedling survival was significantly higher for American, Chinese and BF stock types (75%) than for BF and BF stock types (60%).
Verbatim
e7“Survival was significantly higher with American, Chinese, and BF stock types (75%) than with BF and BF (60%)”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Seedling survival of the BF and BF stock types was 60%.
Verbatim
e7“Survival was significantly higher with American, Chinese, and BF stock types (75%) than with BF and BF (60%)”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Height after the third season averaged 90 cm on brown mine soil.
Verbatim
e0“Height after the third season averaged 90 cm on brown and 62 cm on gray soil”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Height after the third season averaged 62 cm on gray mine soil.
Verbatim
e0“Height after the third season averaged 90 cm on brown and 62 cm on gray soil”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Chestnut backcrosses showed no hybrid vigor and were not better than the parent stock in survival and growth.
Verbatim
e1“Chestnut backcrosses displayed no hybrid vigor and were not better in survival and growth than the parent stock”
t0“Chestnut Backcross Seeds and Seedlings”
Claim · model-written summary
Surface mines are promising sites for introducing blight-resistant chestnut backcross trees into the Appalachian forest.
Verbatim
e2“we found surface mines to be promising sites for introducing blight-resistant chestnut backcross trees into the Appalachian forest”
t0“Chestnut Backcross Seeds and Seedlings”