New Zealand Journal of Crop and Horticultural Science abstracts
Empirical models of the relationships between early blight (Alternaria
solani) and yield of potato (Solanum tuberosum) crop grown under
different production environments
S. F. A. Shah*
B. A. McKenzie
R. E. Gaunt†
Soil, Plant and Ecological Sciences Division
Lincoln University
Canterbury, New Zealand
John W. Marshall
New Zealand Institute for Crop & Food
Research Ltd
Private Bag 4704
Christchurch, New Zealand
C. M. Frampton
Christchurch School of Medicine
University of Otago
P.O. Box 4345
Christchurch, New Zealand.
*Present address: New Zealand Institute for Crop & Food Research
Ltd,
Private Bag 4704, Christchurch, New Zealand. Email: Shahf@crop.cri.nz
†Deceased.
Abstract Four experiments were conducted over two growing
seasons during 1995/96 and 1996/97 at Lincoln University and the New Zealand
Institute for Crop & Food Research, Lincoln, Canterbury. A large database
was used to assess the effects of production environments on disease yield
relationships and to compare different models derived from pathogen-based
disease measurement and host-based disease measurements. All the models were
developed using regression analyses. All the single point (SP), multiple
point (MP), and integral models derived from host-based disease measurements
explained more variation than models derived from pathogen-based disease
measurements. SP, MP, and integral models were also compared and integral
models were selected as the best for comparing disease effects as they combine
the effect of disease over the whole growing season in one variable. Further,
integral models were tested for the effect of different production environments
on disease yield relationships. It was found that the nitrogen-altered production
environments had no significant effect on disease yield relationships, whereas
potato cyst nematode-altered production environments significantly affected
the disease yield relationship. A single model was used for the disease yield
relationship for nitrogen inputs, whereas separate disease yield relationships
were used for each nematode level.
Keywords disease: yield models; potato; Solanum tuberosum;
early blight; Alternaria solani; nitrogen; potato cyst nematode; Globodera
rostochiensis; radiation interception; green leaf area index; percent
reflectance
H03029; Online publication date 17 March 2004 ; Received 24 March 2003;
accepted 17 October 2003
New Zealand Journal of Crop and Horticultural Science, 2004, Vol. 32:
103-112
0014-0671/04/3201-0103 © The Royal Society of New Zealand 2004
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