New Zealand Journal of Crop and Horticultural Science abstracts

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Effect of early blight (Alternaria solani) and different nitrogen inputs on radiation interception, radiation use efficiency, and total dry matter production in potatoes (Solanum tuberosum) grown in Canterbury, New Zealand

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 and Food
 Research Limited
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 and Food Research Limited,
Private Bag 4704, Christchurch, New Zealand. email: Shahf@crop.cri.nz

†Deceased.

Abstract  Field experiments were conducted in 1995/96 and 1996/97 to investigate the effect of early blight epidemics on photosynthetically active radiation (PAR) interception (RI), radiation use efficiency (RUE), and total dry matter (TDM) production of potatoes (Solanum tuberosum) grown in Canterbury, New Zealand. RI was calculated from green leaf area index (GLAI) corrected for disease. RUE was calculated as the ratio between accumulated TDM and accumulated RI. Early blight reduced RI by 9% in both seasons and RUE by 17% and 28% in 1995/96 and 1996/97 respectively. There was a total loss of 26% and 36% in TDM in 1995/96 and 1996/97 respectively. Nitrogen inputs increased RUE by 3% and 16% as compared to low nitrogen status in 1995/96 and 1996/97 respectively. Results showed that RI and RUE, calculated from leaf area index (LAI), not corrected for disease, underestimated the loss in RI and RUE.

Keywords  early blight; Alternaria solani; nitrogen; radiation interception; radiation use efficiency; and dry matter production

H03116; Received 24 December 2003; accepted 15 July 2004; Online publication date 9 September 2004
New Zealand Journal of Crop and Horticultural Science, 2004, Vol. 32: 263-272
0014-0671/04/3203-0263 $7.00 © The Royal Society of New Zealand 2004

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