AOBPreview originally published online on August 3, 2004
Annals of Botany 2004 94(3):385-392; doi:10.1093/aob/mch154
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Annals of Botany 94/3, © Annals of Botany Company 2004; all rights reserved
The Use of a Principal Axis Model to Examine Individual Plant Harvest Index in Four Grain Legumes
1 Plant Sciences Group, Agriculture and Life Sciences Division, PO Box 84, Lincoln University, Canterbury, New Zealand and 2 DNRE, Victorian Institute for Dryland Agriculture, PMB 260, Horsham, Victoria 3401, Australia
* For correspondence. E-mail moot{at}lincoln.ac.nz
Received: 20 August 2003 Returned for revision: 20 February 2004 Accepted: 14 May 2004 Published electronically: 3 August 2004
• Background and Aims A principal axis model (PAM) has been proposed to enable the selection of crop ideotypes. The PAM enables plant-to-plant variability within crops to be quantified and compared. The aim of this paper is to validate the PAM for four grain legumes.
• Methods Four grain legumes (Cicer arietinum, Lens culinaris, Lupinus angustifolius, Pisum sativum) were used to quantify the influence of plant-to-plant variability on crop yields. To create variability, populations of 10, 100 and 400 plants m–2 were established ‘on-the-square’ with sowing depths of 2, 5 and 10 cm. Further, a central plant was treated with nitrogen and the impact of this on its four neighbouring plants was examined. Seeds were sown and plants harvested individually by hand.
• Key Results Mean individual plant seed weight (SWT) and plant weight (PWT) decreased as plant population increased but there was a consistent and strong (R2 > 0·90) linear relationship between SWT and PWT, with a negative SWT-axis intercept in all species. These components form the basis of the principal axis model (PAM). The PAM was used to summarize the performance of individual plants within a crop and quantify the variability caused by N treatment and the lowest and highest yielding individual plants. A negative SWT-axis intercept indicated that a minimum plant weight (MPW) was required for seed production and therefore the relationship between plant harvest index (PHI) and PWT was asymptotic. The heaviest MPW was calculated for plants grown at the lowest plant population and it was species-dependent, being higher in the larger seeded species.
• Conclusions Agronomic or physiological characteristics that lead to variability in PWT within a population will decrease PHI, and crop yield. The PAM may be useful in breeding programmes to identify plant phenotypes that minimize this plant-to-plant variability.
Key words: Chickpea (Cicer arietinum), field pea (Pisum sativum), individual plants, lentils (Lens culinaris), narrow-leafed lupin (Lupinus angustifolius), plant harvest index, plant weight, principal axis model (PAM)