Effects of intra-variety root competition and soil fertility on resource
allocation in a modern wheat variety and an old landrace
Abstract
Darwinian agriculture (also called Evolutionary agroecology) which
focuses on the trade-off between individual fitness and community
performance, can provide an efficient approach to enhance crop
production. However, evolutionary or ecological processes, in particular
the tragedy of the commons in crops, remain poorly understood. We used a
pot experiment to examine whether wheat plants fell into this ‘tragedy’
when confronted with roots of an intra-variety neighbour and how the
magnitude was influenced by soil fertility. Two varieties (old landrace
Monkhead and modern variety 92-46) were selected for this study. Root
competition scenarios were set by growing two plants of the same variety
with a mesh or plastic partition. Soil fertility gradients were set by
adding nutrient solutions with low or high application frequency.
Biomass were tested and allometric relationship were analyzed to reveal
resource allocation pattern. Old Monkhead had similar relative
allocation to root biomass with modern 92-46, but had greater relative
allocation to stem&leaf biomass and lower relative allocation to seed
biomass. The presence of neighbour affected allometric relationships
only in 4 out of 24 allometic comparisons, which all appeared in low
fertility treatments. Fertilizer addition increased stem&leaf biomass
allocation of Monkhead and decreased root and seed biomass allocation at
the same time. By contrast, stem&leaf and seed allocation of 92-46 was
not changed by fertilizer addition although root allocation was
decreased. Our results demonstrated that there was a trade-off between
non-reproductive and reproductive allocation for wheat varieties. There
was not notable tragedy of the commons in wheat varieties, although a
small degree was observed in Monkhead. Moreover, the occurrence and
magnitude of the tragedy was dependent on resource availability and
variety resource-use strategy. Our results underlie the importance of
understanding the mechanisms behind the tragedy of the commons in crop
varieties with different ecological strategies, and provide insights
into the role of Darwinian agriculture in global food production.