摘要:植物相同基因型个体之间竞争地下资源会导致根系增生，这被称为根系竞争的“公地悲剧”现象。减少或者消除作物的根系增生有望提高种子产量。但人工育种是否已经无意识地影响了作物的根系竞争效应，目前研究尚不足。本研究选取春小麦古老品种‘和尚头’和现代品种‘92-46’开展温室盆栽试验，通过设置尼龙隔离、无竞争塑料隔离和有竞争塑料隔离，并设置1倍营养和2倍营养两个营养水平，分析根系竞争对春小麦各器官生物量的影响，并采用标准化主轴回归（SMA）方法分析根系竞争对资源分配的影响。结果表明，与无竞争塑料隔离相比，尼龙隔离的根系生物量无显著变化，但茎叶生物量和总生物量显著提高。尼龙隔离的古老品种‘和尚头’种子生物量与无竞争塑料隔离无显著差异，而现代品种‘92-46’的种子生物量显著高于无竞争塑料隔离。2倍营养-有竞争塑料隔离与1倍营养-无竞争塑料隔离相比，根系生物量和种子生物量无显著差异，但茎叶生物量和总生物量显著降低。标准化主轴回归（SMA）分析发现，根系竞争对‘和尚头’的根系资源分配无显著影响，根系竞争显著降低了‘92-46’的根系资源分配但降低程度较小（尼龙隔离相比无竞争塑料隔离）；根系竞争对两个品种的茎叶资源分配和种子资源分配均无显著影响。另外，本研究还发现：‘和尚头’的根系生物量和茎叶生物量大于‘92-46’，而种子生物量小于‘92-46’。除1倍营养-无竞争塑料隔离处理，其他隔离处理下‘和尚头’的根系资源分配与‘92-46’无显著差异；且‘和尚头’的茎叶资源分配大于‘92-46’，种子资源分配小于‘92-46’。总之，现代品种‘92-46’可能发展出一定程度的合作行为，通过根系分泌物介导识别邻株根系并减少根系资源分配；现代品种‘92-46’资源更多分配到繁殖生长，而古老品种‘和尚头’更多分配到茎叶生长。
关键词:达尔文农学/
“公地悲剧”/
根系竞争/
合作行为/
春小麦品种/
生物量/
资源分配
Abstract:Belowground competition among individuals of the same genotype can result in root proliferation, a pattern called "tragedy of the commons". Reducing or eliminating root proliferation could increase seed yield. However, it is not clear whether root competition effect has been influenced by breeding. A greenhouse pot experiment was conducted using an old spring wheat landrace 'Monkhead' and a modern cultivar '92-46'. Root interactions were set up by adding a mesh partition or a plastic partition between two plants from the same variety. Root competition was also encouraged by placing two plants on the same side of the plastic partition. There were two nutrition treatments: 1 time nutrition application and 2 times nutrition application. We examined the effect of root competition by comparing biomass and resource allocation patterns among the partition treatments. Biomass data showed that plants in the 'mesh partition' treatment produced similar root biomass to those in the 'plastic partition' treatment without competition, but their shoot biomass and total biomass were higher. 'Monkhead' plants in the 'mesh partition' treatment produced similar seed biomass to those in the 'plastic partition' treatment without competition, whereas seed biomass of '92-46' plants in the 'mesh partition' treatment was higher. Root biomass and seed biomass in the '2 times nutrition-plastic partition with competition' treatment were similar to those in the '1 time nutrition-plastic partition without competition' treatment, but their shoot biomass and total biomass were lower. A standardized major axis regression analysis (SMA) showed that root allocation of 'Monkhead' was not affected by root competition, but root allocation of '92-46' was decreased slightly ('mesh partition' vs. 'plastic partition without competition'). Root competition had no effect on shoot allocation and seed allocation for both varieties. In addition, Our results revealed composition differences between two varieties. 'Monkhead' produced more roots and shoots, but less seeds than '92-46'. 'Monkhead' also allocated more resources to shoots and less to seeds than '92-46', whereas root allocation was similar between two varieties in most partition sets except for '1 time nutrition-plastic partition without competition'. We conclude that the presence of roots from a neighboring plant does not result in 'the tragedy of the commons' pattern in either 'Monkhead' or '92-46', but affect the resource allocation pattern in '92-46' to some extent. Modern '92-46' is somehow able to develop restraining and cooperative behaviour characteristics in the presence of roots from neighboring plants, whereas 'Monkhead' does not show any responses. The differences in resource allocation patterns between two varieties support Darwinian agriculture, which suggests that in order to enhance yield, crop breeding has consciously selected varieties associated with lower competitiveness.
Key words:Darwinian agriculture/
Tragedy of the commons/
Root competition/
Cooperation/
Spring wheat varieties/
Biomass/
Resource allocation
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