Genotype‐aggregated planting improves yield in Jerusalem artichoke (Helianthus tuberosus) due to self/non‐self‐discrimination

Accumulating evidence indicates that plants are capable of self/non‐self and kin/stranger discrimination. Plants increase biomass of and resource allocation to roots when they encounter roots of conspecific non‐self‐neighbors, but not when they encounter self roots. Root proliferation usually occurs at the expense of reproductive investment. Therefore, if clonal crops are capable of self/non‐self‐discrimination, spatially aggregated planting with seedlings of the same genotype may decrease root proliferation and produce a higher yield than planting without considering seedling genotype. To test this idea, we grew Helianthus tuberosus (Jerusalem artichoke) in pot and field conditions and examined self/non‐self‐discrimination and the effectiveness of genotype‐aggregated planting. Plants grown in self pairs allocated less to root biomass than plants grown in non‐self pairs in both pot and field conditions; in field conditions, the self pairs produced 40% more tubers by weight than the non‐self pairs. When six sprouts from seed tuber of two different genotypes were grown together, with the two genotypes planted aggregately (AGG) or alternately (ALT), plants in the AGG group produced 14% more tubers than plants in the ALT group. These results suggest that spatial aggregation of genotypes increases tuber production in H. tuberosus. Because we found no evidence for trade‐offs between root biomass and tuber production, suppression of root proliferation may not be the only mechanism behind the benefits of genotype aggregation. By applying the concept of self/non‐self‐discrimination, farmers can increase crop production without additional external inputs or expansion of agricultural land use.