Yield versus pest resistance Minimize

February 2011. An article in SciDevNet 7-13 Feb 2011, discussing the idea that breeding plants for faster growth and higher yield will lead to plant vulnertable to plant pests and diseases. Researchers found that genes for yield and fast growth were closely linked to defence against pests.

This article provoked a response from one member who asked whether crop protectionists haven't been saying this since the modern 'science' of crop breedingwas invented, only to be totally ignored by thodse whom yield is all?

It is also not true (as the article says) that farmers 'select' for high yield. Farmers 'select' seed for the next sowing from the plants that survive and which have other characters they like, e.g., taste, flavour, length of stover, etc. The chances are that these genotypes are locally adapted (to soil type, etc.) and have resistance to the critical pests and diseases of that locality - so we are really talking about farmer induced natural selection.

An example was provided, involving Chalimbana, a groundnut variety with high yield, jumbo size kernels that has grown well (and tasted good), for a long time in Malawi and neighbouring countries. It was found by accident that it had high levels of resistance to Aphis craccivora, the vector of the rosette virus complex. (It was the 'local control' in aphid resistance screening trials and scored better than all other genotypes). It was subsequentally observed that rosette was uncommon wherever Chalimbana was grown in the farmers' fields and in trials. Neighbouring, ostensibly high yielding 'elite', breeding material succumbed. The farmers and nature had done the job. Were breeders interested? No - high yield and the elusive virus resistance were the goals.