Parallel tracks in European corn (i.e., wheat) fields, visible from the air, and produced by tractor wheels when spraying the crop with pesticides . Transgressive segregation

The phenomenon in which some of the progeny have a higher level of a quantitative character, such as horizontal resistance, than either of their parents. Suppose that two parents, which are highly susceptible, each have only 10% of all of the alleles contributing to horizontal resistance to a parasite. If each parent has a different 10% of alleles, some of their progeny will have more than 10% of the total available alleles. These individuals in the progeny will then be more resistant than either of their parents. Transgressive segregation can continue in each generation of recurrent mass selection until no further progress is possible, because the maximum number of alleles has been accumulated. Transmission

Many virus diseases are transmitted by plant parasitic insects that migrate from one host to another. This transmission clearly involves allo-infections.

Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

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