In an elegant study that is the first of its kind, scientists working at USDA’s Henry A Wallace Beltsville Agricultural Research Center used the tools of biotechnology to trace how plants respond to a common organic farming practice – the planting of crops in a hairy vetch (HV) mulch-based system. The study compared the genetic response and health of tomato plants growing in a HV system to tomatoes grown with black plastic (BP) and typical chemical fertilizers and pesticide inputs. The plants grown in the HV mulch-system grew longer and had delayed senescence (65 days in the BP system versus 84 with HV), expressed higher levels of several health-promoting proteins, and were more resistant to common foliar plant diseases (bacterial spot, early blight, Septoria leaf spot). Disease symptoms were apparent in the BP plants from 65 days post-transplanting and grew worse steadily, but did not appear until 84 days after transplanting in the HV system and never became as severe.
The authors report “a distinct expression profile of gene transcripts and proteins…” that reflect changes in hormone signaling in the hairy vetch-grown plants. The impacts of these changes are significant, resulting in “…efficient utilization and mobilization of N, higher photosynthetic rates and, thus, of carbon mobilization…and defense promotion.” The HV plants had larger, healthier root systems, grew slower and longer and produced fruit and foliage more tolerant to disease pressure.
Authors: Vinod Kumar, Douglas Mills, James Anderson, and Autar Mattoo,
Proceedings of the National Academy of Sciences, Early Edition, July 2004