Seed vigor enhances tomato's competitiveness against weeds

Tomato seeds with high vigor increased the initial competitive capacity of seedlings with Setaria viridis and datura stramonium. The effect was most pronounced in competition for soil resources. The result indicates seed vigor as a strategic component in integrated weed management in no-till processing tomatoes.

The study evaluated high-vigor tomato seeds, with 91 percent germination, and low-vigor seeds, with 60 percent germination. The researchers obtained the low-vigor batch through accelerated aging, with a temperature of 42 degrees Celsius and relative humidity close to 100 percent for 72 hours.

Two weed species

The study compared the performance of tomatoes against two weed species. Setaria viridis, known as green foxtail grass, exhibited rapid growth and strong root development. Datura stramonium, known as the devil's fig tree, represented a broad-leaved species with a different resource acquisition strategy.

High-vigor tomato seeds achieved 83 percent emergence in the greenhouse. Low-vigor seeds reached 56 percent. The average emergence time did not differ statistically between the two tomato batches. High-vigor seeds emerged in 6,0 days. Low-vigor seeds emerged in 7,2 days.

Even without a statistically significant difference at this point, the high-vigor group showed a numerical advantage in the initial phase. Seedlings in this group accumulated 8,5 milligrams of dry mass. Those with low vigor accumulated 7,1 milligrams. This difference suggests a greater potential for initial growth.

Weeds before

The weeds emerged before the tomatoes. Datura stramonium showed an average emergence time of 2,4 days. Setaria viridisIt took 3,0 days. This initial advance favored the so-called priority effect, in which the plant that emerged first occupies space and captures resources before the crop.

The growth analysis showed a significant advantage for Setaria viridis. At 40 days after emergence, the species reached approximately 80 centimeters in height. The high-vigor tomato, the low-vigor tomato, and Datura stramonium were close to 40 centimeters apart.

The most significant difference occurred in the roots. Setaria viridisIt produced approximately 1.200 milligrams of root dry matter 40 days after emergence. The other plants produced between 200 and 250 milligrams. This pattern indicates a high capacity for exploiting water and nutrients in the soil.

Tomato yield

In replacement series trials, the high-vigor tomato maintained relative leaf and root yield within the expected range when competing with Datura stramonium. The low-vigor tomato plant experienced low-level weed suppression, with a decrease in relative root yield below the adopted statistical limit.

The competition with Setaria viridis had a more severe effect. Low-vigor tomatoes lost their ability to occupy root niches in all proportions evaluated. In a mixture with 75 percent of Setaria viridis, the relative yield of low-vigor tomato roots fell to values ​​between 0,10 and 0,15.

High-vigor tomatoes also suffered competition with Setaria viridis, however it maintained superior performance. The researchers interpreted this result as an indication of physiological dampening promoted by seed vigor.

Aerial and underground

The separation between aboveground and belowground competition confirmed this difference. In treatments with belowground competition, high-vigor plants produced 0,25 grams of root mass per plant. Low-vigor plants produced 0,15 grams per plant.

The results reinforce the importance of seed physiological quality in no-till systems. According to the study, high-vigor seed lots can reduce the vulnerability of tomatoes at the beginning of their cycle. This phase defines part of the competitive relationship with weeds.

The researchers highlight the need for field studies. The research was conducted in a greenhouse. Trials under varying agronomic conditions are still needed to confirm the effects on final productivity and on integrated weed management programs.

Further information can be found at doi.org/10.3390/seeds5030033