Effects Of Seed Vigor Research Articles

Effect of Seed Vigor on Intraspecific Competition and Grain Yield in Maize

High‐vigor seeds result in faster emergence of seedlings and crop establishment than low‐vigor seeds. These characteristics could enhance plant competitive ability and could have direct effects on maize (Zea mays L.) grain yield. This study examined the hypothesis that seed vigor heterogeneity in maize seed lots could increase intraspecific competition and negatively affect crop grain yield. A 2‐yr experiment was executed combining two hybrid maize seed lots, possessing high‐vigor and low‐vigor seeds, in seven different distributions in the sowing row. The distributions of the plants originating from high‐ and low‐vigor seeds were evaluated at harvest for dry mass accumulation, prolificacy, number of grains per row, number of rows per ear, 1000‐grain mass, and grain yield. A replacement series design for data analysis of two homogeneous populations and five seed mixture populations was applied. We concluded that, in plant populations originating from heterogeneous seed lots, intraspecific competition was intensified, resulting in losses of dry mass accumulation and grain yield. Plants originating from low‐vigor seeds had less competitive ability and reduced plant dry mass accumulation and grain yield than those originating from high‐vigor seeds and were responsible for crop yield losses. Plants originating from high‐vigor seeds had a dominant effect on those originating from low‐vigor seeds and had no compensatory effects. The major production component affected by intraspecific competition was the number of grains per row.

Seed Vigor and Field Performance of Winter Oilseed Rape (Brassica napus L.) Cultivars

The effect of seed vigor on field performance of two oilseed rape cultivars (Licord and Okapi) was investigated in 2008 at the Research Farm of the University Tabriz, Iran. The experiment was arranged as factorial based on RCB design with three replications. A sub-sample of seeds of each cultivar was kept as control. The other two sub-samples of each cultivar with about 15% moisture content were artificially deteriorated at 40C for 9 and 12 days (Licord) and 7 and 10 days (Okapi). Consequently, three seed lots for each cultivar with different levels of vigor were provided. The results showed that the mean emergence time increased with decreasing seed vigor. However, the highest percentage of seedling emergence was obtained for the high quality seed lot and decreased with decreasing seed lot vigor. Decreasing seed vigor led to significant reduction in ground cover of both cultivars; mainly due to poor stand establishment. Ground cover of Licord was higher than that of Okapi. Plants from high vigor seed lots of both cultivars had higher leaf chlorophyll content index at early stages of growth, compared with those from low quality seed lots. Grains per plant, 1000 grain weight and grain yield per plant for plants from deteriorated seed lots were higher than those from high-vigor seed lot. However, these advantages in individual plant performance were not sufficient to compensate for low stand establishment. Consequently, grain yield per unit area significantly improved with increasing seed vigor of oilseed rape cultivars, even within the range of acceptable germination.

Effects of Seed Vigor on Crop Characters in Uniform and Reduced Populations of Corn (Zea mays L.)

AbstractThe relationship between seed corn vigor and some crop characters in uniform and reduced plant populations is poorly defined. This study, was designed to define the crop characters through which seed vigor is expressed in reduced and uniform populations of corn and to clarify which experimental technique should be used in seed vigor studies. Seeds of two corn hybrids, A632 x (H99 x H95) and B73 x (H99 x H95), were dried at two temperatures, 35 °C and 50 oC, and planted near Ames, Iowa, in 1983. The two drying temperatures created differential vigor levels between the seed lots. There were 21 crop characters measured in two populations, reduced populations due to lack of seed vigor and uniform population (thinning to stand). Early vegetative growth was influenced by seed vigor, but as the plant aged, the influence of seed vigor decreased. Increased early plant height, up to 6 weeks old, small stem diameter, low shoot dry‐matter content, delay in days from sowing to 50 % tasseling and to 50 % silking, narrow penultimate and ear leaf, and reduction in the number of ears and tiller production were observed in the uniform population. The differences in population density due to seed vigor did not have a significant effect on final grain yield inasmuch as plants in the reduced populations were able to compensate completely for missing stands.