Safflower (Carthamus tinctorius L.) seed vigor tests for the prediction of field emergence

Abstract

It is important to predict how plant seeds may germinate in the field using the lab tests. Accordingly, lab and field experiments were conducted to determine safflower (Carthamus tinctorius L.) seed emergence. The vigor tests including electrical conductivity (EC) of seed leachate, seed germination and seedling growth rate were performed. The research work consisted of multi-stage experiments during seed germination (in the lab), seedling growth (in the growth chamber) and seed germination and yield production (in the field). At the germination stage (in the lab, split plot experiment) seed lot (SL), seed size (SS), and seed age (AA) were used as the experimental treatments to determine EC of leachate and germination percentage (GP) from day 1 to 6 (temperatures of 10 and 20°C). Moreover, total seed germination, rate of germination, mean of germination time and germination index were determined. At the seedling growth stage (in the growth chamber, split plot experiment), seed lots and the groups of emergence (GE) were used as the experimental treatments (temperatures of 10 and 20°C). Seedling related parameters including radicle and plumule length and weight were determined. At the seed germination (in the field, split plot experiment) planting date (PD) and seed lot were used as the experimental treatments. At the seedling growth stage (in the field, split split plot experiment) seed lot and group of emergence were also used as the experimental treatments. Seed vigor tests including seed germination and final emergence (FE), and crop yield and yield components including the number of tray per plant (NTP) and grain per tray (NGP), weight of 1000 grains (W1000), harvest index (HI) and grain yield (GY) were determined. In the lab, the seed related parameters were superior in the controlled seeds than the aged seeds, in the large seeds than the small seeds and in SL1 than the other SL’s. There was a negative and highly significant correlation between SL, SS and AA with the EC of the seed leachate as the highest rate of seed germination was resulted by the treatments, which had the least rate of leachate EC. However, GE’s were the functions of environmental conditions including temperature and moisture. In the lab, although at 20°C, GE1 resulted in the highest percentage of seed germination, under the cold conditions GE2 and GE3 significantly increased seed germination percentage, compared with GE1. PD1 and GE1 increased NTP, NGP, W1000 and GY. The lab tests indicated that among the vigor tests, the EC of the leachate and the rate of seed germination and final emergence in the field were highly and significantly correlated with safflower grain yield under field conditions and can be used for the prediction of safflower grain yield.