| Abstract: | Low germination and vigor of rice seed associated with dry-seed broadcasting are common problems encountered by rice growers.The objectives of this study were to evaluate the role of potassium nitrate(KNO_3)on the pattern of seed imbibition and to determine the effect of seed priming with KNO_3 on the germination percentage,speed and uniformity of germination in rice seed.Experiment 1 compared the patterns of seed imbibition of six concentrations of KNO_3(0,0.25,0.50,1.00,1.50,and 2.00%)in two rice cultivars-KDML105 and RD15.The results showed that soaking rice seed in KNO_3 at higher concentrations could delay the imbibition time.The higher concentrations of KNO_3 delayed the imbibition time of rice seed and took a longer time to reach the end of phases 1 and 2 compared to the lower concentrations.The patterns of seed imbibition using distilled water of both rice cultivars(KDML105 and RD15)were quite similar,but with different concentrations of KNO_3,the imbibition time taken to reach the end of phases 1 and 2 was slightly postponed in KDML105 suggesting that different rice cultivars may need different imbibition times for soaking seed in the priming process.Experiment 2 evaluated the effects of seed priming with 1.0 and 2.0%KNO_3 at different imbibition times.It was found that priming with 1.0%KNO_3 showed better seed germination than priming with 2.0%KNO_3 and seed priming with 1.0%KNO_3 at the imbibition time of early phase 2(or 28 h for KDML105)improved seed germination and increased both the speed and uniformity of seed germination.The results of this study show promise for the use of priming with 1.0%KNO_3 soaked until early phase 2 of seed imbibition for improving the seed germination and vigor of rice in dry seed broadcasting. |
