Abstract:
The purpose of this research was to improve early hybrids maize suitable for Upper Northern Region Area 2 (Chiang Rai, Phayao, Phrae and Nan). Testing hybrids maize varieties have performed under the University of Phayao Maize Improvement Project. Ninety-one lines were directly crossed with four testers. Finally, one hundred thirty-seven hybrids were received. Then, the preliminary yield trial was conducted. After that, the ten promising hybrids were chosen, viz., UPSX205 UPSX223 UPSX227 UPSX245 UPSX253 UPSX269 UPSX305 UPSX319 UPSX320 and UPSX491. These hybrids were cultivated in 4 provinces, Chiang Rai, Phayao, Phare and Nan, from January to May 2019,. In the experimental design, the trial was conducted in RCBD with 3 replications. The agronomic character results, tasselling and silking averaged 74 and 75 d, respectively. Meanwhile, plant and ear heights were different averaging 208 and 107 cm, respectively. For grain yield performance, the top 3 hybrids were UPSX223 UPSX205 and UPSX491 giving yield about 2,043 1,880 and 1,836 kg per rai, respectively. While check varieties, NSX052014 NSX152011 and Pac139 gave yield about 1,737 1,535 and 1,932, respectively. Therefore, these new hybrids have suitable to support farmers growing in Chiang Rai, Phayao, Phare and Nan provinces.