Analysis Of Heterosis Relationships Among Tropical Maize Populations And Identification Of Populations Useful For Improving Silage Corn

Tropical and subtropical maize germplasms are good materials for breeding silage corns due totheir fine qualities such as strong disease resistance, eurytopicity, adaptitude, dark green leaves, longperiod of keeping leaves green, strong roots and stiff stalk, etc.. Therefore, increasing attention has beenpaid to them in recent years. However, due to photoperiod sensitivity, most tropical and subtropicalgermplasm sources generate delayed flowering, taller plant, susceptible to lodging, incoordination ofmale and female flowers, and poor seed setting rate, resulting difficult to make use of them directly.Firstly, the study was to evaluate utilization potential of eight tropical and two Chinese maizepopulations as silage corn in Huanggang city, Hubei province. The results showed that: Cpop.26,Cpop.28, Cpop.25, Cpop.24and Cpop.11had higher dry matter; Cpop.25, Cpop.26and Cpop.24hadlonger period of green leaves; Csyn5, Csyn7, Cpop.11, Cpop.22, Cpop.23and Cpop.28had strongerlodging resistance; Cpop.27and Cpop.11had lower neutral detergent fiber(NDF) content; Csyn7,Cpop.23and Cpop.25had lower acidic detergent fiber (ADF) content; Csyn5, Cpop.22, Csyn7andCpop.11had higher crude protein (CP) content. In short, Cpop.11could be directly used as silage corns,other populations could be used to improve specific quality of silage corn.Secondly, five tropical maize populations were crossed to two Chinese populations Csyn5andCsyn7representing Sipingtou and PA, respectively, according to the NCII design for evaluatingcombining ability and heterosis effects between tropical populations and domestic germpalsm inHuanggang city, Hubei province. A and B represented Csyn5and Csyn7, respectively; C, D, E, F, andG represented Cpop.24, Cpop.25, Cpop.26, Cpop.27and Cpop.28, respectively. Combination of lettersrepresented crosses respectively. The results showed that: Cpop.25had higher general combining ability(GCA) for grain yield; Cpop.26, Cpop.24and Cpop.27had higher GCA effect for keeping leaves green;Cpop.26and Cpop.24had higher GCA in lodging resistance; Cpop.28and Cpop.27had higher GCAeffect for CP; Cpop.27and Cpop.28had higher GCA effect for low NDF; Cpop.27, Cpop.24andCpop.28had higher GCA effect for ADF; Chinese populations Csyn5had GCA effect for high grainyield, lodging resistance and high CP; Csyn7had higher GCA for keeping leaves green, low NDF andlow ADF. These populations could be used for silage corn hybird breeding with high heterosis. Amongthe ten crosses, BE, AG, AD, BF and AC had better specific combining ability (SCA) for dry matter; BC,AD, AE, AG and BF had better SCA effect for keeping leaves green; AD, AF, BG, BC and AE had betterSCA effect for lodging resistance; AG, AE, BD, AC and BF had better SCA effect for NDF; AG, BE, BF,BD and AC had better SCA effect for ADF; AE, BG, BC, BD and AF had better SCA effect for CP.The results showed that: there was a significant positive correlation between the number of greenleaves and the NDF and ADF, thus fine silage corns may be selected through high number of greenleave. The study also found a significant positive correlation between NDF and ADF, suggesting thequality traits (NDF and ADF) could be improved together by GCA effects or phenotypic selection.