Effects of Antimitotic Agents, Temperature and Immersion Time on Chromosome Doubling Efficiency in Supersweet Corn ( Zea mays L

ABSTRACT

Doubled haploid technology accelerates the development of fully homozygous maize lines compared with conventional selfing. However, specific protocols for supersweet corn ( Zea mays L . var. saccharata ), particularly regarding immersion time in antimitotic solutions and temperature during chromosome doubling, remain poorly defined. This study investigated haploid induction rates in supersweet corn with a tropicalised haploid inducer hybrid and evaluated the effects of temperature and immersion time across three antimitotic solutions in an adapted newly germinated seeds method for chromosome doubling. Survival rate was assessed in diploid seeds immersed in water at 0°C, 17°C and 25°C and in haploid seeds treated with water at 0°C and 17°C, as well as with colchicine, pronamide and amiprophos‐methyl combined with pronamide, at 17°C under different immersion durations. Chromosome doubling efficiency of putative haploid was compared among the newly germinated seed treatments and with the root immersion method in colchicine. The tropical inducer hybrid showed an average haploid induction rate of 14.6%. Temperature and exposure time strongly affected survival and overall protocol feasibility, and 17°C emerged as the most suitable temperature by enabling longer exposure to antimitotic agents while maintaining higher survival. Treatments with 10 h in pronamide and 12 h in amiprophos‐methyl plus pronamide increased chromosome doubling but caused high mortality, indicating that shorter exposures are more suitable. Water treatment at 0°C did not improve chromosome doubling efficiency. These results demonstrate that herbicide‐based immersion of newly germinated seeds at 17°C is a promising alternative for chromosome doubling in tropical supersweet corn.