Rapid generation advancement protocol of wheat under natural day-length conditions during summer seasons in sub-tropical conditions

Abstract

Developing improved crop cultivars is essential for confronting adverse environmental conditions. Rapid cultivar development requires reducing crop duration through rapid generation advancement (RGA) strategies. Extreme conditions that allow five to six crops annually may not provide plant breeders the opportunity for selection based on phenological traits and also necessitate a well-equipped growth chamber. The present study aimed to develop an RGA protocol under natural daylight during the summer season in sub-tropical conditions, incorporating irrigation, and plant density modulation alongside the chilling treatment of harvested seed. Wheat cultivars HD2932 and HD3086 were grown in 4-inch plastic pots with either one or four seeds per pot. The plants grown at higher density flowered 3 to 4 days earlier than their low-density counterparts. Irrigation was stopped either at 15 or 25 days after anthesis for forced maturity in different sets of plants, and the matured seeds were harvested after 20 days of the last irrigation. Consequently, the seed-to-seed cycle was shortened to 90 to 95 days compared to the regular cropping season (140–150 days). The seeds were subjected to chilling treatment at 4°C prior to sowing, and it was observed that chilling treatment for up to 72 hours can increase germination percentage beyond 90%. The protocol standardized in the current study can help to get two wheat crops with only temperature-controlled chambers in sub-tropical conditions during the summer season. The method can be used intermittently by growing two summer crops and a rabi crop, permitting selection under intermittent moderate RGA and natural growing conditions.