Improvement of Inpari 30 and Situ Bagendit rice varieties for tolerance to drought through spike-stalk injection method

Extreme climate change requires rice varieties adaptable to drought condition. Adaptation will play an important role in ensuring the sustainability of food security. This research aimed to improve drought tolerance of Inpari 30 and Situ Bagendit varieties through Spike-Stalk Injection Method (SIM). DNAs from several plant species, such as rice (cv. Cabacu), grasses (Echinochloa crusgalli/E. colona, elephant grass/Pennisetum purpureum, Bothriochloa pertusa, Cenchrus echinatus, Sorghum nitidum, Ischamemum timorensis and Guinea grass), sugarcane, wild rice (Oryza nivara), maize and sorghum were injected to tillers of cultivar Inpari 30 and Situ Bagendit. The first set of M1 Situ Bagendit-SIM and M1 Inpari 30-SIM seeds were treated with 20% of PEG 8000 solution for 10 days. Some of the well germinated seeds were planted in pots and maintained untill harvest. The selected M2 Situ Bagendit-SIM and M2 Inpari 30-SIM and the second set of M1 Situ Bagendit-SIM and M1 Inpari 30-SIM seeds were planted at Muara Experimental Station, Bogor (West Java). The result of PEG 8000 assay showed that M1 Situ Bagendit-SIM-elephant grass, sugarcane and O. nivara had significantly longer radicle length and higher fresh weight compared to Situ Bagendit, while M1 Inpari 30-SIM-sugarcane, sorghum and elephant grass had significantly longer radicle and plumule length, and higher radicle weight compared to Inpari 30. Field trial showed that the mutant lines of Situ Bagendit-SIM performed better than those of Inpari 30-SIM. The grain weight of M1 Situ Bagendit-SIM-Cabacu, jajagoan grass, maize, sugarcane, O. nivara and B. pertusa, and M2 Situ Bagendit-SIM-O. nivara and elephant grass were higher than that of Situ Bagendit. The grain weight of M1 Inpari 30-SIM-jajagoan grass was also higher than that of Inpari 30. Therefore, SIM could be an alternative way to develop genetic variation of rice plant.