Obtention of tetraploids in bottle gourd (Lagenaria siceraria) and citron (Citrullus lanatus var. citroides) by shoot immersion method using different colchicine doses and application times

The study to obtain tetraploid plants from bottle gourd (Lagenaria siceraria) and citron (Citrullus lanatus var. citroides.) by using shoot immersion colchicine application method in in vivo condition was conducted at experimental area of the Department of Horticulture, University of Cukurova in Turkey. The aim was to determine the best colchicine dose and time in obtaining tetraploids to be used as rootstocks in watermelon grafting. Colchicine was applied 7 weeks after transplanting to all genotypes. For both genotypes, plants were treated with 2 doses of colchicine (0.5 and 1.0%) at three different durations (1, 2 and 4 h). Colchicine dose of 0.5% resulted in high induction rate of tetraploids at 1 and 2 h in Lagenaria. Immersing bottle gourd plant shoot tips into 1% colchicine resulted in burning of the growing shoot in all times. Colchicine application induced higher rate of tetraploids in citron than in bottle gourd. Immersing the tip of citron shoot into 0.5% colchicine for 1 h resulted with highest induction rate of tetraploids. Immersing growing shoots of citron into 1% colchicine dose resulted into induction rate of 33.33% for 1 h and 50.00% for 2 h. Citron has high resistance to 1% colchicine dose when immersed into solution for up to 2 h. Immersing the growing shoot tip into colchicine for 4 h caused burning. Based on the results of our study, colchicine application by shoot immersion method is best when applied at low dose in a short time in bottle gourd and at high dose in a short time in citron.