Daylength extension: a strategy to enhance sucrose metabolism and carbohydrate accumulation for improving spike quality and corm production in Gladiolus (Gladiolus hybridus Hort.).

Daylength extension (DLE) has significant potential to enhance the growth and development of various crops through increased carbohydrate synthesis and metabolism. This study explored the impact of DLE on spike quality, corm production, sucrose metabolism and carbohydrate accumulation of Gladiolus. Plants were subjected to DLE of 2 and 4 h after 30, 40 and 50 days of sprouting. The 2 h of DLE after 50 days of sprouting markedly increased acid invertase, neutral invertase and sucrose synthase activities in leaves by 1.11, 1.88 and 3.53 times and in corms by 1.44, 1.83 and 1.84 times, respectively, compared to natural daylength (NDL). Carbohydrate accumulation improved, with most pronounced effects of DLE after 30 and 50 days of sprouting. The DLE of 2 h also led to early spike development. The DLE of 2 h after 50 days, enhanced spike length (11.54%), weight (14.25%), diameter (11.86%) and floret size (10.98%) compared to NDL. Corm production was significantly higher under 2 h of DLE after 50 days, as corm (97.59 g) and cormel weight per plant (6.33 g), corm diameter (52.82 mm) and number of corms (2.17) and cormels per plant (29.00) increased compared to NDL. Correlation and Principal Component Analysis revealed that improved spike quality and corm production was result of enhanced sucrose enzyme activity, increased carbohydrate accumulation and earlier spike development. Therefore, 2 h of DLE after 30 or 50 days of sprouting could be effective in enhancing corm production and spike quality. Thus, considering economic benefits, employing 2 h of DLE after 50 days of sprouting could be recommended.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-025-01602-5.