Abstract:

To explore the regulation effect of spraying paclobutrazol at seedling stage on japonica rice in southern Henan Province, in this study, two japonica rice varieties, ‘Xinjing 1787’ and ‘Nanjing 5718’, were used as materials, and different concentrations of paclobutrazol were sprayed through one-leaf and one-heart. Six concentrations (based on active components) were set as M₀ (0 mg/L), M₁ (40 mg/L), M₂ (80 mg/L), M₃ (120 mg/), M₄ (160 mg/L) and M₅ (200 mg/L). The effects of different concentrations of paclobutrazol on seedling quality, dry matter weight, SPAD value and yield composition were evaluated from 2020 to 2021. The results showed that with the increase of paclobutrazol concentration, the seedling height of the two varieties decreased in the two years, the root growth was conducive to tillering, the dry matter accumulation at jointing stage, full heading stage and maturity stage increased first and then decreased, and the SPAD value increased. In terms of yield composition, with the increase of paclobutrazol concentration, except that the number of grains per spike decreased, other indexes increased compared with the control. All indexes of ‘Xinjing 1787’ were the best at M₄, and ‘Nanjing 5718’ had a better performance at M₃. In conclusion, spraying paclobutrazol at appropriate concentrations could improve seedling quality, dry matter weight, SPAD value and yield of japonica rice in southern Henan.

Key words: japonica rice, seedling stage, seedling quality, dry matter weight, SPAD, yield