Abstract:

A new hybrid rice Ⅱ Youhang 1 was used to analyze accumulated dry weight, energy fixation and calorific value in early-season rice and its ratooning rice under super high-yield cultivation (SHC) and conventional cultivation (CC) models. The results showed that accumulated dry weight in the plants at mature stage under SHC was 2 220.04 g m^-2 and 1 697.62 g m^-2 for early- season and ratooning rice, respectively, being 1.26 and 1.29 folds higher than that under CC. Calorific value in leaf, grain, sheath and culm of the plant was 14 848.7–18 494.9 J g^-1, 15 810.3–17 438.0 J g^-1, 14 029.1–17 039.6 J g^-1, 14 405.4–17 576.5 J g^-1 under SHC, respectively. The calorific values in leaf and grain were significantly higher than those in culm and sheath, but no significant difference was found under the two cultivation models. The accumulated energy in the plants at mature stage was 35.71 and 26.24 MJ m^-2 under SHC for early season and ratooning rice, respectively, being 27.4% and 29.6% higher than that under CC. The ratio of accumulated energy partitioned into grains was 52.7% for early-season rice under SHC, which was 1.2% higher than that under CC, and for ratooning rice (51.5%), there was no significant difference between the two models. During grain filling, the ratio of energy remobilized from leaf, culm and sheath was 39.7% for early- season rice under SHC, being significantly higher than that under CC (23.1%), and the value was 16.9% for ratooning rice, which was also higher than that under CC (14.7%). It implied that the energy flow in rice community under SHC was much more smoothly than that under CC. In addition, at yellow mature stage, the energy exportation ratio of root was 7.9% under SHC, being obviously lower than that of CC, it was ensured for grain filling and regeneration of ratooning rice, and the energy of grains remobilized from the stubble of ratooning rice was 25.9% apparently, indicating that the grain yield under SHC relied less on the photosynthate in the period of grain filling, which was beneficial to steady and high yield of ratooning rice.

Key words: Rice, Ratoon rice, Cultivation model, Calorific value, Energy