Studies On Ratooning Characteristics And Its Physiological Basis Of Super Hybrid Rice

Ratooning rice is a special type of cultivated system which suitable for certain ecological districts in southern rice planting area of China. In order to fully utilize ratooning characteristics of super hybrid rice and to explore a feasible way of double high yields both main crop and ratooning rice, a series of studies was carried out from 2006 to 2007, in terms with leading super hybrid rice combinations of Yliangyou No1 (Y58S/9311),Liangyoupeijiu,Yliangyou No8 (Y58S/minghui63),Shanyou63 (CK) as materials. Main results are as follows:1. The ratooning rate of 3 tested super hybrid rice combinations Yliangyou No1,Liangyoupeijiu and Yliangyou No8 were higher than Shanyou63. When the higher stake(40-45cm) was left, the ratooning rate of specific node was in sequence of 2^nd>3^rd>4^th>5^th node, from the top to bottom. Total yield of the main crop and ratoonmg of super hybrid rice were higher than Shanyou63. These super hybrid rice combinations may cultivated as rationing rice in Hunan area.2. The ratooning yield was related positively with the ratooning rate (r=0.9075). The panicles per plant, spikelets per panicle, 1000-grain weight of ratooning rice were related positively with 3 corresponding traits of main crop. The number of effective panicle and spikelets per panicle affected the yield of ratooning rice most. The number of effective panicles and it's contribution to yield was biggest at the 2^nd node, and decreased at the latter node, the 2^nd and 3^rd node contributed 70%-90% to the total ratoon yield.3. Super hybrid rice combinations had higher grain/leaf area rate (for short GAR) comparing to Shanyou63. The ratooning rate was positively related with GAR of main crop. The dry weight (except for old stakes) of ratooning rice was as much as 1/3-1/4 weight of main crop. The yield of ratooning rice was positively related with the dry matter accumulation amount of stem and sheath in main crop ripening stage. The changing trend of soluble sugar contains and starch contains in main cropping nodes was almost the same. The ratooning rate was positively related with the stem node soluble sugar contains and starch contains in ripening stage. The bleeding intensity of Yliangyou No1 and Liangyoupeijiu was obviously stronger than Yliangyou No8 and Shanyou63. Bleeding intensity and bleeding soluble sugar contains were positively related with the ratooning rate and yield of ratooning rice. The amount of MDA in flag leaf was negatively related with which in POD and CAT.4. As to flag leaf in full heading stage, 3 super hybrid rice combinations had the higher net photosynthetic rate, more stomata conductance and lower transpiration rate comparing to Shanyou63. The yield of ratooning rice was positively related with net photosynthetic rate. The amount of chlorophyll contents (SPAD parameters) of function leaves in late stage of main crop was more in super hybrid rice combinations than that in Shanyou63. Furthermore, Yliangyou No1 was stronger tolerant to high temperature stressrelative to Shanyou63, with respect to the photosynthetic characteristics.5. Usually, the proportion of opening anthers and dyeable pollen rate will decrease when come with high temperature stress at heading stage of main crop. However, Yliangyou No1 has much less than Liangyoupeijiu. The trends of growth of ratooning buds were almost the same. The reducing seed-setting rate of Yliangyou No1 was not obvious(6.07%); The protecting enzyme(POD and CAT) activity and number of free Pro the flag leaf had decrease, but the change of MDA was opposite.6. Compared the morphological characteristics of source and sink of ratooning rice and its same-term tasselling main crop. The characteristic of sink was that: the number of ratooning rice effective panicle and the total spikelets per panicle were obviously less than main crop. The total spikelets per panicle was as more as 1/2-1/3 of main crop. The characteristic of source was: The contain of LAI in main crop was 6-7times more than ratooning rice. The photosynthetic rate of ratooning rice was higher than main crop, 3 super hybrid rice combinations showed higher photosynthetic rate than Shanyou63. The characteristic of bleeding was: ratooning rice single plant dry matter amount in ripening stage was as heavy as 25%-35% of main crop. No matter main crop or ratooning crop, the super hybrid combinations exporting percentage of stem and sheaths were higher than Shanyou63. As for source-sink relationship: the rate of grain/leaf area was 2-3 times higher in ratooning rice than in main crop, and the main crop belonged to sink-limited, while the ratooning rice belonged to source-sink interaction , but source-limited was more obvious.7. Compared with Pei'ai64S,Y58S had certain superiority in Nevossia horrida insistance , photosynthesis characteristics and ratooning ability. The rate of grain smut set was lower about 6%, net photosynthetic rate of flag leaf was higher about 14%, and were more tolerant of high temperature, ratooning rate was higher about 14%. And, Y58S had the characteristics of centralized florescence , longer glumales blowing period, and higher stigma exsertion rate.8. In the "main-crop+ratooning rice" cultivated pattern experiment demonstration, Yliangyou No1 showed the superiority of good strain and leaf configuration, stronger ratooning ability, bigger panicle, more spikelets, high seed-setting rate, good rice quality, wide adaptability, high yielding, more economical benefits. Pay attention to sow early, adequate fertilization, strengthen paddy field management, reaping timely, maintain higher stake.