Effects Of Half-period Dry Management Of Middle Hybrid Rice On The Growth And Development Of Its Ratooning Rice

Rice is the most important food crop in China and it is also the biggest water-consumer among all crops.The water shortage is an important limiting factor in rice production in China.The use of water-saving cultivation technology is very important for the development of rice production.Half-period dry management is a new water-saving cultivation model designed according to the climate of Yangtze Basin. Ratooning rice following middle rice has advatages of saving the cost of seeds,labor time and fertilizer.Raising ratooning rice are currently practiced in many regions of China.Investigation was made on the effect of half-period dry management of middle hybrid rice on the growth and development of its ratooning rice in order to explore its potential utilization.Four hybrid rice varieties(Shanyou 63,Yangliangyou No.6, Eryou838,Jingyou63) were used in field experiment and two of them(Shanyou 63, Yangliangyou No.6) were also used in pot experiment under a plastic greenhouse.During the main crop season two treaments were adopted with half-period dry management treatment compared with traditional water management.While traditional water management was applied to all the ratooning rice.The main results are as follows:1.Half-period dry management is effective in saving irrigation water.The results of pot experiment indicated that half-period dry management saved 40.20%irrigation water as compared to the control,and the average water productive efficiency of the two hybrids was improved by 42.89%.2.Field experiment showed that the average rice yield resulted from half-period dry management was slightly higher than that of the control,but different varieties differed in their yeild performance.The results of the field experiment indicated that the average yield of main crop,ratooning rice and the total yield were 3.95%,3.77%and 3.85% higher than that of the control.The yield of main crop,Jingyou63 Shanyou 63 and Eryou838 increased by 11.33%,5.84%and 1.54%,while ratooning increased 11.86%, 14.33%and 2.42%respectively.But the yield of the main crop and ratooning of Yangliangyou No.6 decreased by 2.9%and 13.53%. The pot experiment showed that the average yield of main crop and ratooning rice were 4.21%and 8.15%higher than that of the control.The average yield of main crop and ratooning rice of Shanyou 63's increased 25.38%and 3.09%respectively.But the yield of the main crop of Yangliangyou No.6 decreased by 18.66%,while ratooning increased by 11.10%.3.The grain quality traits of the main crop and ratooning rice under half-period dry management conditions varied in different degree as compared to that of the control.For the main crop rice,percentage of brown rice droped by 0.36%,percentage of milled rice increased by 0.05%,percentage of head rice increased by 1.3%,chalkness ratio droped by 1%;and for the ratooning rice,the percentage of brown rice increased by 0.39%, percentage of milled rice increased by 0.27%,percentage of head rice decreased by 0.15%,but chalkiness ratio increased by 2.01%.4.The Agronomic characteristics of the main crop and ratooning rice under half-period dry management conditions varied in different degree as compared to that of the control.Under the half—period dry management,There is no apparent different in growth duration between the rice under the half—period dry management and that of the control.The height and panicle length of the main crop rice decreased by 6.5 cm and 1.36 cm respectively.And the height of ratooning decreased 1.66 cm,but the panicle length of ratooning increased 2.17 cm.5.The leaf area and the grain-leaf ratio of main crop and ratooning under half-period dry management increased 0.18 and 0.81 respectively.The maximum tillering number of the main crop increased 0.9 per plant,but the percentage of effective panicles decreased by 1.4%.The length of the of dormant bud of main crop and its regeneration rate tended to increase under half—period dry management.