Differences In Leaf Age Process Of Different Types Of Rice And Their Responses To Nitrogen

Rice(Oryza sativa L.)is one of the most essential crops in the world.Advances in agronomic crop management such as new varieties,yield improvement,are necessary to meet the world’s growing population demand.Leaf age model is very important since we can predict the occurrence date of different leaf positions,simulate the time of organ formation due to the better co-Extension relationship between leaf age,branch,stem,root and spike.In rice,number of main stem leaf at the terminal spikelet stage is strongly related to final leaf number and many studies have shown that most developmental events until anthesis can be related to the appearance of main stem leaves.It has been reported that Hybrid Indica is more likely to respond positively to nitrogen applications than japonica cultivars,thought in this present report Hybrid Indica presented less leaf number compared to Japonica cultivars however Hybrid Indica had a clear pattern and uniformity as a response to nitrogen rates as opposed to Japonica cultivars.The relationship between leaf number,leaf appearance rate and Rice yield and yield components was discussed and due to these two rice types genetic differences there was a vast discrepancy of results leading to no clear conclusion.The leaf number of Hybrid Indica and Japonica cultivars from transplant up to panicle initiation were evaluated and their response to three different levels of nitrogen applications.The relationship between leaf number,LAR and yield and yield components were studied.The main findings are as follows:1 The amount of nitrogen significantly influenced the Hybrid Indica cultivars LN,it was directly proportional to nitrogen rate in the first year N0=15.5,N150=15.7,N300=15.9 and the second year N0=15.9 N150=16.3 N300=16.5 with a significant difference in both years,on the other hand,the Japonica rice cultivars were not as responsive to Nitrogen as Hybrid Indica’s were,Japonica rice in both years N0=16.2,N150=16,N300=16.8 and N0=16.4,N150=16.6,N300=16.5 for 2017 and 2018 respectively,with a significant difference in the first year only at N300 and there was no significant difference in the second year.The LAR had decreased with the increase of nitrogen rates in both years N0=41.2,N150=39.8,N300=39.7 and N0=44 N150=43,N300=42.4 for 2017 and 2018 respectively.There was no significant difference between Hybrid Indica(4.3/4.2)and Japonica rice type(4.2/4.4).The DTP revealed to be significantly affected by different Nitrogen rates reducing its time duration with high dosages of nitrogen N0=41.2,N150=39.8,N300=39.7 and N0=44,N150=43,N300=42.4 for 2017 and 2018 respectively.The LN varies greatly among varieties.Nitrogen rates had a significant effect on LN,but the effect value was less than 0.4 leaves between both years.Nitrogen reduces LAR and shortens DTP.2 There are several different factors influencing the rice yield and yield components and the present experiment aimed to disclose the LN and LAR relationship with yield and yield components.This study was conducted to evaluate the relationship between two rice type’ s(Hybrid Indica and Japonica cultivars)with LN and LAR.A split plot experiment design with three replications was conducted in the research field of Danyang District,Jiangsu Province,in China from 2017 to 2018 both rice’s growing seasons.Hybrid Indica cultivars revealed to be more correlated with LN than Japonica cultivars.Yield and spike No/m2 were positively correlated at 0.05 and 0.01 respectively and negatively correlated with LAR and Japonica cultivars spike and field yield were negatively correlated at 0.05 level and with no correlation with LAR.DW-HS,and DW-MS were positively correlated with LN at 0.01 and 0.05 respectively and negatively correlated with LAR in the second year.