| With three different panicle types of japonica rice cultivars Tonghe833(curved panicle),Tiejing7(erect panicle),Shendao506(semi-erect panicle type)as entries,the effect of five row distances(15.0cm,17.5cm,20.0cm,22.5cm,25.0cm)on yield as well as,photosynthetic characteristics and lodging traits.With 13 japonica rice cultivars in Northeast China were used as entries,compared the yield formation,photosynthetic characteristics and material accumulation of different cultivars.The results were showed as follows:1.Comparison of yield,photosynthetic characteristics and matter accumulation of different japonica rice cultivars under drill seedingThe yield trends of thirteen rice cultivars in 2015 and 2016 were basically the same,but,generally,the latter was higher than the former.The yield order in 2015:Jinongda878>Shendao171>Shendao403>Shendao422>Shendao632>Shendao305>Tiejing7>Shendao529>Jida6>Pingan13>Yuanfeng6>Shendao631>Shendaol59,and the highest yield was more than the minimum yield by 22.1%.The yield order in 2016:Jinongda878>Shendao171>Shendao422>Shendao403>Shendao632>Shendao305>Tiejing7>Shendao529>Shendao159>Jida6>Pingan13>Yuanfeng6>Shendao631,and the highest yield was more than the minimum yield by 24.9%.The spikelets per panicle and full grains per panicle were significantly correlated with yield.In this thirteen cultivars,the comprehensive traits of Jinongda878,Shendao171,Shendao403,and Shendao422 were better generally,because the four cultivars had the higher productive panicle number.Shendao171 with high tiller number at jointing stag),the above three cultivars had higher productive panicle rate.Furthermore,the four cultivars also had" excellent individuals physiological characteristics including higher SPAD,net photosynthetic rate,LAI etc.During the late growth period from heading to maturity,the four cultivars had higher phase dry matter accumulation,photosynthetic potential net assimilation.Above knowable,higher productive panicle number per unit area,more production and distribution of photosynthetic substances,and the coordinated development of multiple factors are the key to the high yield of drill seeding rice.2.Effects of row distances on yield and its components of different panicle type rice cultivarsWith the increase of row distances the yield of Tonghe833,Tiejing7 and Shendao506 first increased and then decreased.The row distances of Tonghe833,Tiejing7 and Shendao506 for the highest yield were 22.5cm,17.5cm and 20.0cm,10262.1kg/hm2.11037.2kg/hm2、101a9.akg/nm2,respectively,ind yields of above treatments were significantly higher than those of other treatments.The row distances of Tonghe833,Tiejing7 and Shendao506 for the lowest yield were 15.0cm,25.0cm,15.0 and 25.0cm,9514.9kg/hm2.9597.6 kg/hm2.9528.7 kg/hrrm2,respectively;The productive panicles per unit area and seed setting rate also performed worse.In the highest yield treatment of three cultivars,the productive panicles,seed setting rate were also highest,and significantly higher than those of other treatments;spikelets per panicle,full grains per panicle and 1000-seed weight were not significant among treatments.In the same sowing rate,different panicle type cultivars should cooperate with certain row distances,which could coordinate the competition in the row and between rows,benefit the individual plant growth,insure the more productive panicle number and higher seed setting rate,and construct reasonable population structure so as to achieve the goal of high yield.3.Effects of row distances on photosynthetic characteristics of different panicle type rice cultivarsDifferent panicle type cultivars showed different population structure under different row distances.The erect panicle type cultivar Tiejing7 was suitable for smaller row distance (17.5cm),the curved panicle type cultivar Tonghe833for larger row distance(22.5cm)and the semi-erect Shendao506 for medium row distance(20.0cm).The seedling numbers per unit area had no significant differences among the treatments for three cultivars at 3-leaf stage,while the productive panicle numbers per unit area among treatments were significantly different;Tonghe833 in larger,Tiejing7 in smaller and Shendao506 in medium row distance has better phase dry matter accumulation which was consistent with yield increasing trends;the net photosynthetic rate increased first and then decreased with different row distances for three cultivars.The highest of photosynthetic rate values of both flag leaf and reciprocalsecond leaf of Tonghe833,Tiejing7 and Shendao506 appeared in 22.5cm,17.5cm and 20.0cm row distances,respectively.4.Effects of row distances on lodging characteristics of different panicle type rice cultivarsFor the three cultivars in this study,the order of lodging index was curved panicle type>semi-erect panicle type>erect panicle type,and the lodging index at dough stage was bigger than that at milk stage.The breaking resistance and bending moment all showed N1>N2>N3 for three cultivars at milk and dough stages;lodging index showed N3>N2>Nl.At milk and dough stages,for Tonghe833 the highest value of breaking resistance and bending moment appeared as the row distance was 22.5cm,and the highest value of lodging index appeared at 15.0cm row distance,and the lodging index was decreased with row distance increase.For Tiejing7 the highest value of breaking resistance and bending moment were obtained when the row distance was 17.5cm,the lodging index was the highest when the row distance was the largest,and some correlations reached significant level.For Shendao506 the highest value of breaking resistance and bending moment were found at 20.0cm row distance,but the highest lodging index was found at milk stage with 15.0cm row distance and at dough stage with 25.0cm row distance.In this experiment,increasing row distance of curved panicle type rice cultivars and decreasing row distance of erect panicle type cultivars,reducing plant height,reducing plant weight while keeping higher panicle weight,lowering plant barycenter,and increasing breaking resistance could reduce the probability of lodging. |
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