Effects Of Different Cultivation Methods On Rice Yield And Population Characteristics

To explore the effects of different types of machine planting on rice population characteristics and yield.Field experiments were carried out with cultivar Yongyou538 and cultivar Zhendao 18 at Guo He modern agriculture demonstration area（117.23°E,31.48°N）in 2015,four treatments including plant pot seeding pendulum（Ppp）,blanket plug seeding machine（7）（Bpm 7,7-inch row spacing）,half a pot seeding by machine（Hpm）,and blanket plug seeding machine（Bpm 9,9-inch row spacing）were investigated in order to study its effects on the characteristics of rice seedling quality,dry matter accumulation and distribution,photosynthetic physiological characteristics,lodging resistance,plant type and canopy structure,population balance,and yield.The main results are described as follows:1.There existed significant difference among four treatments for grain yield（p<0.05）.The trend of yield were expressed as Ppp>Bpm（7）>Hpm>Bpm（9）,which the Ppp treatment increased by 4.64⁷.50%,8.43²0.86%,and 17.16²2.11%compared with Bpm（7）,Hpm,and Bpm（9）treatments,respectively.For yield components parameters,the setting rate and grain weight of cultivar Yongyou 538 had a little difference,also,the rice grains per spike and grain weight of cultivar Zhendao 18were little amplitude of variation among treatments.The effective panicles in Bpm（9）treatment were the highest across cultivars,but small storage capacities such as panicles and spikelets sizes were found in Bpm（9）treatment because the emerging time both tillering starting and maximum population were delayed for two cultivars.Therefore,greater size of panicles could be the key guarantee obtaining high yield for mechanical planting rice.2.The rice seedling quality before transplanting in Ppp treatment were the greatest,and then followed by Bpm（9）,Bpm（7）,and Hpm treatments across two cultivars.Among trem,the plants height of cultivar Yongyou 538 increased by33.97%in Ppp treatment when compared with Hpm treatment,moreover,the number of green leaves were higher than 1.8 leaf number per plant in Ppp treatment than in Hpm treatment,menwhile,the number of yellow leaves were less than 0.75 tablets per plant considering both cultivars.The aboveground biomass in Ppp treatment was greater 96.37%than that in Hpm treatment,but there was no significant difference（p<0.05）for root length among treatments for two cultivars.After transplanting,the seedling quality were also performance a similar tendency among treatment of two varieties,which meaning the Ppp treatment show the greater quality than others.The transplanted seedlings could quickly produce 0.6-1.2 tillers after transplanting 6 days in Ppp treatment,it was higher 22.22%-83.33%than other three ways.And the number of new root was up 33.33%-89.47%compared with the other three planting machine mode（Zhendao 18 was 107.69%to 125%）after transplanting 2 days.Generally,the Ppp treatment had a benefit to improve rice yields because of good seedling quality.3.Dry matter in Ppp treatment were the highest compared with the another three treatments.Three tillers could be produced after the 8^thday after transplanting.The net photosynthetic rate（Pn）observed at booting stage were 17.36μmol·m^-2·s^-11 in Ppp treatment,were 16.46μmol·m^-2·s^-11 in Bpm（7）treatment,were 14.21μmol·m^-2·s^-11 in Hpm（7）treatment,and 16.56μmol·m^-2·s^-1in Bpm（9）treatment.SPAD value were higher 3%than the other treatments.Leaf area index（LAI）were 10.14 and 8.87 at booting and heading stages in Ppp treatment,respectively,which perform high photosynthetic produce ability and could provide adequate post-reproductive assimilates growth in order to achieve high yield.Abovegroud biomass at heading stage increased by 17.69%in Ppp treatment compared with others for cultivar Yongyou 538,and by 11%in Ppp treatment compared with others for cultivar Zhendao18.The lower yield in Hpm and Bpm treatments could be relevant to less pre-dry matter accumulation,insufficient photosynthetic products,and lower seetting rate when compared with Ppp treatment.4.The height of the four leaves,which were the first leaf from canopy top,the second leaf from canopy top,the third leaf from canopy top,and the fourth leaf from canopy top,was significantly lower in Ppp than in the other treatments of Yongyou538.The performance of the height of the three leaves from the first leaf of canopy top to the third leaf of canopy top was sequence with Bpm（7）>Ppp>Hpm>Bpm（9）for cultivar Zhendao 18.The height and relative height of the three leaf from canopy top of cultivar Yongyou 538 were negatively correlated with yield,but the correlation was not significant（p>0.05）,and relative position and height of three leaf from canopy top of cultivar Zhendao 18 was significantly negatively correlated with panicle dry weight(r_TLRHCV=-0.974*,r _earar CV=-0.956*).The CV in Ppp treatment was minimum across both cultivars,meaning Ppp had the greatest uniformity.Yongyou 538 inverse fourth leaf long CV only 1.51,while Yongyou 538 Hpm and Bpm（9）down four leaf height CV was poor,which reached 11.55 and 10.49,Zhendao 18 had a similartendency,which was consistent with production trends,showing the higher uniformity is favor the formation of higher yield.