Study On The Effect Of Plant-row Spacing And Stubble Height On Oil Tree Peony Paeonia Ostii ‘Fengdan'

Oil tree peony is a new woody oil crop.In recent years,.Its planting area in China has expanded gradually,but there are still few studies on the oil tree peony cultivation.In this study,oil tree peony paeonia ostii 'FengDan' was used as the test object to investigate the influence of 9 plant-row spacing and 5 different stubble height on growth indexes,photosynthetic characteristics,yield and its component factors.These results can provide theoretical foundations for the optimization of oil tree peony cultivation techniques.The main results are as follows:1.Increasing the plant-row spacing is favorable for the growth of individuals in the horizontal space,which improves the crown width,leaf area,branch numbers and the basal diameter of sprouts,and reduce plant height and sprouts length.The obtained best plant-row spacin is 0.5m×1.0m.The narrower plant-row spacing leads to the increase of plant hight and sprouts length,reducing the number of branches and make them delicate,and displaying a certain degree of excessive growth.2.Paeonia ostii 'Feng Dan' peony shows greatest photosynthetic capacity in May.With the increase of plant-row spacing,the net photosynthetic rate and transpiration rate present much higher.The stomatal conductance and intercellular CO₂ concentration are relatively large,resulting in the improvement of water use efficiency.The leaves possess higher chlorophyll contents and stronger assimilability.Because of the narrow plant-row spacing,interspecific competition increased,and canopy structure was irrational,resulting the photosynthetic capacity,transpiration stress and water use efficiency were low.3.By increasing the plant-row spacing,per plant had more seed production,the pod length was longer and the grain was full.The yield of seed production was not high because of less plant numbers in the same planting area.The narrow plant-row spacing leads to an excessive vegetative growth,which hinder the growth and expansion of fruit,resulting in poor performance of per plant components and lower yield.Therefore,0.5m×0.8m plant-row spacing treatment was adopted to balance the per plant seed production and plant numbers,obtaining the highest yield as 1211.11 kg/hm2.4.The stubble treatment can significantly promote the germination of branches,especially the adventitious bud in root neck.With the decrease of stubble height,the number and length of branches,angle between branches can be increased significantly,but the basal diameter decreased.The stubble height treatments with 3cm and 5cm are are beneficial to the lateral development of plant type,improving the internal ventilation and light transmission condition.Plant height,crown width and leaf area decreased with reduction of stubble height,but the increment during the growth period was more.5.Paeonia ostii 'FengDan' peony diurnal variation of photosynthetic rate showed a "double peak value" trend.With the stubble height decreasing,photosynthetic midday depression drop down gradually,which could maintain a high level at noon.The diurnal variation of transpiration rate increased first and then decreased;the peak rate was reached at noon.The variation trend of stomatal conductance increased with the decreasing of stubble height,the peak data showed at noon;its diurnal variation showed significant correlation with net photosynthetic rate.The diurnal variation of intercellular CO₂ concentration showed "W" type,and showed a negative correlation with net photosynthetic rate,but 3cm and 5cm stubble height treatments were significantly higher than others.The diurnal variation of water use efficiency also showed a "double peak value" trend.The untreated group displayed the lowest efficiency at noon.Therefore,the stubble height of 3cm and 5cm can effectively improve the photosynthetic properties of leaves;change is tiny throughout the day.The content of chlorophyll increased with the decrease of stubble height,and improved the utilization of light energy.