| Different fertilizing amount and planting density are important factors affecting the water consumption and growth of crops.With the progress of science technology and the development of agricultural modernization,the technology of computer three-dimensional point cloud simulation of crop plant morphology to extract crop related parameters has become increasingly mature.In order to obtain the summer maize water consumption and the growth condition quickly and accurately,planting summer maize in 2018-2019,using the eddy covariance data and correction of double crop coefficient theory model to estimate the summer maize evaporation(ETc),combined with 3 d scanner for summer maize density of different typical reproductive period of three-dimensional point cloud data,studies effects of different fertilizer and planting density on water consumption,water use efficiency and yield of summer maize,and analysis the relationship between planting density and the 3 d point cloud model.The optimal fertilizing amount and optimal density of summer maize were selected,and the main conclusions were as follows:(1)The effects of fertilization amount on Tc transpiration of summer maize were different at each growth stage.At the initial growth stage,the effect of fertilizer amount on Tc was not obvious.At the middle growth stage,the amount of fertilizer applied was large,and the Tc was relatively large.Tc and E of summer maize showed an overall downward trend in the late growth period,and Tc and E had mutual influence on ETc of summer maize.The growth,yield and water use efficiency of summer maize were affected by different fertilization amount(calculated by weight of 100 grains)(P < 0.01).Too much or too little fertilizer can reduce maize yield.Proper fertilization can increase the proportion of Tc in ETc and reduce the consumption of E,so that water consumption can be distributed in the direction of increasing crop yield.(2)The Tc of summer maize transpiration at different planting densities varied in each growth stage,but the overall trend was higher in the middle growth stage than in the early growth stage and the late growth stage.The total evapotranspiration of summer maize during the whole growth period did not increase with the increase of density.The effect of different planting density on the number of ears,grains and ear length of summer maize was lower.The effects of different planting densities on ear thickness,bald tip length,hundred-grain weight and yield were significant(P<0.01).Under different planting densities,combining the economic benefit analysis of water-saving irrigation principle,water use efficiency and yield composition,D3 treatment of summer maize can achieve the best effect.Therefore,it is a key measure to increase water use efficiency and allocate water consumption to increase crop yield by reasonably dense planting and optimal fertilizer application.(3)Parameters(plant height,leaf area,stem thickness)were extracted from the three-dimensional point cloud model of summer maize to study the effects of different planting densities on the growth and development of crop plants.The results showed that the planting density is dense or sparse,which is not conducive to the growth and development of summer maize.It can be seen from the three-dimensional point cloud model that the phenotypic growth of maize plants is optimal under the reasonable planting density.The ETc of summer maize was respectively fitted with the plant type parameters extracted from 3d point cloud data in a single regression linear model,and the LAI was positively correlated with ETc and Tc.The fitting effect between plant height and plant type parameters and evapotranspiration was poor,indicating that the leaf area index in summer maize plant type parameters had a great influence on evapotranspiration and transpiration.The parameters such as plant height and stem diameter had little effect on evapotranspiration of summer maize. |
