The underlying mechanism of variety–water–nitrogen–stubble damage interactions on yield formation in ratoon rice with low stubble height under mechanized harvesting

Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary bud sprouting and yield formation in ratoon rice. This study used widely recommended conventional rice Jiafuzhan and hybrid rice Yongyou 2640 as the test materials to conduct a four-factor block design field experiment in a greenhouse of the experimental farm of Fujian Agricultural and Forestry University, China from 2018 to 2019.The treatments included fertilization and no fertilization, alternate wetting and drying irrigation and continuous water flooding irrigation, and plots with and without artificial crushing damage on the rice stubble. At the same time, a 13C stable isotope in-situ detection technology was used to fertilize the pot experiment. The results showed significant interactions among varieties, water management, nitrogen application and stubble status.Relative to the long-term water flooding treatment, the treatment with sequential application of nitrogen fertilizer coupled with moderate field drought for root-vigor and tiller promotion before and after harvesting of the main crop, significantly improved the effective tillers from low position nodes. This in turn increased the effective panicles per plant and grains per panicle by reducing the influence of artificial crushing damage on rice stubble and achieving a high yield of the regenerated rice. Furthermore, the partitioning of 13C assimilates to the residual stubble and its axillary buds were significantly improved at the mature stage of the main crop, while the translocation rate to roots and rhizosphere soil was reduced at the later growth stage of ratooning season rice. This was triggered by the metabolism of hormones and polyamines at the stem base regulated by the interaction of water and fertilizer at this time. We therefore suggest that to achieve a high yield of ratoon rice with low stubble height under mechanized harvesting, the timely application of nitrogen fertilizer is fundamental,coupled with moderate field drying for root-vigor preservation and tiller promotion before and after the mechanical harvesting of the main crop.

Effects of Planting Density on Yield and Mechanical Harvesting Loss Rate of Brassica napus L.

[Objective] This study aimed to explore agronomical measures to reduce the mechanical harvesting loss of rapeseed. [Method] Two rapeseed cultivars, Ningza 19 and Ningza 21, with certain pod-cracking resistance, were employed in field experiments. The two-factor split plot design and randomized complete block design were adopted. The rapeseed seeds were directly sowed with four different seeding rates （1.50, 2.25, 3.00 and 3.75 kg/hm2）. A total of four treatments were designed （112 500, 225 000, 337 500 and 450 000 plants/hm2）. After ripe, the rapeseed was harvested with harvester. Then the yield and harvesting loss rate were determined. [Result] When the planting density ranged from 112 500 to 450 000 plants/hm2, the mechanical harvesting loss rate was decreased with the increase of planting density （Ningza 19, 7.54%-4.01%; Ningza 21, 7.19%-3.81%）. The total loss rates were all below 5% for the high plant densities, 337 500 and 450 000 plants/hm2. High planting density had certain regulating effects on plant type of rapeseed, including reducing plant height, reducing biomass per plant, reducing branch pod numbers per plant, weakening crossing and tangling among stems and improving ripening uniformity of pods. All the changes above were all conducive to reducing mechanical harvesting loss. In addition, the test results showed after the pods grew to maturity, especially when pods were yellow and the moisture content in grains was reduced to 11%, the mechanical harvesting loss only accounted for about 1% of the total field loss. In addition, the shattering loss, caused by mild col- lision, represented more than 90%, and the cleaning loss, occurred during the threshing and cleaning process, represented 4%-8% of the total field loss. The un- harvesting loss accounted for approximately 1% of the total loss. The shattering loss is closely related to cultivar characteristics, planting density, production level and other agronomic factors. The cleaning loss is determined by properties of harvesting machines. The unharvesting loss depends on mechanical properties ad skills of workers or farmers who drive harvesting machines. [Conclusion] In order to reduce mechanical harvesting loss, the rapeseed production should be improved from the perspectives of agricultural machinery and agronomic measures.

Exploring the impact of high density planting system and deficit irrigation in cotton(Gossypium hirsutum L.):a comprehensive review

Lessons learned from past experiences push for an alternate way of crop production.In India,adopting high density planting system(HDPS)to boost cotton yield is becoming a growing trend.HDPS has recently been considered a replacement for the current Indian production system.It is also suitable for mechanical harvesting,which reducing labour costs,increasing input use efficiency,timely harvesting timely,maintaining cotton quality,and offering the potential to increase productivity and profitability.This technology has become widespread in globally cotton growing regions.Water management is critical for the success of high density cotton planting.Due to the problem of freshwater availability,more crops should be produced per drop of water.In the high-density planting system,optimum water application is essential to control excessive vegetative growth and improve the translocation of photoassimilates to reproductive organs.Deficit irrigation is a tool to save water without compromising yield.At the same time,it consumes less water than the normal evapotranspiration of crops.This review comprehensively documents the importance of growing cotton under a high-density planting system with deficit irrigation.Based on the current research and combined with cotton production reality,this review discusses the application and future development of deficit irrigation,which may provide theoretical guidance for the sustainable advancement of cotton planting systems.

Screening and Breeding of Sweetpotato Varieties Suitable for Mechanical Harvesting

The lower degree of mechanical harvesting is a bottleneck hindering the healthy development of sweetpotato industry in China, while the mismatching be- tween agricultural machinery and agronomy is one of the main factors for poor me- chani.cal harvesting. In this study, total five sweetpotato varieties were selected, and the effects of different shapes and sizes on mechanical harvesting of sweetpotato were investigated. The results showed that the breakage rate of Xuzishu 5 was lowest, so it is more suitable for mechanical harvesting in field. At the same time, the correlations between sweetpotato shape, breakage rate and exposure rate were analyzed. It was found that there was a significant linear correlation between sweet- potato shape and breakage rate （P〈0.01）; the higher the flat rate is, the higher the breakage rate is; and sweetpotato shape had no significant effect on exposure rate. Therefore, tuberous root with lower flat rate, as well as better agronomic characters should be selected in the breeding process of new sweetpotato varieties.

Effects of Mechanical Harvesting on Sugarcane Stubble Quality and Growth of Ratoon

The experiment was conducted with the traditional manual harvesting and mechanical harvesting of sugarcane,to compare the effects of different harvesting method on the sugarcane stubble quality and the growth of ratoon.The experimental results are as follows.(i) The stubble height and breaking stubble rate of mechanical harvesting was significantly higher than manual harvesting,the stubble height of lodging species and difficult defoliation species increased in mechanical harvesting condition.Varieties with higher levels of fiber had lower rate of broken stubble.(ii) The effects of mechanical harvesting on germination of next year ratoon were quite different due to different varieties,indicating that the better perennial species have less impact than the poor perennial species.(iii) Compared with manual harvesting,mechanical harvesting had slightly higher plant height and single-stem weight and less effective stems number,the difference of cane yield was not significant,but sucrose content increased 0.53%.(iv) Mechanical harvesting combining with leaves crushing could reduce the impact on the germination of ratoon,improve the single-stem weight and increase the effective number of stems.

Influence of Cutting Stages and Sugarcane Varieties on Sucrose Content in a Brazilian Power Plant with Mechanized Harvesting

This study, carried out in a sugarcane mill located in the center-west region of Sao Paulo state, Brazil, aimed to evaluate the association of sucrose amount （POL%） with sugarcane varieties and cutting stages using mechanized harvesting. A two-way analysis of variance （ANOVA）, complemented by multiple comparison tests, was used in order to identify the effects of variety types and cutting stages on the sugarcane POL% content. An interaction between the sugarcane variety and the cutting stage was observed; therefore, both two factors cannot be independently evaluated regarding POL%. In addition, it was found that the sucrose amount from the plant production in the evaluated period presented significant differences between the cutting stages only for one variety, namely CTC2, which was different from the others in most of the cutting stages. Considering the observed results, it can be concluded that analyzing sucrose amount statistically in the mill production can allow producers to posteriorly better monitor information on the sugarcane varieties harvested under mechanized processes.

Visible Losses in Mechanized Harvesting of Sugarcane Using the Case IH A4000 Harvester

Sugarcane is a major Brazilian agricultural product. The area cultivated in the state of Rio de Janeiro for the 2011-12 crop was of 41.31 thousand hectares. The process of mechanized harvesting of the crop still has many visible losses of raw materials caused by several factors. This study aimed at evaluating the visible losses of sugarcane and ratoon damage using the Case A4000 harvester and was conducted in the municipality of Campos dos Goytacazes, in the state of Rio de Janeiro, Brazil. The materials left on the field by the harvester were collected in six ratoon cane rows, with a length of 350 m, setting the frame sampling to every 50 m. The sampling area consisted of 20 m2, with eight repetitions. The losses were calculated in t&middotha-1 and in %. The comparison of averages was performed by using the confidence interval, constructed by statistical “t” at 5% probability to compare the types of losses. The estimated productivity of the area was of 54 t&middotha-1. The differences between the types of losses were significant. The billets and splinters were found in greater quantity.

Piezoionics:Mechanical-to-ionic transduction for sensing,biointerface,and energy harvesting

Piezoionic materials consisting of a polymer matrix and mobile ions can produce an electrical output upon an applied pressure inducing an ion concentration gradient.Distinct from charges generated by the piezoelectric or triboelectric effects,the use of generated mobile ions to carry a signal closely resembles many ionic biological processes.Due to this similarity to biology,the piezoionic effect has great potential to enable seamless integration with biological systems,which accelerates the advancement of medical devices and personalized medicine.In this review,a comprehensive description of the piezoionic mechanism,methods,and applications are presented,with the aim to facilitate a dialogue among relevant scientific communities.First,the piezoionic effect is briefly introduced,then the development of mechanistic understanding over time is surveyed.Next,different types of piezoionic materials are reviewed and methods to enhance the piezoionic output via materials properties,electrode interfaces,and device architectures are detailed.Finally,applications,challenges,and outlooks are provided.With its novel properties,piezoionics is expected to play a key role in the overcoming of grand challenges in the areas of sensing,biointerfaces,and energy harvesting.

Heavy soil drying during mid-to-late grain filling stage of the main crop to reduce yield loss of the ratoon crop in a mechanized rice ratooning system

Yield loss(Y_(Loss)) in the ratoon crop due to crushing damage to left stubble from mechanical harvesting of the main crop is a constraint for wide adoption of mechanized rice ratooning technology.Soil drying before the harvest of the main crop has been proposed to overcome this problem.The objective of this study was to determine the effect of soil drying during the mid-to-late grain filling stage of the main crop on grain yield of the ratoon crop in a mechanized rice ratooning system.Field experiments were conducted to compare Y_(Loss) between light(LD) and heavy(HD) soil drying treatments in Hubei province,central China in 2017 and 2018.Y_(Loss) was calculated as the percentage of yield reduction in the ratoon crop with the main crop harvested mechanically,relative to the grain yield of the ratoon crop with the main crop harvested manually.In comparison with LD,soil hardness was increased by 42.8%-84.7% in HD at the 5-20 cm soil depth at maturity of the main crop.Soil hardness at 5 and 10 cm depths reached respectively 4.05 and 7.07 kg cm^(-2) in HD.Soil drying treatment did not significantly affect the grain yield of the main crop.Under mechanical harvesting of the main crop,HD increased the grain yield of the ratoon crop by 9.4% relative to LD.Consequently,Y_(Loss) was only 3.4% in HD,in contrast to 16.3% in LD.The differences in grain yield and Y_(Loos) between the two soil drying treatments were explained mainly by panicles m^(-2),which was increased significantly by HD in the track zone of the ratoon crop compared with LD.These results suggest that heavy soil drying practice during the mid-to-late grain filling stage of the main crop is effective for reducing Y_(Loss) of the ratoon crop in a mechanized rice ratooning system.

Recent progress and future prospects for mechanized harvesting of fruit crops with shaking systems

Mechanized harvesting technologies with shaking systems for fruit industry have been widely investigated and significantly developed over the past several decades which were presented by a large amount of literature.This paper reviews the research and development progress of mechanized harvesting of fruits systematically with a focus on the theoretical study,fruit crop variety,shaking system categories,abscission chemical agents,and their actual applications.Based on the comprehensive review,mechanized harvesting systems for different fruit crops appear multifarious shaking modes with various vibratory mechanisms and structural dimensions.Major advantages in the development of fruit mechanical harvesting with effective vibratory patterns and catching frames provide a series of economic and agronomic benefits,such as reducing labor costs,promoting standardized planting,and increasing productivity.However,fruit injury and tree damage are the main reasons why mechanical shaking systems are rarely used for fresh fruit harvesting because of tenderness and frangibility of the fruit crops.Therefore,more efforts should be concentrated on the innovative shake-and-catch system with suitable frequency and amplitude to achieve low fruit damage or even nondestructive harvesting for fresh fruit market.This overview summarized the advantages and bottlenecks of these shaking systems for fruit harvesting and proposed the challenges and some constructive prospective viewpoints aimed at the major issues of mechanical harvesting techniques.In addition,employing sorting technologies to classify the postharvest fruits provide a new direction for the further development of mechanized harvesting in high-value fruit crops,as well as bring more benefits to growers and increase their interest in equipment investment on the mechanical shaking harvester for the fruit industry.

Electrospun ZnSnO_(3)/PVDF‑HFP Nanofibrous Triboelectric Films for Efficient Mechanical Energy Harvesting

Nowadays,triboelectric nanogenerators(TENGs)are one of the most emerging technologies owing to their easy and costeffective device structure.TENGs can harvest mechanical energy from our living environment.Herein,we synthesized dielectric zinc tin oxide(ZnSnO_(3))nanoparticles(NPs)by a hydrothermal technique.The ZnSnO_(3)NPs provide a dielectric and piezoelectric effect,which can efficiently enhance the output electrical performance of the proposed TENG.The prepared ZnSnO_(3)NPs were embedded into a polyvinylidene fluoride hexafluoropropylene(PVDF-HFP)polymer to prepare ZnSnO_(3)/PVDF-HFP nanofibrous films to fabricate a TENG.The output performance of TENG was investigated and optimized by varying the loading concentration of ZnSnO_(3)NPs in PVDF-HFP fibrous films.The highest voltage,current,charge density,and power density from the fabricated TENG were achieved as~138 V,~5μA,~52μC/m2,and~1.6 W/m2,respectively.Additionally,the robustness of the TENG was studied via the long-term mechanical stability test.Finally,the practical and real-time application of the TENG was demonstrated by harvesting mechanical energy to power low-power portable electronic devices.Furthermore,the materials used in the TENG were combined into a skipping rope to harvest biomechanical/mechanical energy while exercising.

Grain dehydration rate is related to post-silking thermal time and ear characters in different maize hybrids

Mechanized grain harvest of maize becomes increasingly important with growing land plot size in Northeast China. Grain moisture is an important factor affecting the performance of mechanized grain harvest. However, it remains unclear what influences grain dehydration rate. In this study, maize grain dehydrating process was investigated in a two-year field experiment with five hybrids under two planting densities in 2017 and 2018. It was found that damaged-grain ratio was the main factor affecting mechanized harvest quality, and this ratio was positively correlated with grain moisture content at harvest(R^(2)=0.6372, P<0.01). To fulfill the national standard of <5% damaged-grain ratio for mechanized grain harvest, the optimal maize grain moisture content was 22.3%. From silking to physiological maturity, grain dehydrating process was mostly dependent on the thermal time(growing degree days, GDDs)(r=-0.9412, P<0.01). The average grain moisture content at physiological maturity was 29.4%. Thereafter, the linear relationship between GDDs and grain moisture still existed, but the correlation coefficient became smaller(r=-0.8267, P<0.01). At this stage, grain dehydrating process was greatly affected by genotypes. Grain dehydrated faster when a hybrid has a smaller husk area(r=0.6591, P<0.05), larger ear angle(r=-0.7582, P<0.05), longer ear peduncle(r=-0.9356, P<0.01) and finer ear(r=0.9369, P<0.01). These parameters can be used for breeders and farmers to select hybrids suitable for mechanized grain harvest.

Relationship of Milk Line Position with Grain Weight and Mechanized Harvest of Summer Corn

To investigate the relationship of milk line position with grain weight and mechanized harvest of summer corn in Huang-Huai-Hai Region, 8 varieties （A, B, C, D, E, F, G, H） with large planting areas were selected to measure the grain filling rate, 100-grain weight, water content and milk line position, and the correlation was analyzed. Results showed that when the milk line position was 90%, the grain filling of all the 8 varieties finished and 100-grain weight reached the highest value, which was 43.02 g. The grain filling time was in positive correlation with 100-grain weight. However, when the milk line position completely disappeared, the 100-grain weight was reduced by 8.66% at most. There was no significant difference during the periods of grain weight rising, but in the periods of grain weight falling, the traits of D, E, H were significantly different with the other varieties, and water loss rate of C and A showed significant difference with the other six varieties. The water content of grain was negatively correlated with milk line position. When the milk line percentage was 90% , the grain water content was less than 30% . The key factor influencing the mechanized harvest of summer corn is harvesting time, rather than the varieties. Moreover, milk-line position of 90% is the best time for harvest; if the harvest is too late, the yield will be reduced with varying degrees.

Effects of Different Drip Irrigation Modes on Growth and Yield of Cotton

This study aimed to explore the optimum drip irrigation belt arrangement mode for mechanically-harvested cotton in Xinjiang. The Xinluzao 61 was selected as the experiment material, and the effects of two different drip irrigation modes（6 cotton rows with 2 drip irrigation pipes under plastic film, 6 cotton rows with 3 drip irrigation pipes under plastic film） on the growth and yield of Xinluzao 61 were investigated under mechanical harvest. The results showed that under the mode of 6 cotton rows with 2 drip irrigation pipes, the growth rate of edge-row cotton was lower in the early growth period, and its emergence rate and agronomic traits were all lower than those of the interior-row cotton; under the mode of 6 cotton rows and 3 drip irrigation pipes, the difference in cotton growth between edge and interior rows was smaller. The yield and benefit under the mode of 6 cotton rows with 3 drip irrigation pipes were higher than those under the mode of 6 cotton rows and 2 drip irrigation pipes by 255 kg/hm^2 and 1 500 yuan/hm^2, respectively. Therefore, the cultivation mode of 6 cotton rows with 3 drip irrigation pipes under plastic film should be promoted in the production.

Design and Guideline Rules for the Performance Improvement of Vertically Integrated Nanogenerator

Piezoelectric nanowires have attracted much scientific interest in the last few years because of their enhanced piezoelectric coefficients at nanometer scale, with promises of efficient mechanical energy harvesters for autonomous integrated systems. This paper presents the design and, for the first time, guideline rules, based on simple analytical expressions, to improve the performance of a mechanical energy harvester integrating vertical ZnO piezoelectric nanowires. Additional simulations were carried out to account more realistically for device geometry. The authors discuss the prospects of such an approach, based on design and material improvement.

Design and initial testing of a maize cob collection system

Maize cobs are valuable plant residues that can be used for many different purposes,including as a renewable energy source.Despite their value,maize cobs are still underutilized,mainly because people are not aware of their potential and harvesting techniques for their collection are still being developed.Therefore,this research focused on finding the most suitable energy-and time-efficient method for mechanical collection of maize cobs.Upgrading the combine harvester with an additional hopper proved to be the most promising solution,as it allows harvesting and storage of maize grain and maize cobs in one pass,while the harvesting time remains almost the same and the maize cobs are of good quality,as they do not fall on the field.A prototype with enlarged openings in the straw walkers,an additional grab container for maize cobs,a transport auger,a transport cleaning fan with built-in knives,a transport tube and some other assemblies was fabricated and used in practice.The first test results are very encouraging(94.4%-96.0%purity of maize cobs)and the system has been patented as a promising solution,especially in times when the environmental sustainability of the planet and energy independence are becoming increasingly important.

Flexible multilayer MEMS coils and their application in energy harvesters

Electromagnetic vibration energy harvesters are promising for the power supply of wireless sensor nodes,small electronic devices,and wearable electronics.Conventional electromagnetic harvesters usually increase output by increasing the size of coils and magnets,limiting the improvement of energy conversion efficiency and power density.In this study,multilayer microelectromechanical system(MEMS)coils were prepared using flexible electronics,and their high integration performance in arbitrary space was utilized to greatly improve the utilization of the space magnetic field by the electromagnetic harvester.The core magnet of the generator was magnetically balanced to achieve levitation,which improved the sensitivity and reduced fatigue damage compared with traditional spring structures.The wound coils on the top and bottom of the magnet and the flexible coils on the sides worked together to improve the energy efficiency and output of the devices.The output performance of the device with different number distributions was simulated using mathematical models to obtain the optimal structural parameters.The results show that by introducing flexible multilayer MEMS coils on the side surface of the energy harvester,the open-circuit voltage of the energy generators increased from 7 to 10 V by more than 43%.Flexible multilayer MEMS coils can enhance energy conversion rates and possess compact dimensions,making them suitable for integration onto complex surfaces.After the vibration energy harvesting system testing,the maximum peak power of the harvester was 7.1 m W at an acceleration of1 g and a resonant frequency of 11 Hz with a resistor of 3.5 kΩinternal resistance.Moreover,a 470μF capacitor can be charged to 3.5 V within 10 s to drive a hygrothermograph to work for more than 80 s and can supply a light bulb continuously.This strategy shows the great potential of vibration-energy-driven electromagnetic generators for powering small electronics in limited spaces.

Dynamic characteristics of dwarf Chinese hickory trees under impact excitations for mechanical fruit harvesting

Mechanical vibration is an effective fruit harvesting method.To evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact excitation.The primary resonance frequencies of the tree can be determined based on the acceleration admittance measurement.The effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was tested.The responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree specimen.The results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree structure.The attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter is.Unlike the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain configuration.The branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration transmission.For those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance frequencies.To impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.

Design and evaluation of a two-section canopy shaker with variable frequency for mechanical harvesting of citrus

Canopy shaking is one of the most commonly used techniques for mechanical harvesting of citrus fruits in orange juice industry.However,tree damage and low harvesting efficiency are the top concerns of growers in adopting the existing harvesting equipment on a large scale.The purpose of this research was to develop a novel canopy shaking system to minimize tree damage and maximize fruit removal for mechanical citrus harvesting.In this study,a two-section canopy shaker composing of top and bottom shaking systems mounted on two rotating drums was proposed and developed.It was configured with two sets of flexible bow-shaped shaking rods in a staggered distribution,which can shake the top and bottom zones of the tree canopy independently.The shaking system was designed based on a linked crank-rocker mechanism.Kinematic simulation analysis was conducted to verify the quick return characteristics and differential properties of this mechanism.Vibration test showed that the frequency of the shaking rod could be adjusted within a range of 1.1-8.8 Hz related to hydraulic motor speeds.The field tests of the shaking system with an average frequency of 4.7 Hz achieved a fruit removal percentage of 82.6%and tree damage rate of 5.4%under a tractor speed of 3 km/h.By contrast,the combined shaking frequency of 4.7 Hz&4.1 Hz of the canopy shaker produced less tree damage with a percentage of 3.9%.This study indicated that the two-section canopy shaker with an optimized frequency combination could be adaptable to the different zones of the tree canopy,and obtain lower tree damage and higher fruit removal percentage.

Allocation of maize varieties according to temperature for use in mechanical kernel harvesting in Ningxia, China

The reasonable assessment of maize varieties in different ecological regions can allow temperature resources to be fully exploited and reach the goal of high yield and efficiency and is thus an important direction of modern maize development in China.In this study,a logistic power nonlinear growth model was used to simulate the accumulated temperature required for kernel dehydration to moisture contents of 25%,20%,and 16%for various maize cultivar,which were divided into six types based on the accumulated temperature required for kernel dehydration to a moisture content of 25%.The relationship between the yield of maize cultivars and the accumulated temperature required for kernel dehydration to a moisture content of 25%was found to follow a unary function model.Changing the planted maize variety was found to increase economic returns by more than 7000 RMB/hm2 in Ningxia,Northwest China.Under the conditions of mechanical grain harvesting,economic benefits can be further increased by means of selecting high yields and fast-dehydrating varieties,selling when the grain dehydration is below 16%.A better way to achieve grain dehydration to a moisture content below 16%is to postpone the harvest date as much as possible rather than drying after the harvest at physiological maturity.The areas of various types of maize varieties can be dehydrated to moisture contents of 25%,20%,and 16%were marked.Based on the distribution of heat resources in different regions of Ningxia from the normal sowing date to October 31 before winter irrigation,the appropriate cultivars for various regions in the province were determined based on production benefits.Therefore,in different areas of Ningxia,selecting suitable maize varieties according to temperature resources can reach a high yield and mechanical kernel harvesting,and ultimately obtain higher economic benefits.