Design and experimental research on the sweet potato seedling transplanting mechanism of the planetary gear train with deformed elliptical gear transmission

Aiming at the lack of suitable machines for sweet potato seedling transplanting in China,and according to the agronomic requirements for the horizontal insertion method of sweet potato seedling,a new sweet potato seedling transplanting mechanism of planetary gear train was proposed based on the non-uniform transmission of deformed elliptical gear.The working principle of the transplanting mechanism was analyzed,and the kinematics modeling and analysis of the mechanism were carried out.The study established the numerical objectives of the transplanting mechanism and applied the theory of membership function to establish a mathematical model for the parameter-guided optimization design of the transplanting mechanism.The parameter-guided optimization design software was developed to obtain a set of optimal mechanism parameters that satisfied the motion trajectory of sweet potato transplanting and the posture of the transplanting arm.Based on the optimized parameters,the structure of the transplanting mechanism was designed,and a virtual prototype of the mechanism was created,whereby a virtual motion simulation of the transplanting mechanism was conducted to verify the correctness of the kinematics model and design of the mechanism.The high-speed photographic kinematics test of the mechanism prototype and sweet potato seedling transplanting tests were conducted to test the mechanism’s kinematic characteristics and transplanting performance.The test results show that the test trajectory of the mechanism and test posture of the transplanting arm are almost consistent with the theoretical and simulation trajectory,meeting the agronomic requirements of the horizontal insertion method of sweet potato seedling;And when the rotary speed of the mechanism are 20 r/min and 30 r/min,the average success ratios of sweet potato seedlings transplanting are 90%and 82%,respectively,which prove the application feasibility of the mechanism in the practical machines.

Optimization design and test of rice plug seedling transplanting mechanism of planetary gear train with incomplete eccentric circular gear and non-circular gears

In order to solve the problem of the high-speed mechanized transplanting of rice plug seedlings,the design requirements of transplanting mechanism for rice plug seedlings were analyzed and a kind of rice plug seedling transplanting mechanism of planetary gear train based on the drive with incomplete eccentric circular gear and non-circular gears was designed innovatively.The laboratory kinematics was examined.The working principle of the transplanting mechanism for rice plug seedlings was studied,kinematics analysis of the transplanting mechanism was carried out and its kinematic model was set up.A human-computer interaction optimization method was used to optimize the parameters of the transplanting mechanism.The computer aided analysis and optimization software of the transplanting mechanism based on Visual Basic 6.0 was developed.Through analyzing the influence of design variables on the optimization objectives of the transplanting mechanism,a set of parameters of the transplanting mechanism which meet the requirements of transplanting trajectory and posture for transplanting rice seedlings were obtained by means of human-computer interaction.The structure of the transplanting mechanism was designed according to this set of parameters,and its virtual prototype and physical prototype were set up and manufactured,respectively.The kinematic simulation test and high-speed photography kinematic test of the transplanting mechanism were conducted to obtain its kinematic performances,such as transplanting trajectory and posture.The results of bench test,simulation analysis and theoretical analysis were almost in agreement,which verified the correctness of the theoretical model and design results of the transplanting mechanism,indicating that the optimized transplanting mechanism can satisfy the requirements of transplanting rice seedlings and be applied in the rice plug seedling transplanter.

Optimized design and experiment of the three-arm transplanting mechanism for rice potted seedlings

The transplanting arm of two-arm transplanting mechanism is easy to cause seedlings injury and missing due to its faster speed relative to the seedlings.In order to solve the existed problems,a three-arm transplanting mechanism for rice potted seedlings was developed in this study.The developed three-arm transplanting mechanism for rice potted seedling can make the transplanting arm realize special trajectory and attitude through the unequal planetary gear transmission.The kinematic model of three-arm transplanting mechanism for rice potted seedling was established,and the optimal design software was developed.Based on the heuristic optimization algorithm named“parameter guide”,a set of satisfied mechanism parameters required by the rice potted seedling transplanting were obtained.The trajectory and attitude of three-arm transplanting mechanism used for the rice potted seedling were analyzed.Besides,the virtual simulation results were basically consistent with the optimization software results,and the correctness of theoretical analysis and virtual simulation were also verified by each other.When the developed transplanting mechanism picked up the seedling,the velocity of transplanting arm relative to the seedling was reduced by about 30%.The results showed that the injury rate of rice potted seedling transplanting mechanism was 0.04%,the missing rate of seedling was 1.4%,the integrity rate of seedling pot matrix was 96%,and the success rate of picking seedling was 99.92%.

Optimized design and experiments of a rotary-extensive-type flowerpot seedling transplanting mechanism

To realize the mechanization of flowerpot seedling transplanting,a creative mechanism to transplant flowerpot seedlings was designed.The mechanism is based on noncircular gear in combination with a transplanting arm equipped with an extensive seedling pick-up device to transplant the flowerpot seedlings from the growing tray to the flowerpot,which in accordance with the transplanting agronomy requirements.The working principles of a theoretical model and kinematic characteristics of the transplanting mechanism were analyzed.The computer-aided analysis and optimization software based on Visual Basic 6.0 was developed and used to obtain a set of special trajectory and attitude parameters satisfying the transplanting operation requirements.The optimized parameters were used for virtual manufacturing and simulation testing of the transplanting mechanism.The virtual prototype testing results are consistent with the theoretical analysis,verifying the structural design validity and rationality.The high-speed photography was used in a bench test of the transplanting mechanism with“Salvia Splendens”pot seedlings as test samples.The trajectory and attitudes of the theoretical analysis,virtual test,and physical prototype test were essentially identical.The bench test results showed that the success rate was 91.67%for the seedling pick-up device penetrating into the root mass at 35 mm,thus,the quality of the extracting seedling was satisfactory.

Method for generating non-circular gear with addendum modification and its application in transplanting mechanism

With a focus on the design of tooth profiles of non-circular gears with addendum modifications that conform to the given complex transmission ratio curves and based on a series of discrete point sets on the pitch curves,the criteria for tooth profile distortion and undercut in non-circular gears were proposed.With the constraint of no tooth profile distortion and undercut,the addendum modification coefficient was introduced into the calculation of the distorted and undercut segments of the tooth profile of a non-circular gear,and the addendum modification coefficient of each contact point of the non-circular gear was obtained.Based on the generating principle for gear shaping with gear cutters,a theoretical model for calculating the tooth profile of non-circular gears with addendum modification was derived.The cutting and radial feeding motions of the pinion cutter were ignored,and only the meshing motion was considered.The involute tooth profiles of the pinion cutter enveloped the tooth profile of the non-circular gear.3D automatic non-circular gear model generation software was developed,which was a secondary development product of the software UG.A non-circular gear in a rice potted seedling transplanting mechanism was designed,and the transplanter was developed and tested.The test results showed that the designed tooth profile of non-circular gear achieved the variable transmission ratios required by the transplanting mechanism.When the transplanting efficiencies were 140 plants/min,160 plants/min and 180 plants/min,the transplanter completed the rice potted seedling transplanting operation with high quality.

Effects of Mechanized Transplanting and Fertilization Mode on Population Growth and Development of Male Parent in Seed Production of Hybrid Rice

In order to study the effects of mechanized transplanting and fertilization mode on population growth and development of the male parent in seed production of hybrid rice, three male parents, Huazhan, Shuhui 527 and R9311 were selected as materials. The male parents were transplanted by rice transplanter with two kinds of line spacing design, six lines with equal row spacing （20/25 cm x 30 cm） and wide and narrow spacing （20/25 cm x 40, 20 cm）, and artificial transplanting with equal row spacing （20/25 cm x 30 cm） was set as the control. The three fer- tilization modes were applying for one, two and three times. The flowering stage and panicle-spikelet structure of the male parent were investigated. The results showed that the effects of mechanized transplanting and fertilization mode were little on the duration from seeding to heading; the panicles and spikelets of the three male parents were significantly increased by mechanized transplanting. The tiller number was increased by mechanized transplanting and fertilizing for two and three times. Wide and narrow spacing by machine planting and fertilizing for three times were suitable for Huazhan, which significantly increased the number of spikelets per unit area. Furthermore, the number of spikelets per unit area of Shuhui 527 and R9311 were significantly increased by mechanized transplanting and fertilizing for three times.

Effects of Farming and Seedling-raising Methods on Population Growth and Grain Yield of Mechanized Transplanting Rice

The effects of farming method, rice variety and seedling-raising method were studied on the population growth quality and grain yield of the mechanized transplanting rice by way of three-factor split plot design. The results showed that the no-tillage mechanical transplanting treatment was poorer than the conventional mechanical transplanting treatment in transplanting quality in general, but the former was similar to the latter in population growth quality. In regard to grain yield, the no-tillage mechanical transplanting treatment was lower than the conventional me- chanical transplanting treatment. Raising both pot-mat seedling and plastic-tray seedling did not make much difference in population growth and grain yield of mechanized transplanting rice, so both of the seedling-raising methods can be adopted according to practical conditions.

Tillering Characteristics of Different Varieties of Double-season Rice under Different Mechanical Transplanting Modes

A total of 8 early-season and late-season rice varieties with different growth periods were selected, and their tillering characteristics under wide-narrow row and equal row .transplanting modes were studied. The results showed that the length of slow growth phase was related to the performance of transplanter; the ef- fect of mechanical transplanting on tillering of early-season rice was greater than that of late-season rice; Compared with late-season rice, early-season rice showed later tillering and longer tillering period; the tiller number per plant and effective panicle number per plant differed greatly among different varieties of double-season rice; under the condition of same transplanting density, the tillers of rice under wide- narrow row transplanting mode appeared rapidly and disappeared slowly, and wide- narrow row transplanting mode improved tillering, effective panicle number and yield of rice; different varieties of double-season rice showed different adaptability to me- chanical transplanting, and the varieties with short growth period, strong tilledng a- bility and more effective panicles per plant were more suitable for mechanical trans- planting; the effect of mechanical transplanting on rejuvenation of rice could be im- proved by improving the performance of transplanter.

Major Physiological Characters of Different Double Cropping Rice Varieties by Different Mechanical Transplanting Methods

The research selected 16 rice varieties（8 early and 8 late double-cropping rice） by mechanical transplanting modes as per equivalent row and wide-narrow row to explore yield and physiological traits in order to provide references for selection of rice variety suitable for mechanical transplanting. The results showed that yields of early and late rice improved by 2.90% and 2.73% by mechanical transplanting as per equivalent row and wide-narrow row respectively. Besides, leaf area index in the treatment as per wide-narrow row was higher compared with the treatment as per equivalent row, as well as average photosynthetic potential which grew by 0.92%,3.99% and 5.64% of early from tillering-peak stage to mature stage and 3.46%,7.09% and 6.79% of late rice. Furthermore, by mechanical transplanting as per wide-narrow row, SPAD value, and root activity performer higher, as well as the number of differentiated branch and glumous flowers, but degradation rate showed lower. In addition, with mechanical transplanting the same, early rice Zhuliangyou819 and late rice Fengyuanyou 299 took advantages in yield, which can be priorities for mechanical transplanting in double-cropping areas in Jiangxi Province.

Reducing environmental risk of nitrogen by popularizing mechanically dense transplanting for rice production in China

The high nitrogen(N)application rates typically used in Chinese cropping systems have led to diminishing returns for yields and have also imposed substantial environmental costs.Here,we estimate that the annual N loss from rice production in China reached approximately 2.6×109 kg from 2011 to 2015,and we demonstrate that adoption of the mechanically dense transplanting technique by producers is an effective method to reduce N loss from rice cropping systems without suffering a yield penalty.

Nitrogen Deep Placement Combined with Straw Mulch Cultivation Enhances Physiological Traits,Grain Yield and Nitrogen Use Efficiency in Mechanical Pot-Seedling Transplanting Rice

To assess the effects of straw return coupled with deep nitrogen(N)fertilization on grain yield and N use efficiency(NUE)in mechanical pot-seedling transplanting(MPST)rice,the seedlings of two rice cultivars,i.e.,Yuxiangyouzhan and Wufengyou 615 transplanted by MPST were applied with N fertilizer at 150 kg/hm2 and straw return at 6 t/hm2 in early seasons of 2019 and 2020.The experiment comprised of following treatments:CK(no fertilizer and no straw return),MDS(deep N fertilization and straw return),MBS(broadcasting fertilizer and straw return),MD(deep N fertilization without straw return),MB(broadcasting fertilizer without straw return).Results depicted that the MDS treatment significantly increased the rice yield by 41.69%-72.22%due to total above-ground biomass,leaf area index and photosynthesis increased by 54.70%-55.80%,38.52%-52.17%and 17.89%-28.40%,respectively,compared to the MB treatment.In addition,the MDS treatment enhanced the total N accumulation by 37.74%-43.69%,N recovery efficiency by 141.45%-164.65%,N agronomic efficiency by 121.76%-134.19%,nitrate reductase by 46.46%-60.86%and glutamine synthetase by 23.56%-31.02%,compared to the MB treatment.The average grain yield and NUE in both years for Yuxiangyouzhan were higher in the MDS treatment than in the MD treatment.Hence,deep N fertilization combined with straw return can be an innovative technique with improved grain yield and NUE in MPST in South China.

Comparison of agronomic performance between inter-sub-specific hybrid and inbred japonica rice under different mechanical transplanting methods

Mechanical transplanting has been applied to rice cultivation to save labor costs and ease labor shortages in Asian countries, especially in China. However, little information is available related to the characteristics of agronomic performance when comparing inter-sub-specific hybrid rice(IHR) and inbred japonica rice(IJR) under mechanical transplanting method. In 2013 and 2014, field experiments were conducted using IHR(Yongyou 2640) and IJR(Wuyunjing 24) under two cultivation patterns, that is, pot seedlings mechanically transplanted(PS) and carpet seedlings mechanically transplanted(CS). Grain yield, yield components, leaf area index(LAI), leaf area duration(LAD), aboveground biomass, crop growth rate(CGR), nitrogen(N) uptake, and N accumulation were investigated. When compared with CS, PS displayed significantly increased grain yield for both varieties because the larger sink size allowed higher N accumulation from panicle initiation to maturity. Moreover, total aboveground biomass under PS increased significantly compared with that under CS; that is, higher photosynthetic productivity resulted from a greater LAI and higher LAD during the grain filling stage. Higher N absorption capacity in the middle and late growth periods resulted in significantly enhanced total N uptake under PS. When compared with IJR for both treatments, IHR generated 75.2% more grain yield. However, the characteristics creating high yield of IHR were different from those of IJR. Greater aboveground biomass production as well as higher N uptake and accumulation created higher grain yield in IHR than in IJR. These results suggest higher yield could be achieved using PS with IHR, attributing to exploit both yield superiority and productive potential.

Critical Yield Factors for Achieving High Grain Yield in Early-Season Rice Grown under Mechanical Transplanting Conditions

Double-season rice cropping systems occupy a large portion of the rice production area in southern China.Because the problem of insufficient labor,mechanical transplanting(in contrast to the manual transplanting)was become more attractive in double-season rice system.However,the decisive yield factors which resulting in high grain yield of early-season rice are unclear under mechanical-transplanted conditions.In present study,the field experiments were conducted in the early season in 2017 and repeated in 2018 in Santang Town,Hunan Province,China.Ten early season rice cultivars(Zhuliangyou 819,Lingliangyou 268,Lingliangyou 104,Luliangyou 996,Xiangzaoxian 24,Xiangzaoxian 32,Xiangzaoxian 45,Xiangzaoxian 42,Zhongjiazao 17,and Zhongzao 39)were used as materials in this study.The difference in grain yield and closely-related agronomic and physiological traits of ten tested cultivars were compared.The range of yields(t ha^(–1) at 86%dry matter)in 2017 was 6.2 to 8.7(mean 7.8)and in 2018 was 6.5 to 8.4(mean 7.8).Grain weight and pre-heading biomass accumulation had potent significant positive correlations with the grain yield.The greater pre-heading biomass accumulation was major attributed to higher apparent radiation use efficiency.Our results suggested that early-season rice cultivars to achieve the high grain yield in mechanical-transplanted conditions depends on apparent radiation use efficiency in the pre-heading period and higher grain weight.

Role of OX40 in mechanisms of memory T cells in islet transplant tolerance

Objective To investigate the role of OX40 in the mechanisms of memory T cells in islet transplant tolerance. Methods The expression of OX40 on native, like memory and memory CD8 + T cells was detected by RT - PCR. Splenic T ceels from B6 mice were injected into Rag - / - mice via the tail vein,and the Rag mice were divided into three groups ( n = 8 each) :

Effects of Seed Rate on Root Twining Power and Seedling Quality of Machine-transplanted Super Rice

In order to investigate the effects of seed rate on root twining power and seedling quality of machine-transplanted super rice cultivars, Yongyou 12 and Zhongzheyou No.l, total 6 seed rates were arranged, and the growth characteris- tics, quality and root twining power of machine-transplanted rice seedlings were studied. The results showed that seed rate had great effects on root twining power and qualityof rice seedlings; with the increase of seed rate, the root twining power of rice seedlings was increased, but the quality of rice seedlings was significantly reduced; under the condition of high seed rate, rice seedlings were weak with less accumulate dry matter and nonuniform growth, and the proportion of weak seedlings was higher. When the seed rate of both rice cultivars was reduced by 10 g/tray, the average seedling height was increased by 0.5 cm, leaf age was increased by 0.1, stem base diameter was increased by 0.1 cm, and root number per plant was increased by 0.3. When the seed rate was increased by 10 g/tray, the accumulated dry matter per plant was reduced by 5.1 mg. With the increase of seed rate, the seedling quality of Zhongzheyou No.1 was decreased rapidly, and the proportion of weak seedlings was increased rapidly. However, Yongyou 12 has a larger elasticity in seed rate. When the seed rate reached to 50 g/tray, blanket seedlings of Yongy- ou 12 were nursed with uniform growth and higher quality, but the shoots were sparse with lower leaf area index. However, when the seed rate was up to 50 g/tray, blanket seedlings of Zhongzheyou No.1 were nursed with uniform growth and higher quality, as well as higher-density shoots. From a comprehensive point of view, the optimum seed rates of Yongyou 12 and Zhongzheyou No.1 were 65 and 50 g/tray, respectively.

Theoretical analysis and development of a mechanism with punching device for transplanting potted vegetable seedlings

Several studies have indicated that potted vegetable seedling transplanting technology can greatly improve the ability of vegetable seedlings to resist cold,flood,drought,saline-alkali and pests.The existing transplanting equipment mostly adopts mechanical,electrical and hydraulic integration technologies with a complex structure and a high cost.To address the problems of the complex structure and low efficiency of existing transplanting equipment,a rotary transplanting mechanism for potted vegetable seedlings was developed through configuration analysis and optimization design.Through kinematic analysis of the transplanting mechanism,optimization design software was developed,and the parameters were optimized.A mechanism was developed for picking,transporting,hole punching and transplanting potted vegetable seedlings.The virtual simulation results showed that the maximum error of attitudes of the transplanting arm is less than 1.19°and that of the hole punching shovel is less than 1.7°.In this study,perforation,seedling harvesting and transplanting experiments were conducted through a bench test.The results showed that the specific trajectory and attitude of the potted vegetable seedlings transplanting mechanism conformed to the requirements of potted vegetable seedling transplantation and the success rate of seedling picking was 92.4%,which verified the correctness and feasibility of the rotary potted vegetable seedling transplanting mechanism.

Effects of Different Application Times of Tillering Fertilizer on Grain Yield and Population Development of Double-cropping Rice Transplanted by Machine

The application of tillering fertilizer plays an important role in promoting rice tillering and improving rice yield. However, under the condition of mechanical transplanting, the optimal application time of tillering fertilizer is still unclear. In this study, the early rice cultivar Zhongjiazao 17 and late rice cultivar H You 518 were used as materials, and the effects of different application times of tillering fertilizer on yield and population development of double-cropping rice transplanted by machine were investigated. The tillering fertilizer was applied 7（D07）, 10（D10） and 13（D13） d after the transplanting, respectively. The results showed that compared with those in the D07 treatment groups, the yield of early rice in the D10 and D13 treatment groups were reduced by 9.4% and 3.8%, respectively, and the yield of late rice in the D10 and D13 treatment groups were reduced by 4.5% and 12.6%,respectively. However, there were no significant differences in rice yield among the treatment groups. The application time of tillering fertilizer showed significant effects on grain number per panicle and seed setting rate of early rice. The grain number per panicle in the D10 treatment group was significantly lower than that in the D07 treatment group, and the seed setting rate of the D13 treatment group was significantly lower than that in the D07 treatment group（P〈0.05）. For the late rice, the effect of application time of tillering fertilizer on effective tiller number was most obvious, and the effective tiller number in the D13 treatment group was significantly lower than that in the D07 treatment group（P〈0.05）. Compared with those in the D07 treatment group, the effective tiller numbers, leaf area indexes and biomasses in the D10 and D13 treatment groups were all trended to be decreased. Therefore,to improve the quality of population and fulfill the high-yielding potential of double-cropping rice transplanted by machine, the tillering fertilizer should be applied as early as possible after rice seedlings turn green.

Effect of Seedling Raising Methods on Leaf Photosynthesis and Grain Yield of Mechanically-transplanted Japonica Rice

This study was conducted to investigate the effects of seedling raising modes on photosynthetic charactedsticsand grain yield under wheat straw returning. Four representative cultivars in Huaibei area were selected as test materials. By setting potted seedlings and carpet seedlings, the effects of different nursery meth- ods on the photosynthesis of rice at different growth stages in Huaibei area were investigated. Compared with carpet seedlings, the leaf area index of potted seedlings decreased at the maturation stage, but the dry weight of leaf shewed no significant difference.The SPAD of potted seedlings had an increasing trend after transplanting, but the SPAD increased differently according to cultivars. The net photosynthetic rate, stomatal conductance and transpiration rate of the leaves of pot seeding rice were significantly higher than those of carpet seedling rice on the 85^th d after transplanting. However, theintracellular CO2 concentration and water use efficiency of leaves had no significant differences between different ＇treatments. The results indicate that the photosynthetic capacity of flag leaves of pot seedling rice is stronger in early and middle stages, but the decay rate of photosynthetic function is slightly faster than carpet seedling rice, which might be the main reason for the rice yield of potted seedlings having no remarkable difference from carpet seedlings.

Yield potential and stability in super hybrid rice and its production strategies

China＇s Super Hybrid Rice Breeding Program has made significant progress over the past two decades. In this paper, we reviewed our studies on the yield potential and stability in super hybrid rice and discussed the strategies for super hybrid rice production. The results of our studies show that rice yield potential has been increased by 12% in super hybrid cultivars as compared with ordinary hybrid and inbred cultivars. The higher grain yields in super hybrid rice cultivars are attributed to larger panicle size coupled with higher biomass production or higher harvest index. However, grain yields in super hybrid rice cultivars vary widely among locations depending on soil and climatic factors. Therefore, it is important to tailor target yield to local conditions in super hybrid rice production. The target yield for super hybrid rice production can be determined by the average yield method or the regression model method. Improving soil quality is critical to achieving the target yield in super hybrid rice production. Favorable crop rotations such as rice-oilseed rape and novel soil management practices, such as biochar addition, are effective approaches to improve soil quality. It is needed to develop simplified cultivation tech- nologies for super hybrid rice to meet the changes in socioeconomic environments during the period of transition. There are such technologies as no-tillage direct seeding and mechanized transplanting at high hill density with single seedling per hill.

Comparison of yield traits in rice among three mechanized planting methods in a rice-wheat rotation system

Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting （PSMT）, carpet seedling of mechanical transplanting （CSMT） and mechanical direct seeding （MDS） is of great importance not only for rice scientists but also for rice farmers to develop a high-yield production system under mechanical conditions in a rice-wheat rotation system. However, such traits are yet to be studied among rice varieties ofjaponica-indica hybrid rice （JIHR）,japonica conventional rice （JCR） and indica hybrid rice （IHR）. Field experiments were conducted in 2014 and 2015, where six cultivars of the three rice types JIHR, JCR and IHR were grown individually with PSMT, CSMT and MDS methods, under respective managements for each method to achieve the maximum attainable yield. Results showed that （i） the PSMT significantly increased grain yield of JIHR by 22.0 and 7.1%, of JCR by 15.6 and 3.7% and of I HR by 22.5 and 7.4%, compared to MDS and CSMT on average across the two years, respectively. The highest yield was produced by the combination of JIHR and PSMT; （ii） high yield under PSMT was mainly attributed to large sink capacity and high-efficient dry matter accumulation. With sufficient panicles per hectare, the increase of spikelet number per panicle, especially the increase in spikelet number of the secondary rachis-branches was determined to be the optimal approach for developing a large sink capacity for rice under PSMT. The optimal tillers development, large leaf area index at heading stage, and high leaf area duration, crop growth rate and net assimilation rate during grain-filling phase could be the cause of sufficient dry matter accumulation for rice under PSMT; （iii） moreover, the PSMT favored plant growth as well as enriched the stems plus sheaths during grain-filling phase, as compared with CSMT and MDS. These results suggest that PSMT may be an alternative approach to increasing grain yield in a rice-wheat rotation system in the lower reaches of the Yangtze River in China.