Effect of Different Nitrogen Application Amount on the Net Increment of Fresh Dry Weight in Hybrid Rape

[ Objective] The aim of the research was to provide reference for reasonable application of nitrogen fertilizer for high yield.cultivation of hybrid rape cuhivar Youyan 9 and Youyan 10. [ Method] The net increment changes of individual plant fresh weight and dry matter weight of Youyan 9 and Youyan 10 with different nitrogen application treatments were studied. [ Result] The differences among average fresh weight increments of individual plant and average dry matter weight increment of individual plant with different treatments reached 0. 01 extremely significant level. Fresh weight increment and dry matter weight net increment of individual plant declined gradually with the increase of nitrogen application. In growtheourse ,fresh weight net increment of individual plant increased firstly then decreased and the maximum was in beginning flowering stage, besides that dry matter net increment increased gradually and the maximum was in mature period. The correlations among fresh net increment, dry matter weight net increment and yield net increment were positive or extremely positive. [ Conclusion] Under experimental condition, when nitrogen application was 225 kg/hm^2, hybrid rape Yanyou 9 and Yanyou 10 with low erucic,low glucosinolate could obtain high yield.

Effects of Nitrogen Level and High Temperature Stress on Yield, SPAD Value and Soluble Sugar Content of Early Rice Ganxin 203

This study aimed to investigate the combined effects of nitrogen level （high and ordinary） and high temperature stress （37 ℃, 4 d） at the late panicle ini- tiation stage on yield, SPAD value and soluble sugar content of Ganxin 203, an early rice cultivar. The results showed that under both high and ordinary nitrogen levels, high temperature stress reduced the seed-setting rate, yield per stem, SPAD value and soluble sugar content of Ganxin 203; under both high and ordinary tem- peratures, high nitrogen level increased the seed-setting rate, yield per stem and soluble sugar content of Ganxin 203; the seed-setting rate, yield per stem and yield per plant of Ganxin 203 under high temperature and high nitrogen level were higher than those under high temperature and ordinary nitrogen level. It suggests that ap- propriate high nitrogen level contributes to weakening the negative effects of high temperature stress on rice yield.

Effects of Nitrogen Fertilization on the Growth and N Uptake of Late-sowing Winter Oilseed Rape (Brassica napus L.)

[Objective] The aim of this work was to analyze the N fertilization on the vegetative growth and N uptake of different winter rapeseed varieties at wintering stage. [Method] In two consecutive years （2009-2011）, two winter rapeseed varieties （B. napus L.）, an early maturity variety Zhongyou 116 （ZY116） and a middle-late application maturity variety Zhongyouza 12 （ZYZ12） were employed. Field experiments with different N levels （0, 90, 180, 270, 360 kg N/hm 2 ） were designed. At the wintering stage, the dry matter weight, the nitrogen content and concentration of plants, leaf nitrate reductase activity （NRA） and seed yields were investigated. [Result] The shoot dry matter of ZY116 increased rapidly when N rate ranged from 0 to 180 kg/hm 2 , and it raised slightly when N rate ranged from 180 to 360 kg/hm 2 . The shoot dry matter of ZYZ12 were changed in a single peak curve; the peak of shoot dry matter appeared at 270 kg N/hm 2 . The N concentration and N content in shoot and root increased rapidly when the N rate changed from 90 to 180 kg/hm 2 . Moreover, the N concentration and N content root of in ZYZ12 were much higher than that of ZY116. Present study revealed that the changed trend of leaf nitrate reductase activities （NRA） were significantly increased at the N rate of 180 kg/hm 2 in ZY116 and ZYZ12 compared with the N rate of 90 kg/hm 2 in two years. [Conclusion] Optimal nitrogen application significantly increased the dry weights and N uptake at wintering stage as well as increasing the yield of winter oilseed rape.

Effects of Nitrogen Application Rate, Density and Seedling Age on Dry Matter Accumulation of No-tillage Rape in Seedling Stage

[Objective] The aim of the research was to find the optimal nitrogen application rate, density and seedling age for no-tillage rape in seedling stage. [Method] With the D-optimal quadratic regression design for three factors, the 310 scheme was designed to study the effects of nitrogen application rate, density and seedling age on dry matter accumulation of no-tillage rape in seedling stage. [Result] With the increase of nitrogen application rate, density and seedling age, the dry matter content appeared like a parabola, increasing firstly and then declining. The change of nitrogen application rate caused greater influence than that of density and seedling age; the interaction effects between nitrogen application rate and density were greater than that between nitrogen application rate and seedling age as well as between density and seedling age. [Conclusion] Considered comprehensively, the dry matter content of no-tillage rape in seedling stage reached the highest level (4 768.2 kg/hm2) when the nitrogen application rate, the density and the seedling age were 195 kg/hm2, 93 000 plants/hm2 and 33 d, respectively.

Responses of chlorophyll fluorescence and nitrogen level of Leymus chinensis seedling to changes of soil moisture and temperature

Controlled experiment of Leymus chinensis seedlings grown in the environmental growth chambers at 3 soil moisture levels and 3 temperature levels was conducted in order to improve the understanding how leaf photosynthetic parameters will respond to climatic change. The results indicated that soil drought and high temperature decreased the photochemical efficiency of photosystem(F v/F m), the overall photochemical quantum yield of PSII(yield), the coefficient of photochemical fluorescence quenching(q\-P), but increased the coefficient of non-photochemical fluorescence quenching(q\-N). Severe soil drought would decrease F v/F m and yield by 3.12% and 37.04% under 26℃ condition, respectively, and 6.60% and 73.33% under 32℃ condition, respectively, suggesting that higher temperature may enhance the negative effects of soil drought. All the soil drought treatments resulted in the decline in leaf nitrogen content. There was no significant effect of temperature on leaf nitrogen level, but higher temperature significantly reduced the root nitrogen content and the ratio of root nitrogen to leaf nitrogen, indicating the different strategies of adaptation to soil drought and temperature. It was also implied that higher temperature would enhance the effect of soil drought on leaf photosynthetic capacity, decrease the adaptability of Leymus chinensis to drought.

Liquid nitrogen level meter for high-temperature superconductor (HTS)

Many kinds of high temperature superconductor （HTS） power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and controlled to ensure the thermal stability and the dielectric strength as well. To measure the level, capacitance method and differential pressure method are usually used. However, each method has installation difficulties and measurement errors for unsteady state operation with varying system pressure. A new liquid level meter using a 2G HTS conductor is described, which has similar structure with the liquid helium level meter with NbTi filament. The level meter is fabricated with a parallel connected heater, which helps the separation of the superconducting region and normal region, considering the critical temperature, large heat capacity of conductor and cooling characteristics. The level of liquid nitrogen can be obtained from the measured voltage signal along the 2G HTS conductor. Design, fabrication and test results of the new liquid nitrogen level meter are presented.

Evaluating the Impact of Different Tillage Regimes and Nitrogen Levels on Yield and Yield Components of Maize (Zea mays L.)

A field study to evaluate the impact of different tillage regimes and nitrogen levels on yield and yield components of maize (Zea mays L.), was conducted during autumn 2014 at Students Farm, Department of Agronomy, University of Agriculture, Faisalabad. The experiment was laid out in RCBD (Randomized Complete Block Design), with split plot arrangement having three replications. The experiment was comprised of three tillage regimes (Minimum, Conventional and Deep) and three nitrogen levels viz: 100, 200 and 300 kg•ha-1. Urea was used as a source of nitrogen, sulphate of potash as a source of potassium and triple super phosphate as a source of phosphorous. The amount of phosphorous and potash was constant in all the treatments i.e. 125 kg•ha-1 and 100 kg•ha-1 respectively. Results of present study are summarized as yield parameters are significantly affected by different nitrogen levels and tillage regimes. Maximum number of plants at harvest (7.93), number of grain rows per cob (17.70), number of grains per row (34.31), number of grains per cob (678.58), and cob weight (187.50 g) were observed in deep tillage at 200 kg•ha-1 nitrogen application. 1000-grain weight (275.52 g), biological yield (15.66 t•ha-1), grain yield (6.16 t•ha-1) and dried stalk yield (9.91 t•ha-1) were observed maximum in deep tillage at 200 kg•ha-1 nitrogen application. Harvest index significantly affected by tillage regimes and maximum harvest index (39.58%) were recorded in deep tillage which was statistically at par with conventional tillage (38.83%). It was concluded that higher grain yield of maize can be obtained by deep tillage with the application of 200 kg•ha-1 nitrogen application under the prevailing conditions of Faisalabad.

SPAD chorophyll meter was suitable in nitrogen quick diagnosis,yield forecast and fertilization recommendation in rapeseed(Brassica napus L. )

Nitrogen （N） is one of the most important nutrients for oilseed rape （Brassica napus L . ） , but there is a lack of quick diagnosis and recommended fertilization. Three field experiments were con-ducted to seek the best diagnostic method and establish a fertilizer rate recommendation model. For ex-periment 1, six treatments as application N 0,90,180,240,300 and 400kg ha -1 were designed, and the general N nutrition diagnosis method as SPAD -502 chlorophyll meter, RQflex plus 10 nitrate reflectrom- eter and GreenSeeker - 505 spectrometer were used at eight leaf stage, tenth leaf stage and bolting stage of rape to determine the suitable nitrogen rapid diagnosis method and establish the model of yield forecast and N rate recommendation as topdressing. The experiment 2 was designed to validate the veracity of yield forecast model obtained from experiment 1. The experiment 3 was designed to test the accuracy of N rate recommendation model come from experiment 1. The results indicated that there is a preferable inter-relation between N application rates and rape yield for experiment 1 （ y = - 0. 0176x2 ＋ 11. 136x ＋797. 88 ,R2 =0. 9905 ＊ ＊ ） , which conform to the performance of yield variation with N application levels as shortage, appropriate and excessive rapeseed. For three diagnosis methods, nitrate reflectrometer could reflect rape N nutrition status to some extent, but which influenced by rapeseed physiological char-acteristics such as lower biomass at seedling stage and luxury absorption of N at bolting stage, and the re-liability and stability of diagnosis were inferior. Spectrometer is suitable for quick N nutrition diagnosis at bolting stage, but the stage of topdressing is too late to meet the demand of N support. SPAD meter could more suitable in quick N diagnosis of oilseed rapes since it could reflect rape N nutrition preferable, and it has some advantages such as the strong stability, easy measuring and lower cost in detection. By SPAD meter, model of yield forecast yforeCastyield =370. 517xSPAD value -13310.3 （x 〈42. 54） and recommended N rate yR_dedNrate =162.7-[（370.517xSPADTflliie- 13 10. 3 ）/10. 0617 - 76. 7398 ] （x〈42.54） were established. For experiment 2, the actual yield and forecast yield showed good correlation （y = 0. 5022 ＋2244. 3x, R2 =0. 7852 ＊ ） . For experiment 3 , the amount of topdressing N calculate from recommended N rate model were put forward, and the yield for different treatments had no significant difference. Total-ly ,SPAD chlorophyll meter could be used in quick N nutrition diagnosis, forecast yield and N recommen-dation of oilseed rape.

Research on Glutamate Dehydrogenase Activity in Sugar Beet (Beta vulgaris L) under Different Nitrogen Levels

The experiment of Glutamate Dehydrogenase (GDH) activity in various plant parts under different nitrogen levels in frame culture during the whole period of growth was carried out on campus of Northeast Agricltural University in 1993. The result showed that GDH activity in leaf blades under four nitrogen applied levels rose rapidly to the acme from the seedling to foliage rapid growth stage, then diminished rapidly to the lower level at the latter stage of foliage rapid growth. This level was kept to harvest. GDH activity in roots at each growth stage under all nitrogen levels exhibited little disparity and did not show ostensible regularity of changes. GDH activity in leaf blades was stimulated with nitrogen, however, it reduced with nitrogen fertilizer applying further. GDH activity in leaf blades was the biggest compared with crowns, petioles and roots, which suggested that it could represent the highest enzyme activityof the whole plant.

Nutrient and growth elucidation of a novel coated urea on oilseed rape in three main cultivation areas

A novel coated urea(MVCU)was prepared,and its application effect was verified by field trials of oilseed rape in three main cultivation areas.Meanwhile,the nutrient release and coating layer changes of MVCU in static water at 25
C and different soils were systematically evaluated.MVCU showed a long nutrient release time under static water(77 days)and soil incubation(140 days)conditions due to the slow degradation of the coating layer in MVCU,and its nitrogen release coincided well with oilseed rape nitrogen demand.The above results were further confirmed by FT-IR spectra and SEM analysis.Compared with conventional urea(U),the field trials of MVCU in the three main cultivation areas showed high nitrogen utilization efficiency and yield advantages in oilseed rape.The field trials results indicated that the MVCU significantly enhanced the aboveground dry matter(28.7%),the seed nitrogen concentration(9.5%)and aboveground nitrogen accumulation(42.5%)of oilseed rape at the mature stage as compared to that of the U.The oilseed rape yield enhanced by 932.8 kg/hm^(2),the average growth rate was 65.1%,and nitrogen utilization efficiency increased by 21.2%.In short,MVCU has the advantages of excellent slow-release performance and strong applicability,and its yield-increasing effect on oilseed rape could reach or even be better than that of traditional fertilization.

Variation of Nitrogen Uptake and Utilization Efficiency of Mid-Season Hybrid Rice at Different Ecological Sites under Different Nitrogen Application Levels

[Objective] The study aimed at investigating the effects of different geographic sites,soil chemical characteristics and nitrogen application levels on nitrogen accumulation and distribution in different organs and utilization efficiency for mid-season hybrid rice.[Method] By using mid-season rice varieties II-you 7 and Yuxiangyou203 as the experimental materials,field experiment was conducted at seven ecological sites in four provinces or cities in Southwestern China in 2009.A total of four nitrogen application levels were set as follows：by using 75 kg/hm2 of P2O5 and 75 kg/hm2 of K2O as the base fertilizer,extra 0,90,150 and 210 kg/hm2 of nitrogen fertilizer（in which,base fertilizer,base-tillering fertilizer and base-earing fertilizer respectively accounted for 60%,20% and 20%.） was applied,respectively.In the split-plot design,fertilizer was considered as the main factor while rice variety was taken as the secondary factor.A total of eight treatments were set with three replications.[Result] Highly significant differences of grain yield were found among seven locations,two varieties,four nitrogen application levels,interactions of site × variety and site × nitrogen application level,but the interaction of variety ×nitrogen application level had no significant influence on rice yield.There were highly significant effects of site,varieties and nitrogen application level on dry matter production,nitrogen content,nitrogen utilization efficiency.Highly significant negative correlations between uptake efficiency and utilization efficiency for nitrogen were found;and multiple stepwise regression analysis showed that nitrogen uptake-utilization efficiency were significantly influenced by different ecological sites,chemical quality of soil and the levels of nitrogen application.[Conclusion] The research will provide theoretical and practical basis for the highly efficient application of nitrogen in mid-season hybrid rice cultivation.

Studies on Glutamine Synthetase Activity in Sugar Beet （BetavulgarisL．） under Different Levels of Nitrogen

It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.

Response of seed tocopherols in oilseed rape to nitrogen fertilizer sources and application rates

Tocopherols （Tocs） are vital scavengers of reactive oxygen species （ROS） and important seed oil quality indicators. Nitrogen （N） is one of the most important fertilizers in promoting biomass and grain yield in crop production. However, the effect of different sources and application rates of N on seed Toc contents in oilseed rape is poorly understood. In this study, pot trials were conducted to evaluate the effect of two sources of N fertilizer （urea and ammonium nitrate）. Each source was applied to five oilseed rape genotypes （Zheshuang 72, Jiu-Er-1358, Zheshuang 758, Shiralee, and Pakola） at three different application rates （0.41 g/pot （N1）, 0.81 g/pot （N2）, and 1.20 g/pot （N3））. Results indicated that urea increased α-, y-, and total Toc （T-Toc） more than did ammonium nitrate. N3 was proven as the most efficient application rate, which yielded high contents of y-Toc and T-Toc. Highly significant correlations were observed between Toc isomers, T-Toc, and α-/y-Toc ratio. These results clearly demonstrate that N sources and application rates significantly affect seed Toc contents in oilseed rape.

Effects of Different Nitrogen Fertilizer Levels on Lodging and Yield of Rice

[Objective] This study aimed to investigate the effects of different fertilizer levels on lodging and yield of rice. [Method] A total of four treatments were designed and applied with 6, 9, 12 and 15 kg of nitrogen fertilizer, respectively. After seedling transplanting, the biological characteristics of rice at different growth stages in each treatment and the biological and economic characteristics of rice after lodging were determined for statistical analysis. [Result] Application with 15 kg of nitrogen fertilizer had significant promotion effect on the increase of rice yield; compared with the control (6 kg of nitrogen fertilizer), rice yield in three experimental treatments (9, 12 and 15 kg of nitrogen fertilizer, respectively) increased by 50.74%, 89.11% and 94.48%, respectively; lodging-resistance mechanical strengths of the three experimental treatments were 103.97%, 132.01% and 89.83% of the control, respectively; rice lodging resistance of treatment C (12 kg of nitrogen fertilizer) was the strongest, with the highest yield. [Conclusion] This study provides reference data and technical support for the rational fertilization of rice production.

Research on Glutamate Synthase Activity in Sugar Beet(Beta Vulgaris L.)under Different Levels of Nitrogen

The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.

Effects of Nitrogen Application Levels on Ammonia Volatilization and Nitrogen Utilization during Rice Growing Season

We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4＋-N in surface water, loss of ammonia through volatilization from paddy fields, rice production, nitrogen-use efficiency, and nitrogen content in the soil profile. The concentration of NH4＋-N in surface water and the amount of ammonia lost through volatilization increased with increasing nitrogen application level, and peaked at 1-3 d after nitrogen application. Less ammonia was lost via volatilization from clay soil than from sandy soil. The amounts of ammonia lost via volatilization after nitrogen application differed depending on the stage when it was applied, from the highest loss to the lowest： N application to promote tillering 〉 the first N topdressing to promote panicle initiation （applied at the last 4-leaf stage） 〉 basal fertilizer 〉 the second N topdressing to promote panicle initiation （applied at the last 2-leaf stage）. The total loss of ammonia via volatilization from clay soil was 10.49-87.06 kg/hm2, equivalent to 10.92%-21.76% of the nitrogen applied. The total loss of ammonia via volatilization from sandy soil was 11.32-102.43 kg/hm2, equivalent to 11.32%-25.61 % of the nitrogen applied. The amount of ammonia lost via volatilization and the concentration of NH4＋-N in surface water peaked simultaneously after nitrogen application; both showed maxima at the tillering stage with the ratio between them ranging from 23.76% to 33.65%. With the increase in nitrogen application level, rice production and nitrogen accumulation in plants increased, but nitrogen-use efficiency decreased. Rice production and nitrogen accumulation in plants were slightly higher in clay soil than in sandy soil. In the soil, the nitrogen content was the lowest at a depth of 40-50 cm. In any specific soil layer, the soil nitrogen content increased with increasing nitrogen application level, and the soil nitrogen content was higher in clay soil than in sandy soil. In terms of ammonia volatilization, the amount of ammonia lost via volatilization increased markedly when the nitrogen application level exceeded 250 kg/hm2 in the rice growing season. However, for rice production, a suitable nitrogen application level is approximately 300 kg/hm2. Therefore, taking the needs for high crop yields and environmental protection into account, the appropriate nitrogen application level was 250-300 kg/hm2 in these conditions.

Effects of Nitrogen Top-dressing Levels on Carbon-nitrogen Metabolism and Yield of Desmodium styracifoliumon

In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007. Some physiological indexes and yield ofD. styracifolium were compared among five nitrogen top-dressing levels （0, 37.5, 75.0, 112.5 and 150.0 kg N. hm-2）. Results showed that the nitrogen top-dressing could significantly increase the contents of chlorophyll, soluble protein, sucrose and nitrogen as well as nitrate reducase activity. However, there were no significant differences in most of these indexes under high nitrogen levels. Consistently, there was no significant difference in yield among nitrogen top-dressing levels of 75 kg N.hm-2, 112.5 kg N. hm-2 and 150 kg N-hm-2. Therefore, the optimum nitrogen top-dressing level ofD. styracifolium was 75 kg N. hm-2.

Regulation of Nitrogen on Potato under NaCl Stress

The effects of nitrogen on physiological and biochemical characteristics of potato cultivar Zihuabai under NaCl stress were studied in culture condition.The results show that,under NaCl stress,the contents of proline,chlorophyll and protein and root system vitality first increase and then decrease with the increase of nitrogen level,and reach the top under 4.17 mmol/L NH4NO3 level.Wherein,the contents of chlorophyll,protein and root system vitality are respectively 69.88%,13.07% and 59.29% higher than that of the control under 4.17 mmol/L NH4NO3 level;the activities of superoxide dismutase（SOD）and peroxidase（POD）increase generally under NaCl stress with the increase of nitrogen level,and reach the peaks [111.83 U/g and 25.467 U/（g·min）],which are 37.73% and 35.46% higher than that of control,at 6.25 mmol/L NH4NO3 level.

Effect of Corn Stalks Treated with Carbonylamines in Different Concentrate and Forage Rations and Nitrogen Conditions on Rumen Fermentation in Vitro

[ Objective] To investigate the effects of concentrate/roughage ratios and nitrogen levels on in-vitro rumen fermentation of urea-treating corn stalk. [ Method] The concentrate/roughage ratios were 7： 3, 5：5 and 3： 7. The crude protein levels were 11% and 14%. The in-vitro culture time was 2, 4, 6 and 48 h. [ Result] The pH value of broth decreased significantly with the decline in the proportion of roughage （ P 〈 0.01 ） and with the increase in the crude protein levels （P 〈 0.05）. The ammonium nitrogen concentration and acetic acid/propionic acid ratio of the fermen- ted products decreased with the increase in the crude protein levels and proportion of concentrate in diet. The diet with concentrate/roughage ratio of 5：5 and crude protein level of 14% had significantly higher digestibility of dry matter and organic matter than other diets （ P 〈 0.05）. The digesti- bility of organic matter increased gradually with the increasing proportion of concentrate and crude protein level. With the increase in the proportion of concentrate, the microbial protein levels increased remarkably, while the acetic acid/propionic acid ratio declined. [ Conclusion] The concentrate/ roughage ratios and nitrogen levels affect rumen fermentation and microbial growth during in-vitro culture. However, the best supplementary feeding results of urea-treatinq corn stalks can be obtained when the concentrate/rouahaae ratio is below 5：5 and the crude protein level is 14%.

The effects of high temperature level on square Bt protein concen-tration of Bt cotton

Higher boll worm survival rates were detected after high temperature presented during square period in Bt cotton. The objective of this study was to investigate the effects of high temperature level on the Bt efficacy of two different types of Bt cotton cultivars at squaring stage. During the 2011 to 2013 cotton growth seasons, high temperature treatments ranged from 34 to 44°C in climate chambers, and field experiments under high temperature weather with various temperature levels were conducted to investigate the effects of the high temperature level on square Bt protein concentration and nitrogen metabolism. The climate chamber experiments showed that the square insecticidal protein contents reduced after 24 h elevated temperature treatments for both cultivars, whereas significant declines of the square insecticidal protein contents were detected at temperature 〉38°C, and only slightly numerical reductions were observed when temperature below 38°C. Similar high temperature responses were also observed at the two field experimental sites in 2013. Correspondingly, high temperature below 38°C seems have little effect on the square amino acid concentrations, soluble protein contents, glutamic-pyruvic transaminase（GPT） and glutamic-oxalacetic transaminase（GOT） activities as well as protease and peptidase activities; however, when the temperature was above 38°C, reduced soluble protein contents, enhanced amino acid concentrations, decreased GPT and GOT activities, bolstered protease and peptidase activities in square were detected. In general, the higher the temperature is（〉38°C）, the larger the changes for the above compound contents and key enzymes activities of the square protein cycle. The findings indicated that the unstable insect resistance of the square was related to high temperature level during square stage.