You XU,Xuehua WANG*,Qisheng QIU,Bin SHEN

1.College of Agronomy,Hunan Agricultural University,Changsha 410128,China;

2.Hengyang Bureau of Agriculture,Hengyang 421200,China;

3.Hunan Benzhi Biotechnology Co.,Ltd,Changsha 410011,China

Responsible editor:Xiaoxue WANG Responsible proofreader:Xiaoyan WU

Photosynthesis lays foundation for growth and development of early hybrid rice and yield formation,as well as a factor deciding productivity[1].Yield of early hybrid rice,co-contributed by yield components,is decided by Photosynthetic material production capacity and operation and distribution of photosynthetic assimilation products[2].The process of early hybrid rice yielding is actually a process of accumulation and distribution of dry matters,and 90%-95% of the increases of dry matter are from photosynthesis of leaf[3].What’s more,any physiological metabolism,which improves photosynthetic efficiency of rice groups and net photosynthetic rate of leaf area per unit area,extending leaf photosynthetic period,accelerating transportation and distribution of photosynthate,and increasing storage of starch,would all enhance rice yield[4-5].

Currently,highly-qualified early hybrid rice applied in production performs not so satisfied in some areas in terms of yield,disease or lodging resistance,due to climate,soil and management differences[6].It is key for stabilization and improvement of total yield of early hybrid rice to increase yield per unit area,which can be accomplished by enhancing photosynthetic capacity and efficiency for solar energy utilization."Yezhiyuan",a photosynthesis synergist developed by Hunan Benzhi Biotechnology Co.Ltd.,proves well in improving the content of chlorophyll in functional leaf and photosynthetic rate,reducing transpiration rate,and increasing yield per unit area[7-9].In order to further demonstrate the effects of Yezhiyuyan in early hybrid rice in Hunan,a test was conducted in farmlands in Yunyuan Teaching and Testing Base of Hunan Agricultural University and Meihua Village,Xidu Town,Hengyang County,National Crop Yielding S&T Engineering Demonstration,which provides references for extension of Yezhiyuan in other areas.

Materials and Methods

Materials

The test was conducted in farmlands in Yunyuan Teaching and Testing Base of Hunan Agricultural University and Meihua Village,Xidu Town,Hengyang County,National Crop Yielding S&T Engineering Demonstration.In Hunan Agricultural University,the test material was Lingliangyou No.211,and test material was Lingliangyou No.268 in Hengyang.Both test materials were provided by Longping Seed,and Yezhiyuan was supplied by Hunan Benzhi Biotechnology Co.Ltd.

Methods

Test designThe test was conducted in experimental sites in Hunan Agricultural University and Hengyang,respectively,with two treatments.Specifically,treatment 1 involved Yezhiyuan of 450 g/hm2(×1 000) and treatment 2 was a control(CK).The test was conducted as per randomized block design,with three repetitions,and the test region totaled 13.3 m2.At first,rice in the test plots were sprayed in the end of tillering stage in treatment 1 and rice in treatment 2 was not sprayed.Subsequently,seedlings were sprayed at 16:00 in a sunny day and rice should be covered with films,avoiding spraying to other test plots.On March 30,2012,seeds were sown and transplanted on May 2 at 16.7 cm×20 cm.On June 15,Yezhiyuan was sprayed and transplanting should be conducted in a field with shallow water.Other preventions of disease and insect damages were conducted as per local highly-qualified fields.

Measured itemsThe number of tiller was surveyed once every 3 d after turning green to record basic seedlings; photosynthetic rate and transpiration rate were measured on June 30 with photosynthesis equipment (LI6400) of two leaves in every test plot to get an average; the content of chlorophyll of the 1stleaf in upper part was measured on July 8 with a portable chlorophyll instrument(HK/SPAD-502Plus) and the leaves with similar values were averaged; in ripening stage,the number of productive ear in surveyed areas was measured and rice samples were collected from 5 holes in every test plot to explore seeds and compute theoretical yield; rice was harvested in different test plots to measure practical yield.

Data processingThe test data were settled and analyzed with Excel and DPS.

Results and Analysis

Photosynthetic rate

As shown in Table1,photosynthetic rate of flag-leaf reached 16.96 μmol/(m2·s) in treatment 1 in Hunan Agricultural University,which was significantly higher than that of control; in Hengyang,the photosynthetic rate reached 14.34 μmol/(m2·s),accordingly,which was also higher compared with control.It is obvious that Yezhiyuan would improve photosynthetic rate in the same term.

Transpiration rate

Transpiration is the process of water movement through a plant,accelerating transportation rate of inorganic salt to ground parts and reducing plant temperature,which prevents leaves from hurt by photosynthesis.Nevertheless,self-grown green plants have to exchange gases with surroundings at photosynthesis,so that water in plants would lose upon water potential gradient.Hence,it is necessary to inhibit transpiration properly and reduce water consumption to promote plant growth.As shown in Table2,in the experimental site in Hunan Agricultural University,transpiration rate of flag-leaf was 8.73 g/(m2·h),which was lower compared with control group,showing little differences.In Hengyang experimental site,the transpiration rate of flag-leaf reached 9.77 g/(m2·h),which was lower than that of control,showing insignificant differences.In the two sites,although the differences between treatments were not so significant,transpiration rate in the treatment sprayed with Yezhiyuan kept declining,suggesting that Yezhiyuan would reduce transpiration rate of early hybrid rice in the same term.

The content of chlorophyll

The content and components of chlorophyll have significant effects on photosynthesis and high content of chlorophyll relies on photosynthesis of leaf in later stage.Therefore,a highcontent of chlorophyll in later period would enhance rice yield.As shown in Table3,the content of chlorophyll in experimental site in Hunan Agricultural University was 44.57,which was higher than that of control,showing significant differences.In Hengyang experimental site,in contrast,the content of chlorophyll reached 42.59,which was higher compared with control,also showing significant differences.It can be concluded that Yezhiyuan would increase the content of chlorophyll of early hybrid rice in the same term.

Table1 The effect of Yezhiyuan photosynthesis synergist on photosynthetic rate μmol/m2·s

Table2 The effects of Yezhiyuan photosynthesis synergist on transpiration rate g/m2·h

Table3 The effect of Yezhiyuan photosynthesis synergist on SPAD

Table4 The effect of Yezhiyuan photosynthesis synergist on yield per unit area kg

Table5 The effect of Yezhiyuan photosynthesis synergist on rice theoretical yield and its influence factors

Yield

In treatment 1 in Hunan Agricultural University,rice yiled was 8.64 kg,which was 8.54% higher compared with control group,showing significant differences.In contrast,in treatment 1 in Hengyang experimental site,rice yield was 7.78 kg,which was 10.67%higher compared with control,showing significant differences.It can be concluded that Yezhiyuan would increase yield of early hybrid rice in the same term(Table4).

Yield component factors

The yield of early hybrid rice is determined by the number of ear per unit area,the number of kernel per ear,setting percentage and thousandseed weight.It can be concluded from Table5 that after application of Yezhiyuan,both of setting percentage and thousand-seed weight increased,and theoretical yield grew considerably.Furthermore,the theoretical yield in Hunan Agricultural University increased by 4.76% in Hunan Agricultural University compared with control and 2.96% in Hengyang experimental site.

Conclusions and Discussions

The test showed that with Yezhiyuan applied in the end of tillering stage,photosynthetic rate and yield of Lingliangyou No.211 and Lingliangyou No.268 were both higher compared with control group,which indicated that Yezhiyuan would improve photosynthetic rate and yield.Meanwhile,considering from SPAD,it can be concluded that Yezhiyuan would increase the relative content of early hybrid rice,possibly caused by the reduced degradation rate of chlorophyll and extended photosynthesis after Yezhiyuan was applied,which actually provides abundant photosynthate and is conductive to growth of early hybrid rice.However,the application effect of Yezhiyuan is definitely under influence of climate,soil fertility,and crop variety.In future,therefore,further attention should be paid to application term,concentration,and times of Yezhiyuan in order to precisely understand the work mechanism and provide more accurate references for its application.

[1]PAN RC (潘瑞熾).Plant physiology(the 5th edition)(植物生理學(xué) (第五版))[M].Beijing:Higher Education Press (北京:高等教育出版社),2005.

[2]LV J(呂 軍),WANG BL(王伯倫),MENG WR (孟維韌),et al.The characteristics of photosynthesis and dry matter production in japonica rice cultivars with different type panicles (不同穗型粳稻的光合作用與物質(zhì)生產(chǎn)特性)[J].Scientia Agricultura Sinica (中國(guó)農(nóng)業(yè)科學(xué)),2007,(5):902-908.

[3]WANG W(王 衛(wèi)),XIE XL(謝小立),XIE YH (謝永宏).Key factors of high yields of early hybrid rice and its mechanism(雜交早稻高產(chǎn)的關(guān)鍵因子及其作用機(jī)理)[J].Hunan Agricultural Sciences (湖南農(nóng)業(yè)科學(xué)),2010,(5):42-46,49.

[4]GAO Y(高 宇),TIAN T(田 恬).Research progress on physiological breeding of super-high yielding early hybrid rice (超高產(chǎn)雜交早稻生理育種研究進(jìn)展)[J].Chinese Agricultural Science Bulletin(中國(guó)農(nóng)學(xué)通報(bào)),2004,(3):1-3.

[5]WANG SX(王少先),PENG KQ(彭克勤),XIAO LT(蕭浪濤),et al.The application and mechanism of synergist for early hybrid rice(雜交早稻專用配方肥增效劑的應(yīng)用及其作用機(jī)理研究)[J].Plant Nutrition and Fertilizer Science (植物營(yíng)養(yǎng)與肥料學(xué)報(bào)),2003,(3):294-298.

[6]NIU ZG(牛兆國(guó)).Production and development strategies of highly-qualified early hybrid rice in China(我國(guó)優(yōu)質(zhì)雜交早稻生產(chǎn)現(xiàn)狀及發(fā)展對(duì)策)[J].Modern Agricultural Science and Technology(現(xiàn)代農(nóng)業(yè)科技),2010,(23):343-344,347.

[7]WANG BF (汪本福),HUANG JP (黃金鵬),JIANG S (姜 仕),et al.Effect of“Yezhiyuan” photosynthesis biological synergist applied on rice(作用生物增效劑在雜交早稻上的應(yīng)用效果研究)[J].Hubei Agricultural Sciences(湖北農(nóng)業(yè)科學(xué)),2012,(11):2180-2183.

[8]MEI ZD(梅正鼎),LI RL(李瑞蓮),HE YX(賀云新),et al.Influences of photosynthesis biological synergist on growth,yield and quality of cotton(光合作用生物增效劑對(duì)棉花生長(zhǎng)及產(chǎn)質(zhì)量的影響)[J].Hunan Agricultural Sciences (湖南農(nóng)業(yè)科學(xué)),2012,(19):34-36.

[9]LU CD(盧成達(dá)),GUO ZL(郭志利),Li Y(李 陽(yáng)),et al.Application effects of two photosynthesis synergists on millets(兩種光合增效劑在谷子上的應(yīng)用效果研究)[J].Bulletin of Agricultural Science and Technology (農(nóng)業(yè)科技通訊),2013,(9):33-35.