Effects of Nutrient Solution pH on the Growth of Seedlings of Sugarcane

Liping ZHAO,Jiayong LIU*,Peifang ZHAO,Fenggang ZAN,Jun ZHAO,Kun YANG,Caiwen WU,Xuekuan CHEN

1.Sugarcane Research Institute,Yunnan Academy of Agricultural Sciences,Kaiyuan 661699,China;

2.Yunnan Province Key Laboratory of Sugarcane Genetic Improvement,Kaiyuan 661699,China

Responsible editor:Xiaoxue WANG Responsible proofreader:Xiaoyan WU

Soil pH plays a key role in plant growth which will be adversely affected by inappropriate pH.In China,pH of soil tends to be volatile from south to north,and pH generally keeps acid over 81%[1].Furthermore,the soils with pH below 5.5 account for 62%.For example,arithmetic mean value and geometric mean of soil pH of sugarcane-producing areas are 4.35 and 4.34[2]in Liangjiang Town,Xingbin District,Guangxi Province.Hence,it is extremely strong acid soils.Although sugarcane is tolerant to soil infertility and acidity,excessive acidity would reduce use rate of P fertilizers and affect sugarcane root growth,decreasing yield[1].Currently,the researches available are mainly on wheat,rice,tobacco and peanut,in terms of relationship between biological activity and pH value[3-10].Less attention is paid to the effects of pH on seedling root growth of sugarcane[11].The research explored the effects of nutrient solutions with different pH values on biomass,root shape,root activity,stem diameter and plant height of seedlings in order to select the sugarcane varieties and the most suitable pH environment for sugarcane growth.

Materials and Methods

Materials

The hybrid generations of RB85-5156×Yunrui 05-407,Yunrui 06-3501×Tolodo,Yuetang 94-128×Ganzhe 75-65,ROC6 ×Yunrui 05-733,VMC87-95×Yunrui 05-171 were taken as materials,recorded as A,B,C,D,and E,respectively.

Methods

The hybrid seeds were sown in June 2012 in a greenhouse,Sugarcane Research Institute,Yunnan Academy of Agricultural Sciences.Then,seedlings of the 5 treatments were sampled randomly and cultivated as per local method.When 4-5 leaves of seedlings grew,the seedling growing similarly can be transplanted to a pot where substrates were river sands washed clean.After the transplanting,the seedlings were irrigated with running water and then treated with nutrient solutions with the seedlings matured.Specifically,pH was set at 5.0,7.0 and 8.5 and every treatment was with three repetitions,namely,3 pots were involved of every pH value for each hybrid seed treatment.It is notable that every pot was with a repetition at 15 plants per pot (height at 32 cm and diameter at 35 cm).The value of pH was measured with a pH meter(pH-3C) and the value of pH was adjusted to the ruled one with 1 mol/L H2SO4and 1 mol/L NaOH.The nutrient solution was Hoagland’s solution and seedlings were irrigated weekly.After the plant grew for 130 d,biomass,plant height,stem diameter,root shape,and root activity were measured accordingly.

Measurement index and methods

According to measurements of root system,a complete plant was collected from a cultivation pot and washed clean with running water.Subsequently,the clean seedlings were removed from a plant and surface water was dried with absorbent paper.The seedlings were then separated as per simple root and placed side by side on a specific root tray.The root system was then scanned with a Win-RHIZO LA6400XL and the scanned pictures were stored in different folders as per plant number,repetition,and classification.Then,total root length,root surface area,average diameter of root system,root volume and root length with different diameters were computed with a WinRHIZO.

Stem diameter and plant height were measured as per local method.

Biomass was measured as follows:Ground seedlings and roots were cleaned with running water and water was absorbed with absorbent paper to measure the weight.Then,the seedlings were killed out at 105 ℃for 0.5 h and dried to a constant weight at 70 ℃to measure the dry weight.

Root activity was measured as per TTC method[12].Specifically,the root tip was collected at 0.5 g and added with 0.4% TTC at 0.2 ml and 1/15 PBS at 5 ml,which was stored for 1 h in dark at 37 ℃.Then,1 mol/L H2SO4was added to end the reaction.The materials were then collected to dry with filter paper,added with ethyl acetate,followed by grinding.The red extracting solution was collected and solution was fixed to a constant volume at 10 ml with ethyl acetate.The reduction quantity (C) of TTC was measured with a spectrophotometer at 485 nm.

The root activity=C/(Wt×1 000),which C refers to the reduction quantity of tetrazole (μg/(g·h)),W refers to root mass (g),and t represents the reaction time(h).

Data processing

The test data were analyzed with SPSS 18.0 and Excel 2003.

Results and Analysis

Effects of pH treatments on seedling growth during seedling period

Effects on biomasses of root system and ground part of plantsAs shown in Table1,with pH at 8.5,fresh weight and dry weight of plant and root system in treatments A and D,as well as dry weight of plant and root system in treatment B,maintained higher compared with the treatment with pH at 5.0.In treatment E,the differences of biomass showed none statistical significance with Ph designed at three levels.It can be concluded that the value of pH at 5.0 has inhibition on seedling biomass accumulation.

Effects on morphological characteristics of root systemAs shown in Table2,morphological characteristics of root system changed dramatically in the five treatments and total root length,surface root area,root diameter and root volume in treatments A,C and D all reached the lowest with pH value at 7.0,and the highest with pH value at 8.5,when total root length,surface root area,and root volume were all significantly higher compared with the treatment with pH at 5.0.With pH at 7.0,except of root diameter,the rest characteristics of root system were all higher compared with the treatments with pH values at 5.0 and 8.5.In addition,for pH value at 8.5,total root length and surface root area ofthe seedlings were both higher compared with the treatments with pH at 5.0.It can be concluded that the effects of nutrient solution with pH value are of none statistical significance.

Table1 The biomasses of seedlings from three pH levels g

Table2 Root morphological features of seedlings from three pH levels

Effects on root activityAs shown in Fig.1,root activity of seedlings in treatment A was increasing upon pH,and reached the peak with pH value at 8.5; in treatment B,root activity changed from increasing to decreasing upon pH and achieved the peak at 316.04 μg/(g·h) with pH value at 7.0;in treatment C,root activity changed from substantial decrease to slow growth upon pH value,and the activity with pH value at 5.0 was significantly higher at 1 009.31 μg/(g·h) compared with rest treatments; in treatment D and E,root activity was decreasing as pH value enhanced,and the activity performed significantly higher with pH of 5.0 compared with the treatment with pH of 8.5.Of the 5 treatments,root activity achieved the peak with pH value at 5.0 in treatments C,D and E,and in treatments C and E with pH value at 5.0,root activity proved the highest.

Effects on stem diameterAs shown in Fig.2,stem diameter changed insignificantly with varying pH values.Specifically,stem diameters in treatments A,B,C and D all changed from increasing to decreasing; the stem diameter in treatment A with pH of 7.0 was significantly higher compared with the treatments with pH of 5.0; the stem diameter in treatment E changed from decreasing to increasing.

Table3 Root length of seedling at different diameters from three pH levels

Effects on plant heightAs shown in Fig.3,plant heights in treatments A,B,C,and D all reached the highest with pH of 8.5 and plant height was significantly higher in treatment C with pH of 8.5,compared with that with pH of 5.0; in treatment B,plant height changed from decreasing to increasing and increasing to decreasing in treatment E.

Effects on root lengthIt can be concluded from Table3 that the root with diameter below or equal to 1.0 mm was longer,and the range of root length in treatments A and C with pH of 8.5 was significantly larger compared with that with pH of 5.0 and 7.0;in treatment B,root length in the treatment B with pH of 7.0 was far higher compared with that with pH of 5.0 and 8.5; in treatment E,differences of diameter with pH values in treatment E showed none statistical significance,except of the diameter over 4.5 mm.

Conclusions and Discussions

Water,salt and P stress all have considerable effects on plant and root system growth[13-17].Li et al.[18]researched root system shape and root activity and the results indicated that as pH increased,growth of different plants was inhibited in varying degrees and biomasses of root and ground part both dropped substantially; the inhibition proved higher of ground part[18].The research incorporated that the accumulated biomass was more in the treatment with pH of 8.5; the values of pH at 7.0 and 8.5 were conductive for seedling growth;the value of pH at 5.0 was adverse for seedling growth.

[1]GUO JW (郭家文),LIU SC (劉少春),ZHANG YB (張躍彬),et al.Distribution of Soil pH and Total N,P,K in Main Sugarcane Fields in Yunnan Provinc(云南甘蔗主產(chǎn)區(qū)土壤pH、全氮磷鉀的分布狀況)[J].Soils(土壤),2012(5):868-872.

[2]RAO J (饒江),GU MH (顧明華),SHEN FK (沈方科),et al.Spatial variation of pH,secondary and trace elements in red soils in sugarcane fields (紅壤甘蔗地土壤pH 及中、微量元素含量空間變異研究)[J].Chinese Journal of Soil Science(土壤通報(bào)),2009(4):795-799.

[3]LI QF(李清芳),XIN TR(辛天蓉),MA CC(馬成倉(cāng)),et al.Effects of pH value on wheat seed germination and seedlings growth and metabolism(pH對(duì)小麥種子萌發(fā)和幼苗生長(zhǎng)代謝的影響)[J].Journal of Anhui Agricultural Sciences(安徽農(nóng)業(yè)科學(xué)),2003,31(2):185-187.

[4]QUAN SH(全松華),WANG YG(汪永國(guó)),LUO SQ (羅紹球),et al.Effects of the pH value of bed soil in seedling quality in rice (苗床土壤pH對(duì)水稻秧苗素質(zhì)的影響)[J].Hybrid Rice (雜交水稻),2004,19(4):45-46.

[5]LIU SH (劉少華),XIE PF (謝鵬飛),XU GH(徐國(guó)華),et al.Effects of root pH on highly-yielding hybrid rice in terms of growth characters of root system (根際pH對(duì)高產(chǎn)雜交稻幼苗根系生長(zhǎng)特性的影響[J].Jiangsu Agricultural Sciences(江蘇農(nóng)業(yè)科學(xué)),2013(1):70-72.

[6]CHEN JJ (陳建軍),REN YH (任永浩),HAN JF (韓錦峰).Effects of pH of roots on tobacco root growth(根際pH值對(duì)煙草根系生長(zhǎng)的影響 (簡(jiǎn)報(bào)))[J].Plant Physiology Journal (植物生理學(xué)通訊),1993,29(1):34-37.

[7]MENG QL (孟慶玲),CHENG ZH (程智慧),XU P(徐鵬),et al.Effects of nutrient solution pH value on growth and physiological characteristics of Gerbera jamesonii Bolus(營(yíng)養(yǎng)液pH對(duì)非洲菊生長(zhǎng)和生理特征的影響)[J].Acta Botanica Boreali-Occidentalia Sinica(西北植物學(xué)報(bào)),2010(10):2081-2086.

[8]JIANG AF(蔣愛(ài)鳳),CHEN CL(陳翠玲),REN XJ (任秀娟),et al.Influence of soil pH on the root pH and growth of peanut seedlings (土壤pH對(duì)花生幼苗期根系pH 及其生長(zhǎng)狀況的影響)[J].Journal of Henan Agricultural Sciences (河南農(nóng)業(yè)科學(xué)),2006(7):51-52.

[9]XU XY (徐曉燕),SUN WS (孫五三),LI ZH (李章海),et al.Synthesis of nicotine of tobacco roots and effects of pH values on the roots growth and quality of tobacco(烤煙根系合成煙堿的能力及pH對(duì)其根系和品質(zhì)的影響)[J].Journal of Anhui Agricultural University (安徽農(nóng)業(yè)大學(xué)學(xué)報(bào)),2004(3):315-319.

[10]ZHANG X(張旭),LIU YZ(劉彥卓).Effects of soil pH on quality of doublecropping rice in southern part of China(土壤pH對(duì)華南雙季稻旱育秧素質(zhì)的影響試驗(yàn)初報(bào))[J].Guangdong Agricultural Sciences(廣東農(nóng)業(yè)科學(xué)),1998(2):8-10.

[11]LIU GL (劉光玲),CHEN RF (陳榮發(fā)),TIAN FQ (田富橋),et al.Effects of different values on growth and physiological characteristics of sugarcane seedlings (不同pH對(duì)甘蔗幼苗生長(zhǎng)和生理特性的影響)[J].Journal of Southern Agriculture (南方農(nóng)業(yè)學(xué)報(bào)),2011(4):380-383.

[12]ZOU Q(鄒琦).Guidance of plant biological tests (植物生理學(xué)試驗(yàn)指導(dǎo))[M].Beijing:China Agriculture Press(北京:中國(guó)農(nóng)業(yè)出版社),2000:62-63.

[13]YI LP(弋良朋),MA J(馬健),Li Y(李彥).The comparisons of root system and root hair morphological characteristics among three desert halophytes(3種荒漠鹽生植物根系及根毛形態(tài)特征的比較研究)[J].植物研究,2007,27(2):204-211.

[14]HAN XY(韓希英),SONG FB(宋鳳斌).Effect of drought stress on root growth and rhizosphere nutrient of maize(干旱脅迫對(duì)玉米根系生長(zhǎng)及根際養(yǎng)分的影響)[J].Journal of Soil and Water Conservation(水土保持學(xué)報(bào)),2006,20(3):170-172.

[15]MIAO HX(苗海霞),SUN MG(孫明高),XIA Y(夏陽(yáng)),et al.Effects of salt stress on root activity of Melia azedarach seedlings(鹽脅迫對(duì)苦楝根系活力的影響)[J].Journal of Shandong Agricultural University(Natural Science)(山東農(nóng)業(yè)大學(xué)學(xué)報(bào):自然科學(xué)版),2005,36(1):9-12.

[16]LI HM (李慧明),GAO ZQ (高志強(qiáng)),ZHANG YQ(張永清),et al.The biological response of root system of different genotypes spring wheat to low phosphorus stress(不同基因型春小麥根系對(duì)低磷脅迫的生物學(xué)響應(yīng))[J].Journal of Shanxi Agricultural University(Natural Science?Edition)(山西農(nóng)業(yè)大學(xué)學(xué)報(bào):自然科學(xué)版),2006,26(2):138-140.

[17]HUANG H(黃沆),CHEN GH(陳光輝).Status and prospect of research on rice root breeding (水稻根系育種的研究現(xiàn)狀及展望)[J].Journal of Hunan Agricultural University (Natural Sciences)(湖南農(nóng)業(yè)大學(xué)學(xué)報(bào):自然科學(xué)版),2009,35(1):35-39.

[18]LI CJ(李從娟),MA J(馬健),LI Y(李彥),et al.Effects of pH value on the morphological features and activity of roots of three life-form plant species(pH對(duì)3種生活型植物根系形態(tài)及活力的影響)[J].Arid Zone Research (干旱區(qū)研究),2010,27(6):915-920.