Welcome to Acta Agronomica Sinica,

Acta Agron Sin ›› 2017, Vol. 43 ›› Issue (10): 1548-1558.doi: 10.3724/SP.J.1006.2017.01548

• TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY • Previous Articles     Next Articles

Response of Endosperm Cell Proliferation and Grain Yield of Summer Maize to Different Light Conditions

GAO Jia,SHI Jian-Guo,DONG Shu-Ting,LIU Peng,ZHAO Bin,ZHANG Ji-Wang*   

  1. State Key Laboratory of Crop Biology /Agronomy College of Shandong Agricultural University, Tai’an 271018, China
  • Received:2016-12-06 Revised:2017-05-10 Online:2017-10-12 Published:2017-05-22
  • Contact: 张吉旺, E-mail: jwzhang@sdau.edu.cn, Tel: 0538-8241485 E-mail:gaoj0803@163.com
  • Supported by:

    This study was funded by National Natural Science Funds (31671629), the China Agriculture Research System (CARS-02-20), Shandong Key Agricultural Technology Innovation Project and Shandong Provincial Key Laboratory of Corn Breeding and Cultivation Technology.

Abstract:

During the period from 2012 to 2014, Zhengdan 958 (ZD958) and Denghai 605 (DH605) were used with five treatments in a randomized complete block design with three replicates, including increasing light (L) from tassel stage (VT) to maturity stage (R6) and three shading treatments (40% of ambient light intensity) from VT to R6 (S1), from the sixth leaf stage (V6) to VT (S2), and from emergence stage (VE) to R6 (S3), and natural lighting in the field (CK). The illumination intensity of L on cloudy day was 1600?1800 μmol m-2 s-1. This experiment was conducted to explore the effects of light on endosperm cell proliferation, grain filling, starch content, dry matter accumulation and yield of summer maize. The dry matter accumulation of embryo and endosperm was significantly decreased under shading, as well as the content of starch and the endosperm cell plumpness decreased also. Effect of S3 on endosperm cell proliferation was the most, while that of S2 was the smallest. At R6, the endosperm cells number of S3, S2, S1 decreased by 33%, 6%, 29% in ZD958 and 41%, 5%, 29% in DH605. The dry matter accumulation of embryo and endosperm as well as the content of starch and the endosperm cell plumpness were increased after increasing light. The grain filling rate decreased and the days to maximum grain filling rate postponed under shading, while those increased after increasing light. The maximum grain filling rate of S1, S2, S3 decreased by 34%, 13%, 58% in ZD958 and 38%, 13%, 64% in DH605. The grain yield of S1, S2, S3 decreased by 58%, 26%, 81% in ZD958 and 67%, 27%, 81% in DH605. Results indicate that the number of endosperm cells, starch content and grain filling rate are decreased under shading, resulting in grain yield reducing, while L treatment can contribute to increasing the number of endosperm cell and grain yield.

Key words: Summer maize, Illumination, Endosperm cell proliferation, Grain filling, Grain yield

[1]贾士芳, 李从锋, 董树亭, 张吉旺. 花后不同时期遮光对玉米粒重及品质影响的细胞学研究. 中国农业科学, 2010, 43: 911–921 Jia S F, Li C F, Dong S T, Zhang J W. Effects of shading at different stages after anthesis on maize grain weight and quality at cytology level. Sci Agric Sin, 2010, 43: 911–921 (in Chinese with English abstract) [2]秦大鹏, 刘鹏, 王空军, 董树亭, 张吉旺, 刘月娥. 高淀粉玉米籽粒胚乳细胞增殖与淀粉积累的关系. 山东农业科学, 2008, (8): 35–39 Qin D P, Liu P, Wang K J, Dong S T, Zhang J W, Liu Y E. Relationship between endosperm cell proliferation and starch accumulation in high-starch maize grain. Shandong J Agric Sin, 2008, (8): 35–39 (in Chinese with English abstract) [3]徐云姬, 顾道健, 张博博, 张耗, 王志琴, 杨建昌. 玉米果穗不同部位籽粒激素含量及其与胚乳发育和籽粒灌浆的关系. 作物学报, 2013, 39: 1452–1461 Xu Y J, Gu D J, Zhang B B, Zhang H, Wang Z Q, Yang J C. Hormone contents in kernels at different positions on an ear and their relationship with endosperm development and kernel filling in maize. Acta Agron Sin, 2013, 39: 1452–1461 (in Chinese with English abstract) [4]孙庆泉, 吴元奇, 胡昌浩, 董树亭, 荣廷昭, 张颖. 不同产量潜力玉米籽粒胚乳细胞增殖与籽粒充实期的生理活性. 作物学报, 2005, 31: 612–618 Sun Q Q, Wu Y Q, Hu C H, Dong S T, Rong T Z, Zhang Y. Physiological activities and multiplication of endosperm cell at filling stage of kernels with different yield in maize. Acta Agron Sin, 2005, 31: 612–618 (in Chinese with English abstract) [5]Zhao L, Pan T, Cai C, Wang J, Wei C. Application of whole sections of mature cereal seeds to visualize the morphology of endosperm cell and starch and the distribution of storage protein. J Cereal Sci, 2016, 71: 19–27 [6]张智猛, 戴良香, 胡昌浩, 董树亭, 王空军, 宁堂原. 玉米灌浆期水分差异供应对籽粒淀粉积累及其酶活性的影响. 植物生态学报, 2005, 29: 636–643 Zhang Z M, Dai L X, Hu C H, Dong S T, Wang K J, Ning T Y. Effects of different water treatments on starch accumulation and related enzyme activity in grain filling period. Chin J Plant Ecol, 2005, 29: 636–643 (in Chinese with English abstract) [7]谷岩, 王振民, 何文安, 梁烜赫, 吴春胜. 不同类型玉米品种籽粒胚乳细胞增殖与籽粒建成的关系. 西北农林科技大学学报, 2010, 38(1): 90–96 Gu Y, Wang Z M, He W A, Liang X H, Wu C S. Relationship between endosperm cell proliferation and seed formation in maize of different types. J Northwest A&F Univ, 2010, 38(1): 90–96 (in Chinese with English abstract) [8]李栋梁, 李小刚, 顾蕴洁, 王忠. 不同类型水稻品种胚乳发育的研究. 中国农业科学, 2014, 47: 3757–3768 Li D L, Li X G, Gu Y J, Wang Z. Investigation of endosperm cell development of different rice varieties. Sci Agric Sin, 2014, 47: 3757–3768 (in Chinese with English abstract) [9]王贺正, 马均, 李旭毅, 张荣萍. 水分胁迫对水稻籽粒灌浆及淀粉合成有关酶活性的影响. 中国农业科学, 2009, 42: 1550–1558 Wang H Z, Ma J, Li X Y, Zhang R P. Effects of water stress on grain filling and activities of enzymes involved in starch synthesis in rice. Sci Agric Sin, 2009, 42: 1550–1558 (in Chinese with English abstract) [10]李伯航, 崔彦宏. 夏玉米胚乳细胞建成与粒重关系. 河北农业大学学报, 1989, 12(4): 39–45 Li B H, Cui Y H. Studies on the relationship between endosperm cell development and kernel weight of summer maize. J Agric Univ Hebei, 1989, 12(4): 39–45 (in Chinese with English abstract) [11]杜成凤, 李潮海, 刘天学, 赵亚丽. 遮阴对两个基因型玉米叶片解剖结构及光合特性的影响. 生态学报, 2011, 31: 6633–6640 Du C F, Li C H, Liu T X, Zhao Y L. Response of anatomical structure and photosynthetic characteristics to low light stress in leaves of different maize genotypes. Acta Ecol Sin, 2011, 31: 6633–6640 (in Chinese with English abstract) [12]史建国, 朱昆仑, 曹慧英, 董树亭, 刘鹏, 赵斌, 张吉旺. 花粒期光照对夏玉米干物质积累和养分吸收的影响. 应用生态学报, 2015, 26: 46–52 Shi J G, Zhu K L, Cui H Y, Zhao B, Dong S T, Liu P, Zhang J W. Effect of light from flowering to maturity stage on dry matter accumulation and nutrient absorption of summer maize. Chin J Appl Ecol, 2015, 26: 46–52 (in Chinese with English abstract) [13]曾希柏. 作物生长中光照和氮肥施用量的相互关系研究. 土壤学报, 2008, 37: 380–386 Zeng X B. Research on the correlation of light and nitrogen application in crop growth. Acta Pedol Sin, 2008, 37: 380–386 (in Chinese with English abstract) [14]Ren B Z, Cui H Y, James J C, Dong S T, Liu P, Zhang J W. Effects of shading on the photosynthetic characteristics and mesophyll cell ultrastructure of summer maize. Sci Nat, 2016, 103: 67 [15]崔海岩, 靳立斌, 李波, 赵斌, 董树亭, 刘鹏, 张吉旺. 大田遮阴对夏玉米光合特性和叶黄素循环的影响. 作物学报, 2013, 39: 478–485 Cui H Y, Jin L B, Li B, Zhao B, Dong S T, Liu P, Zhang J W. Effects of shading on photosynthetic characteristics and xanthophyll cycle of summer maize in the field. Acta Agron Sin, 2013, 39: 478–485 (in Chinese with English abstract) [16]张吉旺, 董树亭, 王空军, 胡昌浩, 刘鹏. 遮阴对夏玉米生长发育和产量的影响. 应用生态学报, 2006, 17: 657–662 Zhang J W, Dong S T, Wang K J, Hu C H, Liu P. Effects of shading on the growth, development and grain yield of summer maize. Chin J Appl Ecol, 2006, 17: 657–662 (in Chinese with English abstract) [17]王洋, 齐晓宁, 邵金锋, 刘兆永, 李泽兴. 光照强度对不同玉米品种生长发育和产量构成的影响. 吉林农业大学学报, 2008, 30: 769–773 Wang Y, Qi X N, Shao J F, Liu Z Y, Li Z X. Effects of light intensity at full growing stage on the growth and yield of different maize varieties. J Jilin Agric Univ, 2008, 30: 769–773 (in Chinese with English abstract) [18]付景, 李潮海, 赵久然, 马丽, 刘天学. 玉米品种耐阴性指标的筛选与评价. 应用生态学报, 2009, 20: 2705–2709 Fu J, Li C H, Zhao J R, Ma L, Liu T X. Shade-tolerance indices of maize: Selection and evaluation. Chin J Appl Ecol, 2009, 20: 2705–2709 (in Chinese with English abstract) [19]王秀萍, 刘天学, 李潮海, 李大鹏. 遮光对不同株型玉米品种农艺性状和果穗发育的影响. 江西农业学报, 2010, 22(1): 5–7 ang X P, Liu T X, Li C H, Li D P. Effects of shading on agronomic traits and ear development of maize cultivars (Zea mays L.) with different plant types. Acta Agric Jiangxi, 2010, 22(1): 5–7 (in Chinese with English abstract) [20]Ma B L, Morrison M J, Dwyer L M. Canopy light reflectance and field greenness to assess nitrogen fertilization and yield of maize. Agron J, 1996, 88: 915–920 [21]刘仲发, 勾玲, 赵明, 张保军. 遮阴对玉米茎秆形态特征、穿刺强度及抗倒伏能力的影响. 华北农学报, 2011, 26(4): 91–96 Liu Z F, Gou L, Zhao M, Zhang B J. Effects of shading on stalk morphological characteristics, rind penetration strength and lodging-resistance of maize. Acta Agric Boreali-Sin, 2011, 26(4): 91–96 (in Chinese with English abstract) [22]贾士芳, 董树亭, 王空军, 张吉旺, 刘鹏. 弱光胁迫对玉米产量及光合特性的影响. 应用生态学报, 2007, 18: 2456–2461 Jia S F, Dong S T, Wang K J, Zhang J W, Liu P. Effects of weak light stress on grain yield and photosynthetic traits of maize. Chin J Appl Ecol, 2007, 18: 2456–2461 (in Chinese with English abstract) [23]Hashemi-Dezfouli A, Herbert S J. Intensifying plant density response of corn with artificial shade. Agron J, 1992, 84: 547–551 [24]张亚勤, 杨华, 祁志云, 袁亮, 王楠, 金川, 邱正高. 遮光胁迫对玉米植株性状的影响研究. 中国农学通报, 2011, 27(33): 40–43 Zhang Y Q, Yang H, Qi Z Y, Yuan L, Wang N, Jin C, Qiu Z G. Effect of light stress on the plants characters of maize inbred lines. Chin Agric Sci Bull, 2011, 27(33): 40–43 (in Chinese with English abstract) [25]贾士芳, 董树亭, 王空军, 张吉旺, 刘鹏. 玉米花粒期不同阶段遮光对籽粒品质的影响. 作物学报, 2007, 33: 1960–1967 Jia S F, Dong S T, Wang K J, Zhang J W, Liu P. Effect of shading on grain quality at different stages from flowering to maturity in maize. Acta Agron Sin, 2007, 33: 1960–1967 (in Chinese with English abstract) [26]任国玉, 郭军, 徐铭志, 初子莹, 张莉, 邹旭恺, 李庆祥, 刘小宁. 近50年中国地面气候变化基本特征. 气象学报, 2005, 63: 942–956 Ren G Y, Guo J, Xu M Z, Chu Z Y, Zhang L, Zou X K, Li Q Y, Liu X N. Climate changes of Chinese mainland over the past half century. Acta Meteorol Sin, 2005, 63: 942–956 (in Chinese with English abstract) [27]杨彦武, 于强, 王靖. 近40年华北及华东局部主要气候资源要素的时空变异性. 资源科学, 2004, 26(4): 45–50 Yang Y W, Yu Q, Wang J. Spatio-temporal variations of principal climatic factors in north china and part of east China within past 40 years. Resour Sci, 2004, 26(4): 45–50 (in Chinese with English abstract) [28]崔海岩, 靳立斌, 李波, 张吉旺, 赵斌, 董树亭, 刘鹏. 遮阴对夏玉米茎秆形态结构和倒伏的影响. 中国农业科学, 2012, 45: 3497–3505 Cui H Y, Jin L B, Li B, Zhang J W, Zhao B, Dong S T, Liu P. Effects of shading on stalks morphology, structure and lodging of summer maize in field. Sci Agric Sin, 2012, 45: 3497–3505 (in Chinese with English abstract) [29]张祖建, 朱庆森, 王志琴. 水稻胚乳细胞计数方法研究. 江苏农学院学报, 1996, 17(6): 7–11 Zhang Z J, Zhu Q S, Wang Z Q. A method of counting endosperm cells in rice grain. Jiangsu Agric Res, 1996, 17(6): 7–11 (in Chinese with English abstract) [30]何照范. 粮油籽粒品质及其分析技术. 北京: 农业出版社, 1985. pp 329–331 He Z F. Oil Seeds Quality and Analysis Techniques. Beijing: China Agriculture Press, 1985. pp 329–331 (in Chinese with English abstract) [31]Cui H Y, James J C, Jin L B, Zhang J W. Effects of shading on spike differentiation and grain yield formation of summer maize in the field. Int J Biometeorol, 2015, 59: 1189–1200 [32]宋凤斌, 童淑媛. 不同株型玉米的干物质积累、分配及转运特征. 江苏农业学报, 2010, 26: 700–705 Song F B, Tong S Y. Characteristics of dry matter accumulation, distribution and translocation in maize with different plant types. Jiangsu J Agric Sci, 2010, 26: 700–705 (in Chinese with English abstract) [33]戴明宏, 陶洪斌, 王利纳, 王璞. 不同氮肥管理对春玉米干物质生产、分配及转运的影响. 华北农学报, 2008, 23(1): 154–157 Dai M H, Tao H B, Wang L N, Wang P. Effects of different nitrogen managements on dry matter accumulation, partition and transportation of spring maize (Zea mays L.). Acta Agric Boreali-Sin, 2008, 23(1): 154–157 (in Chinese with English abstract) [34]刘伟, 张吉旺, 吕鹏, 杨今胜, 刘鹏, 董树亭, 李登海, 孙庆泉. 种植密度对高产夏玉米登海661产量及干物质积累与分配的影响. 作物学报, 2011, 37: 1301–1307 Liu W, Zhang J W, Lu P, Yang J S, Liu P, Dong S T, Li D H, Sun Q Q. Effect of plant density on grain yield dry matter accumulation and partitioning in summer maize cultivar Denghai 661. Acta Agron Sin, 2011, 37: 1301–1307 (in Chinese with English abstract) [35]孙小玲, 许岳飞, 马鲁沂, 周禾. 植株叶片的光合色素构成对遮阴的响应. 植物生态学报, 2010, 34: 989–999 Sun X L, Xu Y F, Ma L Y, Zhou H. A review of acclimation of photosynthetic pigment composition in plant leaves to shade environment. Chin J Plant Ecol, 2010, 34: 989–999 (in Chinese with English abstract) [36]李潮海, 栾丽敏, 尹飞, 王群, 赵亚丽. 弱光胁迫对不同基因型玉米生长发育和产量的影响. 生态学报, 2005, 25: 824–830 Li C H, Luan L M, Wang Q, Li N, Zhao Y L. Effects of seedling shading and light intensity transfer on photosynthetic efficiency of different maize hybrids. Acta Ecol Sin, 2005, 31: 381–385 (in Chinese with English abstract) [37]崔海岩, 靳立斌, 李波, 董树亭, 刘鹏, 赵斌, 张吉旺. 遮阴对夏玉米干物质积累及养分吸收的影响. 应用生态学报, 2013, 24: 3099–3105 Cui H Y, Jin L B, Li B, Dong S T, Liu P, Zhao B, Zhang J W. Effects of shading on dry matter accumulation and nutrient absorption of summer maize. Chin J Appl Ecol, 2013, 24: 3099–3105 (in Chinese with English abstract) [38]贾士芳, 董树亭, 王空军, 张吉旺, 刘鹏. 弱光胁迫影响夏玉米光合效率的生理机制初探. 植物生态学报, 2010, 34: 1439–1447 Jia S F, Dong S T, Wang K J, Zhang J W, Liu P. Physiological mechanism of shading stress on photosynthetic efficiency in summer maize (Zea mays L.). Chin J Plant Ecol, 2010, 34: 1439–1447 (in Chinese with English abstract) [39]史建国, 崔海岩, 赵斌, 董树亭, 刘鹏, 张吉旺. 花粒期光照对夏玉米产量和籽粒灌浆特性的影响. 中国农业科学, 2013, 46: 4427–4434 Shi J G, Cui H Y, Zhao B, Dong S T, Liu P, Zhang J W. Effect of light on yield and characteristics of grain-filling of summer maize from flowering to maturity. Sci Agric Sin, 2013, 46: 4427–4434 (in Chinese with English abstract) [40]Ren B Z, Zhang J W, Dong S T, Liu P, Zhao B. Effects of duration of water logging at different growth stages on grain growth of summer maize (Zea mays L.) under field conditions. J Agron Crop Sci, 2016, 202: 564–575
[1] YAN Jia-Qian, GU Yi-Biao, XUE Zhang-Yi, ZHOU Tian-Yang, GE Qian-Qian, ZHANG Hao, LIU Li-Jun, WANG Zhi-Qin, GU Jun-Fei, YANG Jian-Chang, ZHOU Zhen-Ling, XU Da-Yong. Different responses of rice cultivars to salt stress and the underlying mechanisms [J]. Acta Agronomica Sinica, 2022, 48(6): 1463-1475.
[2] CHEN Jing, REN Bai-Zhao, ZHAO Bin, LIU Peng, ZHANG Ji-Wang. Regulation of leaf-spraying glycine betaine on yield formation and antioxidation of summer maize sowed in different dates [J]. Acta Agronomica Sinica, 2022, 48(6): 1502-1515.
[3] XU Tian-Jun, ZHANG Yong, ZHAO Jiu-Ran, WANG Rong-Huan, LYU Tian-Fang, LIU Yue-E, CAI Wan-Tao, LIU Hong-Wei, CHEN Chuan-Yong, WANG Yuan-Dong. Canopy structure, photosynthesis, grain filling, and dehydration characteristics of maize varieties suitable for grain mechanical harvesting [J]. Acta Agronomica Sinica, 2022, 48(6): 1526-1536.
[4] KE Jian, CHEN Ting-Ting, WU Zhou, ZHU Tie-Zhong, SUN Jie, HE Hai-Bing, YOU Cui-Cui, ZHU De-Quan, WU Li-Quan. Suitable varieties and high-yielding population characteristics of late season rice in the northern margin area of double-cropping rice along the Yangtze River [J]. Acta Agronomica Sinica, 2022, 48(4): 1005-1016.
[5] LIU Yun-Jing, ZHENG Fei-Na, ZHANG Xiu, CHU Jin-Peng, YU Hai-Tao, DAI Xing-Long, HE Ming-Rong. Effects of wide range sowing on grain yield, quality, and nitrogen use of strong gluten wheat [J]. Acta Agronomica Sinica, 2022, 48(3): 716-725.
[6] YANG Jin, BAI Ai-Ning, BAI Xue, CHEN Juan, GUO Lin, LIU Chun-Ming. Phenotypic and genetic analyses of a rice mutant eed1 with defected embryo and endosperm development [J]. Acta Agronomica Sinica, 2022, 48(2): 292-303.
[7] XIE Cheng-Hui, MA Hai-Zhao, XU Hong-Wei, XU Xi-Yang, RUAN Guo-Bing, GUO Zheng-Yan, NING Yong-Pei, FENG Yong-Zhong, YANG Gai-He, REN Guang-Xin. Effects of nitrogen rate on growth, grain yield, and nitrogen utilization of multiple cropping proso millet after spring-wheat in Irrigation Area of Ningxia [J]. Acta Agronomica Sinica, 2022, 48(2): 463-477.
[8] ZHANG Qian, HAN Ben-Gao, ZHANG Bo, SHENG Kai, LI Lan-Tao, WANG Yi-Lun. Reduced application and different combined applications of loss-control urea on summer maize yield and fertilizer efficiency improvement [J]. Acta Agronomica Sinica, 2022, 48(1): 180-192.
[9] ZHANG Zhi-Xing, CHEN Hua, MIN Xiu-Mei, XU Hai-Long, SONG Guo, LIN Wen-Xiong. Preliminary study of the peptide aptamer R18 promotes grain filling of rice inferior spikelets [J]. Acta Agronomica Sinica, 2021, 47(7): 1332-1341.
[10] LI Jing, WANG Hong-Zhang, LIU Peng, ZHANG Ji-Wang, ZHAO Bin, REN Bai-Zhao. Differences in photosynthetic performance of leaves at post-flowering stage in different cultivation modes of summer maize (Zea mays L.) [J]. Acta Agronomica Sinica, 2021, 47(7): 1351-1359.
[11] KE Jian, CHEN Ting-Ting, XU Hao-Cong, ZHU Tie-Zhong, WU Han, HE Hai-Bing, YOU Cui-Cui, ZHU De-Quan, WU Li-Quan. Effects of different application methods of controlled-release nitrogen fertilizer on grain yield and nitrogen utilization of indica-japonica hybrid rice in pot-seedling mechanically transplanted [J]. Acta Agronomica Sinica, 2021, 47(7): 1372-1382.
[12] LIU Qiu-Yuan, ZHOU Lei, TIAN Jin-Yu, CHENG Shuang, TAO Yu, XING Zhi-Peng, LIU Guo-Dong, WEI Hai-Yan, ZHANG Hong-Cheng. Relationships among grain yield, rice quality and nitrogen uptake of inbred middle-ripe japonica rice in the middle and lower reaches of Yangtze River [J]. Acta Agronomica Sinica, 2021, 47(5): 904-914.
[13] ZHENG Ying-Xia, CHEN Du, WEI Peng-Cheng, LU Ping, YANG Jin-Yue, LUO Shang-Ke, YE Kai-Mei, SONG Bi. Effects of planting density on lodging resistance and grain yield of spring maize stalks in Guizhou province [J]. Acta Agronomica Sinica, 2021, 47(4): 738-751.
[14] ZHU Ya-Li, WANG Chen-Guang, YANG Mei, ZHENG Xue-Hui, ZHAO Cheng-Feng, ZHANG Ren-He. Response of grain filling and dehydration characteristics of kernels located in different ear positions in the different maturity maize hybrids to plant density [J]. Acta Agronomica Sinica, 2021, 47(3): 507-519.
[15] XU Tian-Jun, LYU Tian-Fang, ZHAO Jiu-Ran, WANG Rong-Huan, ZHANG Yong, CAI Wan-Tao, LIU Yue-E, LIU Xiu-Zhi, CHEN Chuan-Yong, XING Jin-Feng, WANG Yuan-Dong, LIU Chun-Ge. Grain filling characteristics of summer maize varieties under different sowing dates in the Huang-Huai-Hai region [J]. Acta Agronomica Sinica, 2021, 47(3): 566-574.
Viewed
Full text


Abstract

Cited

  Shared   
  Discussed   
No Suggested Reading articles found!