引用本文
周卫霞, 王秀萍, 穆心愿, 李潮海. 弱光胁迫对不同基因型玉米雌雄花发育和授粉结实能力的影响. 作物学报, 2013, 39(11): 2065-2073[ZHOU Wei-Xia, WANG Xiu-Ping, MU Xin-Yuan, LI Chao-Hai. Effects of Low-light Stress on Male and Female Flower Development and Pollination and Fructification Ability of Different Maize (Zea mays L.) Genotypes . 作物学报, 2013, 39(11): 2065-2073]  
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作物学报编辑部
弱光胁迫对不同基因型玉米雌雄花发育和授粉结实能力的影响
周卫霞1, 王秀萍2, 穆心愿1, 李潮海1,*
1河南省粮食作物高产高效协同创新中心 / 河南农业大学农学院, 河南郑州 450002
2河南省气象科学研究所, 河南郑州 450003
*通讯作者(Corresponding author): 李潮海, E-mail:lichaohai2005@163.com, Tel: 0371-63555629
收稿日期:2013-06-24
基金:本研究由国家现代农业产业技术体系建设专项(CARS-2-19)资助。
摘要

以不耐阴型玉米豫玉22和耐阴型玉米郑单958为试验材料, 设置自然光照和弱光胁迫2个处理, 研究弱光胁迫对不同基因型玉米雌雄花发育的影响。研究结果表明, 弱光胁迫延缓了雌雄穗的生长发育, 表现为抽雄、吐丝和盛花期延迟, 花期和雌雄间隔期延长。弱光胁迫下, 在吐丝期不耐阴型玉米花粉量比对照显著增加, 耐阴型玉米花粉量与对照差异较小; 不耐阴型玉米花粉表面网纹在弱光胁迫下变粗且间隙增大, 花粉萌发孔及其附近严重畸形, 有的明显内陷, 花粉内淀粉粒数目显著减少, 营养供应能力减弱, 耐阴型玉米在弱光胁迫下花粉表面网纹略有加粗或没有变化, 萌发孔略微凹陷且程度远低于不耐阴型玉米, 花粉中淀粉粒密度略有降低。遮光处理后, 不耐阴型玉米的花粉活力、花粉萌发率和萌发速率表现为下降, 而耐阴型玉米表现为上升。花2个基因型玉米穗长和穗粒数减少, 不耐阴型玉米受弱光胁迫影响的程度高于耐阴型玉米。雌雄间隔期延长、营养供应能力减弱导致的花粉畸形、花丝生长速率和可授粉花丝数目的减少以及籽粒IAA含量的下降和ABA含量的增加是弱光条件下玉米穗粒数显著减少的主要原因。

关键词: 玉米; 弱光胁迫; 光恢复; 基因型; 穗粒数
Effects of Low-light Stress on Male and Female Flower Development and Pollination and Fructification Ability of Different Maize (Zea mays L.) Genotypes
ZHOU Wei-Xia1, WANG Xiu-Ping2, MU Xin-Yuan1, LI Chao-Hai1,*
1 Collaborative Innovation Center for High Yield and High Efficiency Production of Cereal Crop in Henan Province / Agronomy College of Henan Agricultural University, Zhengzhou 450002, China
2 Henan Institute of Meteorological Sciences, Zhengzhou 450003, China
Abstract

A split plot experiment was conducted under field conditions to study the effects of low-light stress on the ear and tassel development, pollination and seed-setting rate using two maize (Zea mays L.) hybrids (low light sensitive hybrid Yuyu 22 and low light tolerant hybrid Zhengdan 958). Low-light stress from three days before tasselling to ten days after silking was obtained using 50% transmittance shading nets. The results showed that low-light stress caused a slowdown of ear and tassel growth and development rate, delayed the tasselling date, silking date and full flowering date, prolonged the anthesis-silking interval (ASI). Daily pollen quantity was higher under low-light stress than that of the control at silking with a larger difference compared with the low light sensitive hybrid. For the low light sensitive hybrid under low light stress, reticula and gaps in the surface of pollen were increased, pollen aperture and its near part were severely deformed with significantly retraction, nutrient supply was reduced due to the reduction of starch grains in the pollen. While for the low light tolerant hybrid under low light stress, pollen surface characters were similar to that of control, with a little retraction of the pollen aperture and decrease of starch grain density in the pollen. Under low light stress, pollen activity, pollen emergence rate and pollen tube growth rate of the low light sensitive hybrid decreased while that of the low light tolerant hybrid increased. Silk elongation rate and number of silks emerged from the husks were decreased and decreased more in the ear tip than in the ear base. Ear length and kernel number per ear decreased in both hybrids and decreased more in low light sensitive hybrid. Prolonged ASI, deformed pollen, reduction of nutrient supply in pollen, decreased silk elongation rate and number of silks emerged from the husks, and the decrease of kernel IAA content and the increase of kernel ABA content were the primary causes leading to the reduction of ear kernel number.

Keyword: Maize; Low-light stress; Light recovery; Genotype; Kernel number
引言

近年来, 我国玉米种植面积和产量逐年增加, 但仍面临玉米供应不足的挑战[1]。黄淮海地区是我国夏玉米主产区, 在玉米生长发育进程中常遭遇阴雨天气。花期阴雨严重影响玉米授粉结实的能力, 降低玉米的稳产性, 影响粮食安全。国内外研究发现, 玉米对弱光胁迫的响应存在品种、生育阶段、持续时间和遮光程度的显著差异[2,3,4,5,6]。弱光胁迫下, 玉米光合细胞中叶绿体结构畸形[7]、光合作用能力下降[8,9]、干物质积累减少[5], 产量降低且品质改变[10,11]。研究表明, 弱光胁迫下玉米雌雄间隔期延长导致花期不遇[12,13], 花丝数目和雄穗分枝数下降[5,14], 花粉营养供给不足、呼吸作用加强、同化物运输受阻, 导致颖花退化、雄花育性降低, 影响受精结实[15], 穗行数和穗粒数减少[16,17,18]。尽管前人就弱光胁迫对玉米雌雄穗发育进行过大量研究, 但对不同耐阴型玉米在弱光胁迫下授粉能力及其机制的研究鲜见报道。本文从花丝和花粉生长发育的角度探讨玉米响应弱光胁迫的基因型差异, 旨在探明黄淮海地区花期阴雨造成玉米穗粒数下降的主要原因, 充实玉米弱光胁迫研究的理论知识, 为玉米抗逆育种和栽培提供参考。

1 材料与方法
1.1 试验处理与设计

2011—2012年在河南农业大学郑州科教园区网室。盆栽种植, 塑料盆高30 cm, 内径38 cm。土壤经风干后过1 cm×1 cm方孔土筛, 每盆装土15 kg。供试土壤为潮土, 含有机质8.24 g kg-1、水解氮 63.5 mg kg-1、速效磷21.5 mg kg-1、速效钾133.3 mg kg-1。播种前每盆施复合肥(N 25%, P2O518%、K2O 12%) 12 g作基肥, 大喇叭口期追施5 g尿素。播种前浇透水, 其他管理同一般大田。

试验采用二因素裂区设计, 主因素为光照, 设置自然光照(CK, L)和遮光(50% CK, S) 2个处理, 副因素为品种, 为不耐阴型玉米豫玉22 (YY22)和耐阴型玉米郑单958 (ZD958)[12]。在遮阴棚和网室东西两侧使用透光率为50%的黑色遮阳网进行弱光胁迫处理(遮阴棚为弧顶钢架结构, 高5 m, 东西方向设置), 保证田间小气候和光质与自然阴天的一致性[3]。于抽雄前3 d遮光处理, 吐丝后10 d恢复自然光照。按各品种所需适宜密度摆放试验盆, 豫玉22为40 500株 hm-2, 郑单958为67 500株 hm-2。

1.2 测定项目与方法

1.2.1雌雄间隔期和雌雄花期 记录玉米开花期(约60%玉米抽雄散粉)和吐丝期(约60%玉米花丝伸出苞叶2 cm以上)以及二者的终止时间, 记录花粉量最大的时期(盛花期)。

1.2.2花粉取样 在吐丝期(雌雄相遇时)上午10:00左右取样, 带回实验室测定, 每个处理取3穗。

1.2.3花粉量 将雄穗完全置一大纸袋中, 小幅抖动至无花粉落下, 去除杂质后称取花粉重量。

1.2.4花粉活力 取称重后的花粉, 用氯化三苯基四氮唑(TTC)染色法测定[19], 外形圆、大且染色较深的花粉粒为有活性的花粉, 空瘪、皱缩和染色浅的花粉为无活性的花粉。

1.2.5花粉萌发率和萌发速率 称取5 mg花粉于直径60 mm的培养皿中, 倒入18 mL培养液(含CaCl2·2H2O 300.0 mg L-1, H3BO3 100.0 mg L-1, 蔗糖222.5 g L-1), 在20~25℃的条件下放置1~2 h后用400×光学显微镜观察[20], 萌发以花粉管长度大于花粉直径为准, 萌发速率=花粉管长度/培养时间。

1.2.6花粉超微结构观察 用0.1 mol L-1磷酸缓冲液洗3次, 2.5%戊二醛固定液预固定2 h, 磷酸缓冲液冲洗多余的戊二醛, 1%锇酸固定2 h, 清洗3次, 30%-40%-50%-70%-80%-90%-100%乙醇梯度脱水, 转入醋酸戊酯15 min, 取出样品放入干燥器中干燥, 真空喷镀, 以日产S-450型扫描电镜观察、照相[21]。

1.2.7可溶性糖含量 采用蒽酮比色法测定[22]。

1.2.8花丝生长速率 选取长势相同的30株玉米套袋, 从弱光处理至吐丝期, 每3 d取样一次, 每次取3~5个果穗。以常规法量取玉米果穗上(顶部3~10周)、中(3~10周)、下(基部往上3~10周)花丝长度, 每穗各部位取4个方向, 每个方向上量取10~15根, 计算花丝生长速率。

1.2.9伸出苞叶的花丝数目 在吐丝期和吐丝后4 d取样, 每次取3~5个果穗, 剪取伸出苞叶的花丝并计数。

1.2.10苞叶和果穗长度 在弱光处理前、吐丝期、吐丝后10 d和20 d用常规法测定果穗及苞叶

长度。

1.2.11籽粒内源激素IAA和ABA含量 在吐丝后10 d和20 d, 取果穗中部籽粒, 用间接酶联免疫法[23]测定IAA和ABA含量, 试剂盒由中国农业大学生物实验室提供。

1.3 数据分析

经分析, 2年试验结果趋势一致, 文中花期和花粉生活力为2011年数据, 花粉量、电镜为2012年数据, 其余数据为2年数据的平均值。用SPSS17.0进行数据显著性检验。用Sigma10.0软件绘制图表, 数据用平均值±标准偏差表示。

2 结果与分析
2.1 弱光胁迫对不同基因型玉米雌雄花期的影响

表1表明, 弱光胁迫延长了玉米雌雄花的生长发育, 表现为抽雄、吐丝和盛花期延迟, 花期和雌雄间隔期延长。弱光胁迫下耐阴型玉米豫玉22抽雄期延长2 d, 吐丝期延长7 d, 耐阴型玉米郑单958仅吐丝期延长3 d; 不耐阴型玉米豫玉22的散粉始期推迟2 d, 耐阴型玉米郑单958不受影响; 豫玉22的散粉持续期延长2 d, 雌雄相遇后仅有3 d的授粉时间, 郑单958散粉持续期延长1 d, 雌雄相遇后有6 d的授粉时间; 豫玉22雌雄间隔期比郑单958延长4 d。

表1 弱光胁迫对不同基因型玉米雌雄花期的影响 Table 1 Response of male and female flowering to low light stress
2.2 弱光胁迫对不同基因型玉米雄花发育的影响

2.2.1 对不同基因型玉米花粉量的影响 由图1可见, 弱光胁迫下不同基因型玉米雄穗花粉量均比对照增加, 不耐阴型玉米豫玉22弱光胁迫下花粉量比对照增加20.82%, 差异达显著水平, 耐阴型玉米郑单958仅比对照增加4.49%且差异不显著。

图1 弱光胁迫对不同基因型玉米花粉量的影响L: 自然光照; S: 遮光处理。不同字母表示差异在0.05水平显著。Fig. 1 Effect of low light stress on pollen weight of two different maize genotypesL: nature light; S: shade. Bars superscripted by different letters are significantly different at the 0.05 probability level.

2.2.2 对不同基因型玉米花粉活力、萌发率和萌发速率的影响 由图2可见, 不同基因型玉米花粉生活力对弱光胁迫的响应不同, 表现为豫玉22花粉活力(图2-A)和花粉萌发率(图2-B)分别比对照降低14.53%和37.04%, 差异均达显著水平; 郑单958分别比对照增加8.16%和9.34%, 差异均不显著; 豫玉22花粉萌发速率(图2-C)比对照降低5.37%, 差异不显著, 郑单958比对照增加23.21%, 差异达显著水平。可见, 不耐阴型玉米豫玉22花粉生活力对弱光胁迫的响应主要表现为花粉活力和萌发率的大幅下降, 耐阴型玉米郑单958表现为萌发速率的大幅提高。

2.2.3 对不同基因型玉米花粉表面超微结构和淀粉含量的影响 图3显示, 豫玉22花粉表面网纹在弱光胁迫下变粗且间隙增大, 花粉萌发孔及其附近严重畸形, 有的明显内陷(图3-B); 郑单958花粉在弱光胁迫下花粉表面网纹略有加粗或没有变化, 萌发孔略微凹陷且程度远低于豫玉22 (图3-D)。豫玉22花粉内淀粉粒密度明显降低(图3-F); 郑单958花粉内淀粉粒密度略有降低(图3-H)。可见, 弱光胁迫下, 豫玉22花粉结构受到严重损伤且营养供应能力减弱。

图2 弱光胁迫对不同基因型玉米花粉活力、萌发率和萌发速率的影响L: 自然光照; S: 遮光处理。不同字母表示差异在0.05水平显著。Fig. 2 Effects of f low light stress on pollen viability, germination percentage and germination rate of two different maize genotypesL: nature light; S: shade. Bars superscribed by different letters are significantly different at the 0.05 probability level.

图3 弱光胁迫对不同基因型玉米花粉表面超微结构和淀粉含量的影响A、B、C和D分别表示豫玉22自然光照、豫玉22遮光处理、郑单958自然光照和郑单958遮光处理的花粉外观扫描结构(×800); E、F、G和H分别表示豫玉22自然光照、豫玉22遮光处理、郑单958自然光照和郑单958遮光处理在透射电镜下的花粉淀粉粒数量, 标尺=5 μm。S为淀粉粒。Fig. 3 Effects of low light stress on super-micro structure of pollen surface and starch grain number of two different maize genotypesA, B, C, and D represent the pollen super-micro structure of pollen surface of Yuyu 22 nature light treatment, Yuyu 22 shade treatment, Zhengdan 958 nature light treatment, and Zhengdan958 shade treatment, respectively, ×800. E, F, G, and H represent the pollen starch grain number of Yuyu 22 nature light treatment, Yuyu 22 shade treatment, Zhengdan 958 nature light treatment, and Zhengdan 958 shade treatment, respectively, bar = 5 μm. S: starch grain.

2.3 弱光胁迫对不同基因型玉米穗位叶可溶性糖含量的影响

由图4可见, 不同基因型玉米在弱光胁迫下穗位叶中可溶性糖含量均下降, 豫玉22比对照减少18.34%, 差异达显著水平, 郑单958比对照减少8.43%, 差异不显著。可见, 弱光胁迫下豫玉22穗位叶可溶性糖的减少幅度远大于郑单958。

2.4 弱光胁迫对不同基因型玉米雌花发育的影响

2.4.1 对花丝生长速率的影响 由表2可见, 弱光胁迫下2个基因型玉米不同部位花丝的生长速率均显著下降, 豫玉22果穗上部、中部和下部花丝生长速率分别降低23.08%、22.84%和17.80%, 郑单958分别降低21.21%、20.35%和16.82%, 可见, 不同基因型玉米花丝生长速率对弱光胁迫的响应较为一致, 但豫玉22受影响的程度略高于郑单958, 果穗上部花丝受到的影响最大, 向下逐渐减弱。

2.4.2 对伸出苞叶花丝数目的影响 由图5可见, 吐丝期2个基因型玉米伸出苞叶的花丝数目在弱光胁迫下均显著减少, 豫玉22和郑单958分别比对照降低58.68%和39.22%; 吐丝后4 d, 豫玉22的伸出苞叶花丝数比对照减少59.90%, 差异达极显著水平, 郑单958仅比对照降低6.47%, 差异不显著。

图4 弱光胁迫对不同基因型玉米叶片可溶性糖含量的影响L: 自然光照; S: 遮光处理。不同字母表示差异在0.05水平显著。Fig. 4 Effects of low light stress on soluble sugar content in ear leaf of two different maize genotypesL: Nature light; S: Shade. Bars superscripted by different letters are significantly different at the 0.05 probability level.

2.5 弱光胁迫对不同基因型玉米苞叶和果穗生长的影响

由表3可见, 弱光胁迫延缓苞叶和果穗的生长。弱光胁迫下豫玉22苞叶长度与对照差异不显著, 郑单958则显著减少; 豫玉22和郑单958的果穗长分别在吐丝期和吐丝后10 d显著减少。恢复自然光照后, 处理间差异减小。吐丝期、吐丝后10 d和20 d, 受弱光胁迫的豫玉22苞叶长度分别比对照减少2.74%、4.76%和8.51%, 穗长分别减少17.02%、41.85%和31.75%; 郑单958苞叶长度分别减少13.65%、12.49%和9.90%, 穗长分别减少4.42%、13.76%和12.31%。由此看出, 不耐阴型玉米豫玉22果穗对弱光更敏感, 耐阴型玉米郑单958则表现为苞叶对弱光更敏感。

表2 弱光胁迫对不同基因型玉米花丝生长速率的影响 Table 2 Effects of low light stress on the growth velocity of filament in two different maize genotypes (cm d-1)
表3 弱光胁迫对不同基因型玉米苞叶和果穗长度的影响 Table 3 Effects of low light stress on the length of bract and ear in two different maize genotypes
2.6 弱光胁迫对不同基因型玉米果穗籽粒IAA和ABA含量的影响

弱光胁迫下, 不耐阴型玉米豫玉22中部籽粒IAA含量显著降低, 耐阴型玉米郑单958显著增加(图6-A), 2个基因型玉米籽粒ABA含量均增加且豫玉22在吐丝后10 d与对照差异达显著水平(图6-B)。吐丝后10 d和20 d, 受弱光胁迫的豫玉22籽粒IAA含量分别比对照降低19.92%和26.88%, ABA含量增加38.62%和9.11%; 郑单958籽粒IAA和ABA分别比对照增加32.94%和21.52%, 18.41%和0.18%。

2.7 弱光胁迫对不同基因型玉米穗粒数的影响

由图6可见, 弱光胁迫下2个基因型玉米穗粒数均显著减少, 豫玉22和郑单958分别比对照减少59.00%和38.45%, 不耐阴型玉米豫玉22的减少幅度远大于耐阴型玉米郑单958。

图5 弱光胁迫对不同基因型玉米伸出苞叶花丝数目的影响YY22L: 豫玉22自然光照; YY22S: 豫玉22遮光处理; ZD958L: 郑单958自然光照; ZD958S: 郑单958遮光处理。S: 吐丝期; DAS4: 吐丝后4 d。不同字母表示差异在0.05水平显著。Fig. 5 Effects of low light stress on the number of filament stick out from bracts of two different maize genotypesYY22L: Yuyu 22 nature light treatment, YY22S: Yuyu 22 shade treatment, ZD958L: Zhengdan 958 nature light treatment, ZD958S: Zhengdan 958 shade treatment. S: silking; DAS4: 4 days after silking. Bars superscripted by different letters are significantly different at the 0.05 probability level.

3 讨论

抽雄开花期是玉米生长发育的关键时期, 此时如遇特殊天气和环境胁迫将严重影响产量[17,24,25,26]。黄淮海地区在7月下旬至8月上中旬常出现阴雨寡照天气, 导致玉米雌雄间隔延长, 造成花期不遇和产量的下降[12,13,27]。弱光胁迫下花器发育减慢[5,14]且营养供应不足, 影响受精结实和籽粒建成[15,25,26], 而授粉成功与否, 直接决定了籽粒建成和产量潜力[25,28]。本文研究结果表明, 弱光胁迫延缓了雌雄花的生长发育, 抽雄、吐丝和盛花期均延迟, 花期和雌雄间隔期延长, 不耐阴型玉米豫玉22生长发育的延缓程度和雌雄间隔期均大于耐阴型玉米郑单958。

图6 弱光胁迫对不同基因型玉米籽粒IAA和ABA含量的影响YY22L: 豫玉22自然光照; YY22S: 豫玉22遮光处理; ZD958L: 郑单958自然光照; ZD958S: 郑单958遮光处理。DAS10: 吐丝期后10 d; DAS20: 吐丝后20 d。不同字母表示差异在0.05水平显著。Fig. 6 Effects of low light stress on kernel IAA and ABA contents in two different maize genotypesYY22L: Yuyu 22 nature light treatment, YY22S: Yuyu 22 shade treatment, ZD958L: Zhengdan 958 nature light treatment, ZD958S: Zhengdan 958 shade treatment. DAS10: 10 days after silking; DAS4: 20 days after silking. Bars superscripted by different letters are significantly different at the 0.05 probability level.

花粉数量减少和生长能力下降均会导致授粉失败进而降低产量[29,30]。本研究发现, 遮光处理后两个基因型玉米的花粉量均高于对照, 表明弱光胁迫下花粉数量对授粉没有影响。花粉活力变化对单株粒重造成显著影响[24], 花粉萌发除与本身的质量有关外, 也与萌发的环境条件密切相关[31]。本研究发现, 遮光处理后, 不耐阴型玉米豫玉22的花粉活力、花粉萌发率和萌发速率均下降, 而耐阴型玉米郑单958均增加。玉米植株在正常生长条件下的花粉形状近乎圆球形, 具有略为粗糙的外壳及小而明亮且稍为突出的萌发孔, 胁迫条件下, 花粉外壳出现逐渐加宽加长的网纹状突起[21]。本研究结果表明不耐阴型玉米豫玉22花粉表面网纹在弱光胁迫下变粗且间隙增大, 花粉萌发孔及其附近严重畸形, 有的明显内陷, 耐阴型玉米郑单958在弱光胁迫下花粉表面网纹略有加粗或没有变化, 萌发孔及其附近略微凹陷, 不耐阴型玉米豫玉22花粉粒中的淀粉粒数目和叶片营养供给能力大幅下降而耐阴型玉米郑单958均略有降低, 显示郑单958花粉粒营养较充足。通过比较可知, 营养不足是导致不耐阴型玉米豫玉22花粉畸形、生活力下降的主要原因, 而花粉营养不足应该是弱光下同化物合成和运输能力下降和呼吸加强等共同造成的[15]。

图7 弱光胁迫对不同基因型玉米穗粒数的影响L: 自然光照; S: 遮光处理。不同字母表示差异在0.05水平显著。Fig. 7 Effects of low light stress on kernel number of two different maize genotypesL: nature light; S: shade. Bars superscripted by different letters are significantly different at the 0.05 probability level.

花丝最早出现在果穗中下部, 顶部出现最晚。光照充足则花丝发育早、数量多, 顶部花丝生长发育正常[32], 有利于受精结实。如果花丝生长发育减慢, 吐丝期延迟则易导致雌雄间隔期延长, 雌雄花期不能相遇, 导致穗粒数、籽粒库容减少和产量下降[33,34]。本研究发现, 不同基因型玉米在弱光胁迫下的花丝生长速率均显著下降, 不耐阴型玉米豫玉22的下降幅度高于耐阴型郑单958, 果穗顶部的下降幅度最大, 其次是中部。由花丝生长速率降低引起的花期不遇和产量的下降会因苞叶过长而加剧[35], 且苞叶过长导致的花丝活力下降比花粉活力本身的下降对经济产量造成更大的影响[24,36]。本文研究结果表明, 不耐阴型玉米豫玉22在弱光胁迫下的苞叶长度与对照差异较小, 而耐阴型玉米郑单958的苞叶长度显著降低, 同时豫玉22果穗长度下降的幅度高于郑单958, 果穗和苞叶对弱光胁迫响应上的差异直接导致花丝抽出苞叶速率的不同, 这是造成豫玉22和郑单958在弱光胁迫后雌雄间隔期变化不同的重要原因, 也是导致二者果穗结实率不同的重要因素。

激素含量变化严重影响籽粒的物质供应和胚乳的正常发育, 进而影响籽粒建成和灌浆结实。研究表明, IAA在籽粒中的积累达到一定的量时可促进粒重的增加[37], 增强淀粉合成相关酶的活性[38], 含量降低易导致籽粒营养物质的缺乏而败育[39]。虽然没有直接证据证明ABA可导致籽粒的败育, 但ABA很可能是籽粒败育的参与者[40,41]。研究表明, 果穗顶部ABA的大量积累会抑制胚乳细胞的分裂, 造成穗粒数减少和限制籽粒灌浆[33], 而较低含量的ABA有利于籽粒灌浆[38,42]。本研究发现, 弱光胁迫下不耐阴型玉米豫玉22籽粒IAA含量显著降低, ABA含量在吐丝后10 d显著增加, 而耐阴型玉米郑单958籽粒IAA显著增加且ABA含量与对照差异不大。表明不耐阴型玉米豫玉22籽粒的生长发育在弱光胁迫下受到严重抑制而郑单958籽粒IAA含量的增加反而对其生长发育起到了较大的促进作用。

4 结论

玉米授粉和结实能力对弱光胁迫的响应存在明显的基因型差异。花器生长发育受损造成的花期不遇和授粉能力的降低、籽粒IAA含量减少和ABA含量的增加是不耐阴型玉米在弱光胁迫下穗粒数减少的主要原因。

The authors have declared that no competing interests exist.

作者已声明无竞争性利益关系。The authors have declared that no competing interests exist.

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