药隔期倒春寒对小麦颖果发育的影响

Effect of Late Spring Coldness during the Anther Differentiation Period on the Caryopsis Development of Wheat

以抗倒春寒性弱的小麦品种新麦26(XM26)和抗倒春寒性强的烟农19(YN19)为试验材料,进行大田盆栽试验。于小麦幼穗分化的药隔形成期在智能超低温光照培养箱内进行低温(2℃和-2℃)胁迫处理,以10℃作为对照组(CK)。于花后每隔7d进行取样,对小麦强势和弱势颖果的长度、宽度和厚度进行观测分析,同时采用石蜡切片技术观察果皮、胚乳细胞及大、小淀粉粒的显微结构,以探明药隔期倒春寒胁迫下小麦颖果发育的显微结构特征。结果表明:(1)药隔期倒春寒会降低小麦颖果的长度、宽度和厚度,且降幅随倒春寒胁迫程度的加强(2℃→-2℃)而增大,成熟期小麦颖果长度、宽度和厚度分别减小1.17%~4.41%、1.57%~10.22%和1.42%~9.40%,倒春寒胁迫下成熟期两品种小麦各处理弱势粒颖果长/宽、长/厚、宽/厚比值均高于强势粒颖果。(2)药隔期倒春寒会减缓早期颖果果皮降解速率,同时还会抑制两品种小麦颖果胚乳细胞淀粉粒的发育。(3)药隔期倒春寒降低小麦强、弱势颖果胚乳细胞内大、小淀粉粒的周长和面积,花后28d强势粒颖果胚乳细胞内大、小淀粉粒周长和面积分别下降8.17%~14.66%和14.08%~17.98%、0.94%~5.00%和2.59%~10.03%,弱势粒颖果分别下降3.08%~10.31%和6.56%~8.70%、3.17%~6.39%和11.85%~16.17%,且强势粒颖果内大淀粉粒周长和面积下降较多,而弱势粒颖果内小淀粉粒周长和面积下降较多。综上所述,药隔期倒春寒通过减缓小麦颖果发育早期果皮降解,抑制胚乳细胞淀粉粒的发育,降低胚乳细胞内大、小淀粉粒的周长和面积,从而降低小麦颖果的长度、宽度和厚度,导致小麦籽粒库容降低,最终降低小麦粒重。

A field pot experiment was conducted using Xinmai26(XM26)with weak resistance to late spring coldness and Yannong19(YN19)with strong resistance to late spring coldness.Low temperature(2℃and-2℃)stress treatment was carried out in intelligent ultra-low temperature light incubator during the anther differentiation period of young wheat spike differentiation,and 10℃was used as CK control group.The length,width and thickness of the superior and inferior caryopsis of wheat were analyzed by sampling every 7 days after anthesis.At the same time,the microstructures of pericarp,endosperm cells and large and small starch grains were observed by paraffin sectioning technique,so as to explore the microstructures of caryopsis development in wheat under the late spring coldness during the anther differentiation period.The results showed as follows:(1)the length,width and thickness of wheat caryopsis decreased with the increase of cold stress(2℃→-2℃).The length,width and thickness of wheat caryopsis decreased by 1.17%-4.41%,1.57%-10.22%and 1.42%-9.40%,respectively,at the mature stage.The ratios of length/width,length/thickness and width/thickness of inferior grain caryopsis were higher than that of superior grain caryopsis in all treatments at maturity stage.(2)The degradation rate of early caryopsis pericarp was slowed down.Meanwhile,the development of starch granules in caryopsis endosperm cells of two wheat cultivars was inhibited.(3)The circumference and area of large and small starch grains in wheat superior and inferior caryopsis were decreased by 8.17%-14.66%,14.08%-17.98%,0.94%-5.00%and 2.59%-10.03%in endosperm cells of dominant caryopsis at 28 days after anthems.The circumference and area of large and small starch grains decreased by 3.08%-10.31%,6.59%-8.70%,3.17%-6.39%and 11.85%-16.17%in endosperm cells of inferior grain caryopsis.The circumference and area of large starch grains decreased more in dominant grain caryopsis,while the circumference and area of small and medium starch grains decreased more in inferior grain caryopsis.In conclusion,late spring coldness during the anther differentiation period can slow down the degradation of pericarp cells of early wheat caryopsis development,inhibit the development of starch grains in endosperm cells,reduce the circumference and area of large and small starch grains in endosperm cells,and thus reduce the length,width and thickness of wheat caryopsis,resulting in the decrease of grain storage capacity of wheat,and ultimately reduce wheat grain weight.