药隔期低温胁迫对小麦功能叶超微结构及光合特性的影响

Effects of Low Temperature Stress during the Anther Differentiation Period on Leaf Anatomical Structure and Photosynthetic Characteristics of Wheat

以抗倒春寒能力不同的两个小麦品种烟农19 (YN19)和新麦26 (XM26)为供试材料,于小麦幼穗分化的药隔期利用超低温人工气候培养箱进行4℃和-4℃两个温度处理,以低温处理期间大田环境平均温度10℃为对照(CK),观测不同程度低温处理下小麦功能叶超微结构及光合特性的变化。结果表明:(1)药隔期低温胁迫显著增加供试两品种小麦功能叶SOD、POD、CAT酶活性和MDA含量,其中CAT酶活性增幅最大,XM26在4℃、-4℃处理下功能叶CAT活性较CK分别增加了48.68%和87.55%,YN19则分别增加了76.59%和110.39%,总体来看YN19的抗氧化酶活性增幅均大于XM26,具有较强的活性氧清除能力。(2)低温胁迫破坏小麦功能叶叶绿体结构。XM26在4℃、-4℃处理功能叶叶绿体数和叶绿体面积较CK分别下降12.43%、24.97%和57.68%、5.88%,YN19分别下降14.56%、16.69%和25.88%、61.90%。随着温度的降低(4℃→-4℃),供试两品种小麦叶片的基粒片层数量和厚度大幅下降,细胞膜受到不同程度的损伤,基粒片层开始解体。(3)随着低温胁迫程度加深,供试两品种小麦叶绿素a(Chla)、叶绿素b(Chlb)和Chla+Chlb含量下降,XM26在-4℃低温胁迫下较CK分别降低26.97%、27.39%、31.78%,YN19则分别降低34.36%、23.81%、26.91%,表明低温胁迫使叶片内部结构破坏,导致叶绿素含量下降。(4)与CK相比,低温胁迫下小麦功能叶片净光合速率(Pn)随着低温胁迫程度加深呈降低趋势,胞间CO_(2)浓度(Ci)呈逐升趋势,XM26在4℃和-4℃低温胁迫当天其Pn分别下降31.84%、92.04%,YN19则分别下降17.42%、89.62%,表明小麦叶片Pn下降主要是由非气孔限制因素导致。因此,药隔期低温胁迫会使小麦叶片功能受损,导致其光合能力下降,大田生产中可选用抗倒春寒能力强的品种,加强栽培技术管理,提高小麦抗寒性,减轻倒春寒对小麦造成的危害。

Two wheat varieties differing in spring cold-sensitivity Yannong 19(YN19) and Xinmai 26(XM26) were used as experimental materials. During the anther differentiation period, two temperature treatments of 4℃ and-4℃were set up in the smart climate box. At the same time, the average temperature of the ambient temperature was 10℃as the control(CK). After the treatment, effects of low temperature stress during the anther differentiation period on leaf anatomical structure and photosynthetic characteristics of wheat were observed. The results showed that:(1) low temperature stress during the anther differentiation period significantly increased the SOD, POD, CAT enzyme activities and MDA content of functional leaves of the two wheat varieties, and the CAT enzyme activity increased the most. Compared with CK, XM26 increased by 48.68% and 87.55% at 4℃ and-4℃, while YN19 increased by 76.59% and 110.39%, respectively. Overall, the increase in antioxidant enzyme activity of YN19 was greater than that of XM26, and it had a strong ability to eliminate reactive oxygen species.(2) Low temperature stress destroys the chloroplast structure of wheat functional leaves. Compared with CK, the chloroplast number and chloroplast area of XM264℃ and-4℃ decreased by 12.43%, 24.97% and 57.68%, 5.88%, respectively, and YN19 decreased by 14.56%, 16.69% and 25.88%, 61.90%, respectively. With the decrease of temperature(4℃→-4℃), the number and thickness of grana lamellae in the leaves of the two tested wheat varieties also decreased significantly, the cell membrane was damaged to different degrees, and the grana lamella began to disintegrate.(3) With the deepening of low temperature stress, the contents of chlorophyll a(Chla), chlorophyll b(Chlb) and Chla+Chlb of the two tested wheat varieties decreased, and XM26 decreased by 26.97%, 27.39%, 31.78% compared with CK under-4℃ low temperature stress, while YN19 decreased by 34.36%, 23.81%, and 26.91%, respectively, indicating that low temperature stress destroyed the internal structure of leaves and reduces chlorophyll content.(4) Compared with CK,the net photosynthetic rate(Pn) of functional leaves of wheat under low temperature stress decreased gradually, and the intercellular CO2concentration(Ci) increased gradually. The Pn of XM26 decreased by 31.84% and 92.04%,while that of YN19 decreased by 17.42% and 89.62% on the day of low temperature stress at 4℃ and-4℃,respectively, indicating that the decrease of Pn in wheat leaves was mainly caused by non-stomatal limiting factors.To sum up, the low temperature stress during the anther differentiation period will damage the wheat leaf function and reduce its photosynthetic capacity. Therefore, the cultivation and management measures should be strengthened in field production to improve the cold resistance of wheat and reduce the damage caused by late spring cold to wheat.