土壤水分对玉米光和参数的影响研究

Effects of Soil Moisture on Light and Parameters of Maize

摘要: 东北地区是中国主要的春玉米生产基地之一，其产量水平对中国粮食生产具有十分重要的作用。近年来，我国东北地区的温度不断增加，呈直线上升趋势，平均每十年升高0.4，已经严重地影响了玉米地生长和生产。为了进一步研究土壤水分对玉米主要光合参数的影响，本文于2016年5月至9月在辽宁省锦州市农业气象试验站采取持续无补水方式对东北地区春玉米(“丹玉39”)拔节至抽雄期进行干旱胁迫处理，对该过程中净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)等光合变量进行记录和分析，结果表明：1) 干旱胁迫会导致浅层土壤湿度的干旱程度大于深层土壤湿度。在拔节–抽雄期控水27天可使84% < 土壤湿度 ≤ 55% (轻度–无旱)。2) 任意光照强度下，P_n、T_r、G_s都会随着干旱程度的加重而减小，且在重度干旱胁迫(30% < R ≤ 40%)下达到最低值，PAR = 1200 μmol/m²/s时三个参数的最低值分别约为14.90 μmol/m²/s、0.35 mmol/m²/s、0.026 mmol/m²/s。3) 当PAR ≤ 1000 μmol/m²/s，不同干旱程度、不同干旱持续时间条件下，拔节期P_n、T_r、G_s都表现为随光强增大而增大，随后当光强超过某一值后略有减小，然后逐渐回升，发生光抑制的临界点范围为1000 ≤ PAR≤ 1200 μmol/m²/s。4) 影响玉米叶片生长发育的因素不仅有干旱强度、干旱持续时长，还包括干旱胁迫的时间，深层土壤干旱对光合参数的影响大于浅层土壤。植株的衰老也会导致玉米P_n、T_r、G_s光响应曲线下降，非弱光条件下(PAR > 200 μmol/m²/s)各光合参数的光响应曲线表现为拔节期 > 抽雄期 > 熟乳期。5) 在相同干旱程度下，抽雄期对各光合指标影响最大，为确保玉米产量，应保证此时段内有一定的水分供应。

Abstract: In order to further study the effect of soil moisture on the main photosynthetic parameters of maize, this study conducted drought stress treatment from jointing stage to tasseling stage of spring maize (“Danyu 39”) in Northeast China by continuous no water supplement at Jinzhou Agricultural Meteorological Experimental Station, Liaoning Province, from May to September 2016. The photosynthetic variables such as net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r) were recorded and analyzed. The results showed that: 1) Drought stress can lead to shallow soil moisture more drought than deep soil moisture. Water control at jointing-tasseling stage for 27 days could make 84 % < soil moisture ≤ 55 % (mild drought-no drought). 2) Under any light intensity, P_n, T_r and G_s decreased with the aggravation of drought, and reached the lowest value under severe drought stress (30% < R ≤ 40 %). When PAR = 1200 μmol/m²/s, the lowest values were about 14.90 μmol/m²/s, 0.35 mmol/m²/s and 0.026 mmol/m²/s, respectively. 3) When PAR ≤ 1000 μmol/m²/s, different drought levels and different drought durations, Pn, Tr and Gs increased with the increase of light intensity at jointing stage, and then decreased slightly when the light intensity exceeded a certain value, and then increased gradually. The critical point of photoinhibition was 1000 ≤ PAR ≤ 1200 μmol/m²/s. 4) The factors affecting the growth and development of maize leaves include not only drought intensity, drought duration, but also drought stress time. The effect of drought in deep soil on photosynthetic parameters is greater than that in shallow soil. Plant senescence also led to the decline of P_n, T_r and G_s light response curves of maize. The light response curves of photosynthetic parameters under non-weak light conditions (PAR > 200 μmol/m²/s) showed that jointing stage > tasseling stage > milking stage. 5) Under the same drought degree, the tasseling stage had the greatest impact on each photosynthetic index. In order to ensure the yield of maize, a certain amount of water supply should be ensured during this period.