控墒补灌对新疆春玉米产量和穗叶光合特性的影响

为探讨北疆绿洲区滴灌春玉米的高产栽培水分管理模式,以‘郑单958’(ZD958)和‘垦玉2号’(KY02)为试验材料,研究了控墒补灌对滴灌春玉米大喇叭口期(V12)至蜡熟期(R5)叶片SPAD值以及灌浆期(R3)穗叶色素、光合和荧光等参数的影响.结果表明: 土壤墒度过低或过高均会显著(P<0.05)降低V12-R3期叶片SPAD值,R5期宜保持在田间持水量的65%以上.灌浆期土壤墒度<75%时玉米叶绿素a、b及叶绿素总含量、类胡萝卜素、叶绿素a/b显著下降,但土壤墒度>85%时差异并不显著;土壤墒度<75%时玉米净光合速率(P_n)、蒸腾速率(T_r)及气孔导度(g_s)显著下降,胞间CO₂浓度(C_i)显著上升,但土壤墒度>85%时并未观察到g_s的降低.土壤墒度过高或过低均可显著降低最大光化学效率(F_v/F_m)、潜在活性(F_v/F_o)、PSⅡ实际光化学效率(Φ_PSⅡ)、光化学淬灭(q_P)和光合电子传递速率(rETR)等荧光参数,热耗散量子比率(F_o/F_m)、非光化学淬灭(NPQ)显著升高;通径分析发现,P_n降低主要由F_v/F_o和rETR的下降导致,最终表现为产量的降低.这表明各生育时期土壤墒度保持在V6>60%、V12 >70%、R1 >75%、R3 >80%、R5 >65%是本地区滴灌春玉米获得高产的最佳水分管理模式.

Effects of water-controlled irrigation on maize yield and photosynthetic characteristics of ear leaf in Xinjiang Province,China.

In order to explore the suitable water management patterns for high yield of spring maize under drip irrigation in oasis regions of North Xinjiang, two maize cultivars (Zhengdan 958 and Kenyu 02) were used to study the effect of water-controlled irrigation on the leaf SPAD value at V12-R5 stage, and chlorophyll content, photosyntheticcharacteristics and chlorophyll fluorescence parameters of ear leaf at filling stage in the field. Results showed that the leaf SPAD values peaked under moderate soil moisture treatments during V12-R3 stage. The field capacity of soil moisture above 65% was suitable for the development of corn at R5 stage. The chlorophyll a, b and total chlorophyll contents, carotene, chlorophyll a/b were significantly decreased when soil moisture was less than 75%, however the above parameters had no significant difference when soil moisture was more than 85%. The net photosynthetic rate (P_n), transpiration rate (T_r) and stomata conductance (g_s) of ear leaf were significantly decreased in filling stages when soil moisture was less than 75%, but the intercellular CO₂ concentration (C_i) was significantly increased. The reduction of g_s was not observed when the soil moisture was more than 85% of field capacities. Meanwhile, the variable fluorescence to maximal fluorescence (F_v/F_m), potential activities of PSII (F_v/F_o), PSⅡ actual photochemical efficiency (Φ_PSⅡ), photochemical quenching (q_P) and electron transport rate (rETR) decreased significantly under both higher and lower soil moisture treatments. However, the F_o/F_m and non-photochemical quenching (NPQ) significantly increased at the same time. The path analysis showed that the decrease of P_n resulted from the decrease of F_v/F_o and rETR, which finally resulted in decreased production of spring maize. Therefore, the optimal field moistures for these two spring maize cultivars were >60%, >70%, >75%, >80% and >65% for the growing stages V6, V12, R1, R3 and R5, respectively, to obtain a high yield in the oasis region.