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Title: [Effects of water and fertilizer coupling on photosynthetic characteristics of maize leaves in ear position at filling stage in an apple-maize intercropping system in Losses Plateau of west Shanxi Province, China.].
Author: Gao F, Wang RS, Xu HS, Wang DM, Yang ZR.
Journal: Ying Yong Sheng Tai Xue Bao; 2016 Aug; 27(8):2477-2490. PubMed ID: 29733134.
Abstract:
Taking a typical apple×maize intercropping system in the loess region of Shanxi Pro-vince, China as test object, the current study analyzed the photosynthetic characteristics of maize leaves of ear position at filling stage under different irrigation and fertilization regimes. There were three irrigation levels [low (W₁), 50% field capacity (Fc); medium (W₂), 65% Fc; and high (W₃), 85% Fc], three fertilizer levels {F₁ [N (289 kg·hm^-2) + P₂O₅ (118 kg·hm^-2) + K₂O (118 kg·hm^-2)]; F₂ [N (412.4 kg·hm^-2) + P₂O₅ (168.8 kg·hm^-2) + K₂O (168.8 kg·hm^-2)], F₃ [N (537 kg·hm^-2) + P₂O₅ (219 kg·hm^-2) + K₂O (219 kg·hm^-2)]}, and a control (CK, no irrigation and fertilization throughout the growing season). The nine irrigation and fertilization treatment combinations were W₁F₁, W₂F₁, W₃F₁, W₁F₂, W₂F₂, W₃F₂, W₁F₃, W₂F₃, and W₃F₃, respectively. The results indicated that different water and fertilizer regimes had no significant effect on the variation in diurnal photosynthetic indexes. However, the application of water and fertilizers considerably increased the peak value of net photosynthetic rate (P_n), exten-ded the stomatal opening period, influenced the lowest value of intercellular CO₂ concentration (C_i), and reduced the maximum value of water use efficiency (WUE) during the day. The limiting factors affecting photosynthesis were nonstomatal factors. Stomatal conductance (g_s) and transpiration rate (T_r) were both significantly negatively correlated with the distance from tree line (P<0.01). WUE were significantly positively correlated with the distance from the tree line (P<0.05). g_s decreased by 0.028-0.093 mol·m^-2·s^-¹, T_r decreased by 0.56-1.41 mmol·m^-2·s^-1, WUE increased by 0.08-1.00 μmol·mmol^-1, as the average distance from the tree line increased by 1 m. Thus, irrigation and fertilizers significantly increased the mean value of P_n, T_r, and g_s, but decreased the mean value of WUE during the day. The W₃F₁ treatment had the highest mean values of P_n(10.64 μmol·m^-2·s^-1), g_s(0.295 mol·m^-2·s^-1), WUE (3.05 μmol·mmol^-1), but a lower mean value of T_r(4.32 mmol·m^-2·s^-1) compared with the other treatment combinations during the day. When the total irrigation rate was 1300 m³·hm^-2, the total fertilization rate was 525 kg·hm^-2, P_n was at its maximum, and the theoretical maximum value was 10.32 μmol·m^-2·s^-1. Therefore, the W₃F₁ treatment was the irrigation and fertilizer regime that was most likely to improve the photosynthetic efficiency of the apple-maize intercropping system. 以晋西黄土区典型的苹果-玉米间作系统为研究对象,设置了双因素三水平水肥耦合试验,分析不同水肥调控措施下玉米灌浆期穗位叶光合生理特性.本试验根据玉米及苹果适宜的水分和养分条件设置9(3×3)个处理(W₁F₁、W₂F₁、W₃F₁、W₁F₂、W₂F₂、W₃F₂、W₁F₃、W₂F₃、W₃F₃),设置的3个灌溉水平为:田间持水量(Fc)的50％(W₁)、65％(W₂)和85％(W₃), 3个施肥量水平为:N 289 kg·hm^-2+ P₂O₅118 kg·hm^-2+ K₂O 118 kg·hm^-2(F₁)、N 412.4 kg·hm^-2 +P₂O₅168.8 kg·hm^-2 +K₂O 168.8 kg·hm^-2(F₂)、N 537 kg·hm^-2 + P₂O₅ 219 kg·hm^-2 +K₂O 219 kg·hm^-2(F₃),另设一组无水肥补给的空白对照(CK).结果表明: 不同水肥调控方式对光合指标日变化趋势无明显影响,但水肥补给可提高作物净光合速率(P_n)的峰值,降低作物日水分利用效率(WUE)最大值,延长气孔开放时间,影响胞间CO₂浓度(C_i)最低值的出现及维持时间;各处理光合作用的限制因素均为非气孔因素.蒸腾速率(T_r)、气孔导度(g_s)均与距树行距离呈极显著负相关(P<0.01),水分利用效率则与距树行距离呈显著正相关(P<0.05);距树行距离平均每增加1 m, T_r可减少0.56~1.41 mmol·m^-2·s^-1,g_s可减少0.028～0.093 mol·m^-2·s^-1,WUE可增加0.08~1.00 μmol·mmol^-1.灌水施肥可以显著提高净光合速率、蒸腾速率、气孔导度日均值;降低水分利用效率的日均值;W₃F₁拥有最高的净光合速率日均值(10.64 μmol·m^-2·s^-1)、水分利用效率日均值(3.05 μmol·mmol^-1)、气孔导度日均值(0.295 mol·m^-2·s^-1)以及较低的蒸腾速率日均值(4.32 mmol·m^-2·s^-1).多元回归分析结果显示,在拔节-灌浆期内,灌水总量为1300 m³·hm^-2、施肥总量为525 kg·hm^-2时,作物净光合速率最大,理论值为10.32 μmol·m^-2·s^-1.因此,W₃F₁为最利于间作系统作物光合效率改善的水肥调控模式.

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