北方烟区水肥一体化对烤烟生长、根系形态、生理及光合特性的影响

干旱抑制北方烟区烤烟的生长发育,造成烟叶产量、质量下降。为探讨北方烟区水肥一体化对烤烟田间生长、根系形态生理和光合特性的影响,以‘云烟87’为试验材料,研究了烤烟农艺性状、干物质积累量、根系形态和生理活性、光合作用、叶绿素荧光特性以及烤后烟叶经济性状在水肥一体化和沟灌常规施肥2个不同处理下的差异。结果显示,与沟灌常规施肥处理相比,水肥一体化能够促进烤烟生长发育,使田间农艺性状表现良好。水肥一体化能够明显提高根系和地上部干物质积累量,降低根冠比,显著增加根系体积、总吸收面积、活跃吸收面和比表面积以及根系活力、ATPase等相关根系形态和生理活性(P0.05)。在水肥一体化下,烤烟叶片的光合作用指标净光合速率(P_n)、气孔导度(Gs)、胞间CO_2浓度(C_i)和水分利用效率(WUE)以及叶绿素荧光参数PSⅡ最大光化学效率(Fv/Fm)、实际光化学量子效率(ΦPSⅡ)和光化学淬灭系数(q_p)均显著高于沟灌常规施肥(P0.05),而蒸腾速率(T_r)、非光化学淬灭系数(NPQ)则明显较低(P0.05);同时,其烤后烟叶的经济性状显著高于沟灌常规施肥处理(P0.05)。研究表明,水肥一体化可以创造良好的根系形态,提高根系生理活性,增强光合作用和光能利用效率,从而促进烤烟生长发育,有助于提高烤后烟叶的经济性状。

Effects of water and fertilizer integration on growth,morphology,physiology and photosynthetic characteristics of flue-cured tobacco in the North China

Drought stress inhibits the growth and development of flue-cured tobacco in the North China, resulting in lower yield and quality. The purpose of this study was to determine the effects of integration of water and fertilizer on the growth and development, root morphology and physiology, and on photosynthetic characteristics of flue-cured tobacco in the North China. The differences in agronomic attributes, dry matter accumulation, root morphology and physiology, photosynthesis, chloro-phyll fluorescence and economic characteristics of 'Yunyan 87' flue-cured tobacco grown under water and fertilizer integration, and conventional irrigation and fertilization were investigated. The results showed that compared with conventional irrigation and fertilization, the growth and development of flue-cured tobacco was significantly promoted under water and fertilizer in-tegration and with better agronomic attributes. The integration of water and fertilizer significantly increased dry matter accu-mulation in the belowground and aboveground parts of the plant. It also improved the indices for root morphology and physi-ology in terms of root volume, total root absorption area, root active absorption area, root specific surface area, root activity and ATPase activity. All these attributes were significantly higher than those under conventional irrigation and fertilization. The integration of water and fertilizer also reduced root to shoot ratio (P< 0.05). Meanwhile, net photosynthetic rate (Pn), stomatal conductance(Gs), intercellular CO2concentration(Ci), water use efficiency (WUE), PSII maximal photochemical effi-ciency (Fv/Fm), PSII actual photochemical efficiency (ΦPSⅡ)and photochemical quenching coefficient (qP) all significantly in-creased under the integration of water and fertilizer (P< 0.05). On the contrary, both transpiration rate (Tr) and non-photochemical quenching coefficient (NPQ) significantly decreased under the integration of water and fertilizer (P< 0.05). Furthermore, the economic characteristics were significantly higher under the integration of water and fertilizer than those under conventional irrigation and fertilization (P< 0.05). In conclusion, the results indicated that the integration of water and fertilizer supported good root morphology and significantly improved root physiology activity, photosynthesis and light energy utilization efficiency. This stimulated the growth and development of flue-cured tobacco, resulting in higher economic characteristics.