Influences of Drought and Microbial Water‐Retention Fertilizer on Leaf Area Index and Photosynthetic Characteristics of Flue‐Cured Tobacco

Abstract Drought has become a severe and frequently happening issue in the Guizhou province of China due to unevenly distributed rainfall and long‐term continuous cropping. Since drought and continuous cropping could be significant in causing the soil environment to deteriorate, measures which are beneficial for improving the growth of crops need are of great concern. In this study, drought conditions and a microbial water‐retention fertilizer (MWF) were applied as influencing factors for the leaf area index (LAI) and photosynthetic characteristics of flue‐cured tobacco. Under different drought conditions, the largest leaf area was obtained in normal conditions combined with 45 g basin −1 MWF (T13), which significantly increased by 32.0% when compared to normal conditions combined with 0 g basin −1 MWF (T1). An index model was further used to validate the above‐mentioned results and the correlation coefficients of LAI among different treatments were precisely simulated (0.981–0.993). The MWF had remarkable effects on tobacco's net photosynthetic rate ( P n ), stomatal conductance ( G s ), intercellular CO 2 concentration ( C i ) and transpiration rate ( T r ) . Furthermore, normal conditions (550 mm irrigation) combined with MWF (45 g basin −1 ) proved to be the preferable strategy for improving water use efficiency as well as the tobacco plantation. The results might provide theoretical and practical guidance for the growth of crops in areas with water shortage. © 2019 John Wiley & Sons, Ltd.