Effect of Plant Growth Substances on Morphological and Anatomical Structure of Leaf and Photosynthetic Characteristics in Soybean

Abstract

Many soybean [Glycine max(L.) Merr.] morphological and physiological regulations responding to plant growth substances have been reported.Related researches showed that plant growth substances could effectively control lodging,increase leaf area index,promote photosynthesis,reduce productive abscission and improve yield and quality in soybean production.Plant growth substances through adjusting inner hormone control soybean's whole process of growth and development,at the same time possibly affect the structure of soybean organs,including root,stem,leaf,and productive organs,on which there are a little report.Microtechnique and ultramicrotechnique have triumphantly applied in the researches on the changes of fibre texture and ultrastructure in plant caused by nutrient elements and environment factors,which provides availibility to research the effects of plant growth substances on the structure of soybean organs.The present study was carried out in an attempt to compare anatomi-cal structure and photosynthetic characteristics of cultivar Kennong 4,treated with three plant growth substances in the field of experiments on trail farm of Heilongjiang August-First Land Reclamation University in 2006.The selected secure plant growth substances Diethyl anlinoethyl(DTA),Ckolirte chloride(Cc),and SOD simulation material(SODM),were applied by leaf-spraying at the beginning of blossom stage(R1).30 days later,at the beginning seed stage(R5),the functional leaves were sampled to compare fibre texture and ultrastructure by microtechnique and ultramicrotechnique.Photosynthetic characteristics,such as leaf index,photosynthetic pigment content,photosynthetic potential and photosynthetic rate,were measured every 10 days after the treatments.The results indicated that the plant growth substances caused the changes of both anatomical structure of leaf and photosynthetic characteristics.Under light microscope,we found that,compared with control,DTA,CC,and SODM increased palisade tissue thickness and ratio of palisade/spongy of leaf.The tight degree of palisade tissue arrangement,was different in treatment showing the order of SODM DTA CC CK.DTA,CC,and SODM increased the number of chloroplast single cell,granule lamella and starch grains in chloroplast,while reduced the number of osmophilic globuli in the chloroplast.SODM,DTA increased granule number in chloroplast significantly.In the investigation of photosynthetic characteristics,we found that,compared with control,DTA,SODM,and CC increased the contents of Chl a,Chl b,Chl(a+b) in leaf and the ratio of Chl b/a.DTA,SODM,and CC advanced the time to maximum leaf area index and leaf area duration(LAD),increased total LAD and photosynthetic rate during grain filling period under water stress.From above,we drew a conclusion that plant growth substances could at least partially regulate the structure of soybean organs,fibre texture and ultrastructure of soybean leaf,which is helpful to promote photosynthesis,showing the consistency between anatomical structure and physiological function.