The Effect Of Paclobutrazol On The Growth Development Of Broccoli Seedlings

Broccoli?B.oleracea L.var.italica?was popular due to rich nutritional substances and potential anticarcinogenic properties.During the period of seedling of broccoli in summer,it is easy to form into leggy seedlings due to the environment of high temperature and high humidity,which could affect the quality of the seedlings and the subsequent growth and yield formation.The measures of temperature and humidity control would spend high cost,for example the method of factory seedlings which is suitable for a large number of seedling.Paclobutrazol(PP₃₃₃),a plant growthregulator,is currently widely used in vegetable seedling,which has significant inhibition effect on leggy seedling.In thepresent paper,seedlings of broccoli have been treated by using different concentration at different growth period with PP₃₃₃1,and the corresponding morphological and physiological indexes were determined.The main conclusions are as follows:1.When be treated with PP₃₃₃,the stem length,stem diameter and dry weight of broccoli seedlings demonstrated significant difference with control.Spraying 25 mg/LPP₃₃₃ resulted in higher effect on the dwarf of seedlings,and 50 mg/L and 100mg/L substantially increased the stem diameter of seedlings.At the same time,50 mg/LPP₃₃₃ significantly enhanced the dry weight,which it was increased by about 1.7-fold.2.PP₃₃₃ treatment improved the content of chlorophyll,and 50 mg/L PP₃₃₃ revealed the best efficiency,which showed the change trend of relatively flat than the control.3.The content of soluble sugar in leaves showed a trend of falling after rising,and 150 mg/L PP₃₃₃ resulted in higher content compared to control.4.High concentrations of PP₃₃₃ treatment could obviously increase the content of soluble protein in the leaves.Especially at the late period of seedlings,the higher concentration present poorer effect,25 mg/L and 50 mg/L could effectively delay the degradation of protein.5.25 mg/L PP₃₃₃ significantly improved the activity of SOD and POD in leaves of broccoli seedling,thus maintaining the ability of scavenging free radicals and stabilizing the permeability of cell membrane.50mg/L significantly enhanced activity of CAT.6.The content of MDA during the growth period of broccoli seedling showed ascendant trend,200 mg/L PP₃₃₃ significantly decreased the content of MDA,which would help to improve the resistance of seedlings.7.The content of free proline in leaves showed a trend of rising after falling.25 mg/L and 50 mg/L significantly increased the content of free proline at the early stage of seedling growth,and 50 mg/L achieved the best effect at the late stage.