Effects Of Zinc On Seedling Growth And Photochemical Efficiency Of Broccoli Seedlings

Broccoli（Brassica oleracea L.var.italica Plench）is a variety of cruciferae Brassica oleracea forgreen flower head as edible parts. Its flower head has bright color, fragrance flavor, rich nutrition, itranked first in Brassica vegetables, and enjoyed by people, the cultivated area is being expandedconstantly in recent years.Zinc is an essential trace element for crops, which has important influence on growth,development and yield of crops.With the improvement of agricultural production conditions and theincrease of crop yield, the consumption of Zn elements in soils also increase, Zinc deficiencybecame one of the important limiting factors restricting the growth and development of crop.Applying Zinc fertilizer has attracted widespread attention.This research, choosing broccoli"Jingyou"as the experiment material, studied the effects ofZinc on seed germination of broccoli and effects of Zinc on seedling growth and photochemicalproperties of broccoli seedlings under different temperature, in order to provide theoretical basis forbroccoli Zinc fertilizer application, obtained the following research results:1. The germination index of broccoli seed firstly rose and then dropped with the increasing ofZn²⁺concentration. The relative germination rate, vigor and germination index up to their maximumvalue all at100mg/L, while seed vigor index, radicle root length, bud root length and biomass at10mg/L. The Zn²⁺stress with200mg/L had the inhibiting effect on seed germination and growth ofbroccoli seeds.2. The Zn²⁺concentrations of5mg/L was the most suitable for the growth of broccoli seedlingsunder low temperature （15℃/10℃,20℃/15℃） treatment; Zn²⁺had no effect on the growth ofbroccoli seedlings under high temperature （35℃/15℃） treatment.3.0.5,5,10,50mg/L Zn²⁺showed a significant role in promoting the leaf number, plant height,stem diameter, leaf area, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight,fresh weight and dry weight of broccoli seedlings under different temperature.4. Deficiency of Zinc could dramatically inhibit the growth of leaf number, plant height, stemdiameter, leaf area, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, freshweight and dry weight of broccoli seedlings.5. When Zn²⁺concentrations higher than100mg/L, all of the growth index were significantlylower than those of other Zinc concentration at the same temperature, damage the broccoli seedlingplant obviously.6. Fv/Fm, ΦPSII, Fv’/Fm’ and qP of broccoli seedlings leaves up to their maximum value all atthe day/night temperature of25℃/15℃under different Zinc concentrations...