Creation Of Autotetraploid Broccoli And Studies On Its Biological Characteristics

In this paper, it was studied the induction and identification of autotetraploid broccoli as well as its agronomic characteristics, photosynthetic and seeding characteristics, which laid theoretical and practical basis for cultivation and breeding of polyploid broccoli.1 Creation of autotetraploid broccoliAutotetraploid plants of broccoli were induced by treating the apical portion of seedling with different dilute solution of colchicines and further cytological and morphological analysis were made on these materials. Results showed that treatment with 0.1 g/100mL colchicines for 4 times yielded the highest autotetraploid-induced rates (15%). Compared with diploid plants, autotetraploid plants were characterized by larger stomata cells, more starch grains in stomata cells, less stomata density , larger pollen grains, more different shapes of pollen grains, more weight of overground part, longer stem diameter, less leaves, more weight of mean leaves, wider leaves, more weight of spear, larger flowers, and larger pods.2 Agronomic characteristics and nutritional quality of autotetraploidbroccoliAgronomic characteristics and nutritional quality were studied in both diploid and autotetraploid broccoli. Results showed that the autotetraploid had more height of plant, longer stem diameter, less leaves and more width and weight of the largest leaf than the diploid. The increase of the number and weight of different grades of lateral spears mainly resulted in the increase of the weight of main spear of autotetraploids. The soluble protein and sugar content and the dissociative amino acid of the diploid were not as much as that of the autotetraploid, and other nutritional qualities demonstrated non-significant difference between them.4 vegetative characteristics and 6 spear characteristics of 4 autotetraploid broccoli inbred lines were studied by means of canonical correlation analysis. Results showed that the correlation coefficient of vegetative and spear characteristics were at the very significant level. The height of plant, weight of aerial part, number of 1 grade lateral spears, number of 2 grade lateral spears and weight of all 2 grade lateral spears were the main variables in agronomic and spear characteristics. The height of plant and the number of plant correlated with 6 spear characteristics positively though canonical variables as well as the width of plant and the weight aerial part negatively.3 Photosynthetic characteristics of autotetraploid broccoliDiurnal changes of net photosynthetic rate (Pn) showed that the Pn curve demonstrated a single peak, and the maximum Pn appeared at 11:00 in both diploid and autotetraploid. The autotetraploid had higher Pn. Correlation and path analyses showed that the photon flux density (PFD) and the transpiration rate (Tr) correlated with the Pn most, and they were main factors which effected the Pn.It studied the light-response curves, ultrastructure of chloroplast, as well as photosynthetic pigment content and photosynthetic product in both diploid and autotetraploid broccoli. Results showed that the autotetraploid had higher compensating point, higher apparent quantum yields and higher dark respiration rate. The ultrastructure of chloroplast showed that autotetraploid with more chloroplast per cell had more and thicker grana with well connecting than diploid. The photosynthetic pigment, starch and soluble sugar content of the diploid were not as much as that of the autotetraploid.4 Pollen vitality and seeding characters of autotetraploid broccoliPollen vitality and seeding characters of diploid and autotetraploid broccoli were compared through pollen-strained method, pollen germination in vivo and in vitro and different pollination combination. Results showed that pollen of autotetraploid plants exhibited low vitality and low germinating rate with much shorter and abnormal pollen tube. Pollen germinated less of hybrid and inbred autotetraploid and inbred diploid than that of hybrid diploid. The seed production index of 2 combinations of diploid was higher than that of autotetraploid, which produced much larger seed than diploid. The seed production index of inbred pollination combination of autotetraploid increased 63.1% in 2005 compared with 2004.