Study On The Botanical Characteristics And Physiological And Biochemical Of Different Ploidy Cucumber

Cucumber has important economic value,and it is one of the favorite vegetables.It has been cultivated for a long history.In recent years,with the increase of cultivation area,people needs high variety quality,new cucumber germplasm resources are urgently needed.The utilization of polyploid can solve the problem of long breeding cycle.Polyploid plants have the characteristics of strong growth,increased stress resistance,increased fruit and high nutrient content,so it can be used to improve the quality and stress resistance of cucumber,so as to improve cucumber yield.In this study,based on the common diploid?2n=2x=14?,triploid?2n=3x=21?,tetraploid?2n=4x=28?cucumber as material,study the morphology,anatomical structure of leaf and stem,photosynthetic characteristics,stress resistance and the other aspects,to explore the basic characteristics of polyploid physiological and biochemical aspects,so through the research on the search for new materials of cucumber breeding.The results of this study could not only enrich the cucumber germplasm resources,but also provide a material for breeding high yield and high quality cucumber varieties.The main results were as follows:1.There were great difference in external morphology of cucumber with different ploidy.Compared with diploid cucumber,the tetraploid cucumber had thicker and hypertrophy cotyledon and leaf,the stems and petioles became coarser,leaf and petal and seeds became larger,fruit increased;for the triploid cucumber its cotyledon and leaf became larger,stems and petioles thickened,its male flower petals increased,seed increased,but its ovary and fruit weight had no significant change.2.The anatomical structures of different ploidy cucumber was different.With the increase of ploidy,the leaf thickness,thickness of upper epidermis and lower epidermis thickness,palisade tissue,spongy tissue,palisade spongy ratio and petiole epidermis thickness,cortex thickness,vascular bundle area,the number of vessels and the thickness of epidermis and the stem cortex thickness,vascular area all increased.3.The photosynthetic characteristics of different ploidy cucumber was different.The chlorophyll content in per unit leaf area calculation increased with the increase of ploidy,the chlorophyll a,chlorophyll b,total chlorophyll and carotenoid content were highest in tetraploid plant,but lowest in diploid plant.The diurnal light variation curve of net photosynthetic rate of different ploidy cucumber show the bimodal type,there were midday depression phenomenon,the peaks appeared at about 10:00 and 13:00,the second peak is less than the first peak.The Pn of triploid plant was the highest,the Pn of tetraploid plant was the lowest.4.The dyeing rate and germination rate of tetraploid pollen were only 68.8% and 43.6%,while dyeing rate and germination rate of the diploid were about 94.4% and 80.6%,their differences were significantly.5.The contents of Vitamin C,soluble sugar,soluble protein and amino acid of triploid and tetraploid cucumber fruit were higher than these of diploid,which showed that the nutrient content of polyploid cucumber was higher than that of diploid.6.The fruit setting rate and number of single melon seeds of the diploid were higher than these of tetraploid.When the tetraploid as male parent and diploid as female parent,the fruit setting rate and number of single melon seeds were relatively high,on the contrary number of single melon seeds was relatively low.7.Compared with diploid cucumber F₁,the early yield and total yield of the triploid cucumber F₁ were increased by 33.70% and 22.69%.The difference was significant.The commodity traits of the triploid F₁ were better than those of diploid,thus the triploid cucumber F₁ was more suitable for the cucumber production.8.The resistance of the different ploidy cucumber was different.The resistances of tetraploid plant to powdery mildew and downy mildew were higher than those of triploid,otherwise,the resistances of triploid were higher than those of diploid.The resistant ability of tetraploid and triploid plant to low temperature was higher than that of diploid.