Growth characteristics and morphology differences between bisexual flowers and functionally male flowers of‘Tunisia’pomegranate

Abstract: 【Objective】Pomegranate has two kinds of flowers on a same plant: functional male flowers（FMF）and bisexual flowers（BF）. BFs have well-formed pistils and can set fruits，thus they are knownas female fertile（vase-shaped）. FMFs，which are referred as female sterility（bell-shaped），fail to setfruit and drop finally. The ratio of FMFs is in inverse ratio to the yield of fruit. High ratio of FMFs is one ofthe main factor that impact the yield of pomegranate. To study the morphology and growth characteristicsdifferences between bisexual flowers and functionally male flowers.【Methods】‘Tunisia’was used to studygrowth characteristics and morphology differences of bisexual flowers and functionally male flowers.【Results】The results indicated that（1）the ratio of bisexual flowers existed variances in different branchtypes. In annual long branch，the ratio of bisexual flowers was significantly lower than that in annual spur，annual meddle branch and perennial branch（P < 0.01）. However，there were no significant differenceamong annual spur，annual meddle branch and perennial branch.（2）The ratio of bisexual flowers was dif⁃ferent among different type flowers，flowers in cluster was noticeably fewer than in single and pair flowers （P < 0.01）. The number of bisexual flowers in terminal were more than lateral flowers in cluster flowers（P < 0.05）.（3）The ratio of bisexual flowers in fascicle phyllotaxis was higher than that in opposite phyl⁃lotaxis（P < 0.01）.（4）From the measurement of the various different indices for FMF and BF，we deter⁃mined differences in OTD，OVD，and SL as the growth of BVD between FMF and BF.The associations be⁃tween these parameters and the 17 distinct modules were then compiled“. single-organism process”（GO:0065007），“organic substance metabolic process”（GO:0071704），“biological regulation”（GO:0065007），“organic substance biosynthetic process”（GO:0044711），“small molecule metabolic process”（GO:0044281），“phosphate-containing compound metabolic process”（GO:0006796），“lipid metabolicprocess”（GO:0006629），“lipid biosynthetic process”（GO:0008610）and“organonitrogen compoundmetabolic process”（GO:1901564）were also enriched in these modules.（5）Pollen germination were ob⁃served in functionally male flowers. But they were less than that in bisexual flowers. Pollen tube can’t ex⁃tend to the bottom of style.【Conclusion】Breeding pomegranate spur type varieties can be an importantbreeding aim，because the ratio of bisexual flowers in spur was the highest. Moreover，the pollen can ger⁃minate in functionally male flowers’chapiter，but can’t elongate to the style. Which can pave the way forthe studying of mechanism of pomegranate female sterility.