Factors influencing fecundity in experimental crosses of water lotus (Nelumbo nucifera Gaertn.) cultivars

Pollen viability of the individual cultivars ranged from 4.1% to 20.2%, with the highest level (>11.9%) for all cultivars observed from the earliest collected grains (05:00–06:00？a.m.). Stigmatic pollen germination peaked at 4？h after pollination and varied from 4.8 to 60.6 grains per stigma among the crosses. Production of normal embryos ranged from 7.6% to 58.8% at 1 d after pollination and from 0 to 25% by 11 d after pollination. Seed set in crosses (0.2–23.3%) was generally lower than in open-pollinated plants (8.4–26.5%). Similar to the germination results, seed set was substantially reduced in both reciprocal crosses.These results suggested that poor pollen fertility, low stigma receptivity, and embryo abortion were responsible for the failure of the crosses ‘Molingqiuse’？×？‘Qinhuaiyanzhi’, ‘Qinhuaiyanzhi’？×？‘Molingqiuse’, and ‘Aijiangnan’？×？‘Guili’.The Nelumbonaceae is a family of perennial, aquatic, herbaceous angiosperms, consisting of the two species Nelumbo nucifera Gaertn. and N. lutea (Willd.) Pers. Nelumbo nucifera, also called the Indian or sacred lotus, is found throughout Asia and Australia, whereas N. lutea, also known as the American lotus or water chinquapin, occurs in eastern and southern North America [1,2]. Fossilized leaves of N. nucifera show that wild populations were distributed previously in eastern Asia including China, India and Japan about 50 million years ago. Wild populations of N. nucifera in China are now mainly distributed in the provinces of Helongjiang, Jilin, and Sandong. Nelumbo nucifera was cultivated in China more than 2000？years ago. The current main cultivation areas in China comprise the provinces of Jiangsu, Zhejiang, Hubei, Anhui, Guangdong, Hunan, Fujian, and Jiangxi. This species is propagated vegetatively by rhizomes in commercial cultivation, and by seeds for breeding purposes [3]. As an economically important aquatic plant in China, N. nucifera cultivars are classified into three groups: rhizome lotus, seed lotus a