Studies on seedlessness of loquat fruit as related to endogenous plant hormone.

1.以枇杷二倍体茎尖为材料，采用甲基氨丙磷和秋水仙碱作为染色体加倍剂，获得了6个四倍体枇杷植株.四倍体与二倍体正反交产生的三倍体苗的比例为92%~ 100%。正反交间无显著差异.枇杷二倍体、三倍体和四倍体植株的叶宽、叶厚、气孔长、花萼最大直径、花瓣长、花瓣宽和花粉粒直径均随多倍体水平的提高而显著增加。二倍体和四倍体的花粉萌发率均高达95%。而在三倍体中，这一比例极低，仅为8%，结实率也极低，仅为0.1%。以1, 000 ppm-GA_3 + 20 ppm-CPPU在花期和花后60天左右分别施于花和果上2次，采收时座果率最高（92%）。单独施用CPPU或GA_3的坐果率分别为31%和53%。GA_3 + CPPU处理的坐果率和无核果大小随GA_3浓度的增加而线性增加。而CPPU处理的锤度下降。这主要是由于蔗糖含量的降低造成的.从枇杷未成熟种子中提取赤霉素类物质。采用ODS-HPLC法对各组分进行分级，并将各组分分别施用于二倍体枇杷的花和果实。5个处理均诱导出无籽果，但不同处理的坐果率不同.在采前60 ~ 20天，用1, 000 ppm-GA_3、20 ppm-CPPU、100 ppm-NAA、1, 000 ppm-ABA和400 ppm-Ethepone处理二倍体枇杷果实，GA_3和CPPU处理果实增大，Ethepone、CPPU和GA_3处理果实含糖量增加。而NAA处理则导致低糖、高酸。

1. Six tetraploid loquats were obtained by applying amiprofos-methyl and colchicine for chromosome doubling agents to diploid loquat shoot apex.2. The ratios of triploid seedlings produced by reciprocal crossing between tetraploids and diploids ranged from 92% to 100%. There were no great differences among the reciprocal crosses.3. Leaf width and thickness, stomata length, maximal diameter of calyx, petal length and width, and pollen grain diameter in the dr-, tri- and tetraploid plants significantly increased with increasing polyploidy level in loquats. The pollen germination ratios were high at 95% in both the diploid and the tetraploid. However, it was markedly low at 8% in the triploid, and the fructification was also extremely low at 0.1%.4. When 1,000ppm-GA_3 plus 20ppm-CPPU was applied to flowers and fruits two times at bloom and about 60 days after bloom of triploid loquat, the percentage of fruit set at harvest was highest (92%). On the other hand, Set of fruit applied with CPPU or GA_3 alone was 31% and 53%, respectively. Fruit set and Size of seedless fruit in the applications of GA_3 plus CPPU increased linearly with increasing GA_3 concentration. However, brix decreased in the treatments including CPPU. This cause depended on decrease of sucrose content.5. GA-like substances were extracted from immature seeds of loquat. After it was fractionated by ODS-HPLC, each fraction was applied to flowers and fruits of diploid loquat. Seedless fruits were induced in treatment of five fractions, but the percentage of fruit set varied among fractions.6. When 1,000ppm-GA_3, 20ppm-CPPU, 100ppm-NAA, 1,000ppm-ABA and 400ppm-ethepnone were applied to diploid loquat fruits during 60 to 20 days before harvest, fruit size in GA_3 and CPPU treatments, and sugar content in ethephone, CPPU and GA_3 treatments increased. However, NAA application resulted in low sugar and high acid contents.