南酸枣花芽形态分化过程及叶片营养生理特性

Morphological Differentiation Process of Flower Buds and Nutritional and Physiological Characteristics in Leaves of Choerospondias axillaris

【目的】探究南酸枣花芽分化的外部形态变化与内部解剖结构的对应关系,揭示叶片中营养物质动态变化与花芽分化进程的关系。【方法】采用石蜡切片法观察南酸枣花芽;测定分化关键期叶片可溶性蛋白、可溶性淀粉、可溶性糖、全磷、全氮、全钾、有机质含量变化。【结果】1)南酸枣的花类型为单花类型或聚伞圆锥花序,雄花为花序,雌花为花序或单花。南酸枣花芽多为混合芽,成年雄树花芽萌发率达99%,雌树花芽萌发率达70%。2)南酸枣花芽分化可划分为9个时期:未分化期、生理分化期、苞片形成期、萼片形成期、花序形成期、花瓣形成期、雄蕊形成期、雌蕊形成期、侧花序发育期。南酸枣花芽分化从3月底开始,2月下旬芽萌动后约40天进入生理分化期,6月中下旬为雌雄原基分化盛期,翌年3月,雌、雄花的侧花序发育完全。3)花芽横、纵径的增长呈现先快后慢的趋势,生理分化期雌、雄花芽横径较未分化期分别提高了211.36%和231.11%,生理分化期南酸枣花芽体积处于快速增加期;花序形成期雌、雄花芽横径较花萼形成期分别提高了5.43%和10.00%,生长速度变缓。4)芽基叶片可溶性蛋白含量于花序形成期具最低值,雌、雄叶片中可溶性蛋白和可溶性淀粉含量均于花序形成期达峰值,分别为2.29、2.51和25.43、21.50 mg·g^(−1);花序形成期雌、雄叶片氮的含量降幅大,相较未分化期分别下降了22.88%和32.51%,全氮含量下降25.35%和34.09%,全磷含量下降41.07%和39.67%,全钾含量下降23.94%和22.52%。雌花芽叶片的碳氮比值范围在21.01~26.52,雄花芽范围在21.14~28.90。【结论】南酸枣自芽萌发至雌、雄蕊原基始分化约需4个月,雌花生理分化进程晚于雄花10天左右,花序发育完全约需1年时间。叶片中高含量的氮、磷、钾元素有利于花芽的生理分化,较高的碳氮比可调节南酸枣花芽的形态分化过程;叶片需积累较多的可溶性糖及可溶性淀粉有利于花序形成;生理分化期(4月下旬)和花序分化期(6月上旬)是花芽分化进程中较关键的时期,南酸枣高效水肥管理及花果调控应着重关注这两个时期。

【Objective】This study aims to explore the corresponding relationship between external morphological changes and anatomical structures in the differentiation process of Choerospondias axillaris flower buds,and reveal the relationship between the dynamic changes of nutrients in leaves and the differentiation process of flower buds.【Method】The paraffin section method was used to observe the flower buds of C.axillaris,and the contents of soluble protein,soluble starch,soluble sugar,total phosphorus,total nitrogen,total potassium,and organic matter in the leaves near the bud were determined at key differentiation stages.【Result】1)The flower type of C.axillaris was thyrse or solitary,with the male flower as inflorescence,and the female flower as inflorescence or solitary.Most of the flower buds of C.axillaris were mixed buds,with a sprouting rate of 99%for adult male trees and 70%for female trees.2)The differentiation of C.axillaris flower buds can be divided into 9 stages:undifferentiated stage,physiological differentiation stage,bract formation stage,sepal formation stage,inflorescence formation stage,petal formation stage,stamen formation stage,pistil formation stage,and lateral inflorescence developing stage.The differentiation of C.axillaris flower buds started at the end of March.After bud sprouts in late February,it took about 40 days to enter the physiological differentiation stage.The mid to late June was the peak period for the differentiation of the female and male primordia of flower buds.In early March of the following year,lateral inflorescences of both female and male flowers were fully developed.3)The growth of horizontal and vertical diameters of flower buds showed a trend of first fast and then obviously slow.The horizontal diameter of female and male flower buds in the physiological differentiation stage increased by 211.36%and 231.11%,respectively,compared to the undifferentiated stage,and the size of flower buds was rapidly rising.Transverse diameters of female and male flower buds in the inflorescence formation stage increased by 5.43%and 10.00%,respectively,compared to the sepal formation stage,suggesting that growth rate slowed down.4)The soluble protein contents in leaves on the bud base dropped to its lowest in inflorescence primordia differentiation stage,while the contents of soluble protein and soluble starch in female and male leaves reached their peeks in inflorescence primordia differentiation stage,with the values of 2.29 and 2.51,25.43 and 21.50 mg·g^(−1),respectively.During the inflorescence formation stage,the nitrogen content in female and male leaves decreased significantly,with a decrease of 22.88%and 32.51%,respectively,compared to the undifferentiated stage.The total nitrogen contents decreased by 25.35%and 34.09%,and the total phosphorus contents decreased by 41.07%and 39.67%,the total potassium contents decreased by 23.94%and 22.52%,respectively,compared to the undifferentiated stage.The carbon nitrogen ratio of female flower bud leaves ranged from 21.01 to 26.52,while male flower bud leaves ranged from 21.14 to 28.90.【Conclusion】It takes about 4 months from the sprouting of the buds to the initial differentiation of pistil and stamen primordia of C.axillaris,and inflorescences are fully developed at the following year of March.The physiological differentiation process of female flowers is about 10 days later than that of male flowers.The nutrients in the leaves proximate to flower bud have great changes in physiological differentiation period.The high contents of nitrogen,phosphorus and potassium in the leaves are conducive to the physiological differentiation of flower buds,and higher carbon-nitrogen ratio can regulate the morphological differentiation process of C.axillaris.During the inflorescence formation period,the leaves need to accumulate more soluble sugar and soluble starch.The physiological differentiation stage(in late April)and inflorescence differentiation stage(in early June)are the most critical periods,when a special attention should paid to effcient irrigation and fertilization management and fruit yield regulation of C.axillaris.