以江苏南京地区广泛栽培的薄壳山核桃〔Carya illinoinensis （Wangenh.） K. Koch〕品种‘波尼’（‘Pawnee’）、‘马罕’（‘Mahan’）、‘威奇塔’（‘Wichita’）、‘斯图尔特’（‘Stuart’）、金华’（‘Jinhua’）和‘绍兴’（‘Shaoxing’）为研究对象，对果实发育过程中果实形状以及果实横切面和纵切面的结构进行观察，并对果实质量、果核质量、种仁质量、出仁率、果实横径、果实纵径和果形指数7个指标进行分析。结果显示：6个薄壳山核桃品种的果实发育期历时149~169 d，均可分为缓慢生长期（约60 d）、快速膨大期（40~45 d）、硬核期（30~45 d）和种仁成熟期（10~15 d）4个时期，但6个品种果实发育各时期的持续时间略有差异。缓慢生长期果实的质量和横径增长较慢，纵径增长较快；快速膨大期果实的质量、横径和纵径均增长较快；硬核期胚乳逐渐硬化，果实质量小幅增长，果核质量基本不变，外果皮不断加厚；种仁成熟期果实的质量和大小基本稳定，外果皮出现分离或脱落的现象。6个品种的果实形状可分为狭倒卵状（‘马罕’）、倒卵状（‘威奇塔’）、卵状（‘波尼’和‘金华’）和近椭球状（‘斯图尔特’和‘绍兴’），其果形指数总体依次减小。随果实的生长发育，薄壳山核桃果实的质量、横径和纵径总体呈逐渐增大的趋势，而果形指数总体呈减小的趋势；从硬核期中期至种仁成熟期，种仁质量和出仁率总体呈先逐渐升高后降低的趋势。总体上看，6个品种中，‘马罕’、‘金华’和‘波尼’的果实质量、果核质量、种仁质量和出仁率的最大值均较大，‘绍兴’果实的这4项指标的最大值均最小；‘波尼’的果实横径最大，‘马罕’的成熟果实纵径最大。经过综合分析，6个品种在南京地区的最佳采收期应该在9月底至10月初；‘波尼’和‘马罕’可作为南京地区主栽品种的优选对象。

Taking cultivar ‘Pawnee’， ‘Mahan’， ‘Wichita’， ‘Stuart’， ‘Jinhua’， and ‘Shaoxing’ of Carya illinoinensis （Wangenh.） K. Koch widely cultivated in Nanjing of Jiangsu as research objects， fruit shape and fruit structures of transverse section and longitudinal section during fruit development process were observed， and seven indexes including fruit mass， nut mass， kernel mass， kernel rate， fruit transverse diameter， fruit longitudinal diameter， and fruit shape index were analyzed. The results show that fruit development periods of six cultivars of C. illinoinensis last for 149-169 d， and can be divided into four stages of slow-growth stage （about 60 d）， rapid expansion stage （40-45 d）， core-harden stage （30-45 d）， and kernel mature stage （10-15 d）， but the duration of each fruit development stage of six cultivars is slightly different. At slow-growth stage， fruit mass and transverse diameter grow relatively slow， but longitudinal diameter does relatively fast； at rapid expansion stage， fruit mass， transverse diameter， and longitudinal diameter all grow relatively fast； at core-harden stage， endosperm gradually hardens， fruit mass grows slightly， nut mass is almost invariant， and exocarp keeps thickening； at kernel mature stage， fruit mass and size are basically stable， and exocarp appears separation or abscission phenomenon. Fruit shape of six cultivars can be classified into narrowly obovate （‘Mahan’）， obovate （‘Wichita’）， oviform. （‘Pawnee’ and ‘Jinhua’）， and almost ellipsoidal （‘Stuart’ and ‘Shaoxing’）， and their fruit shape indexes successively decrease in general. With the growth and development of fruit， fruit mass， transverse diameter， and longitudinal diameter of C. illinoinensis show a tendency of gradual increase， while fruit shape index shows a tendency of decrease in general； from mid stage of core-harden to kernel mature stage， kernel mass and kernel rate show a tendency of first gradual increase and then decrease in general. In general， among six cultivars， the maximum of fruit mass， nut mass， kernel mass， and kernel rate of ‘Mahan’， ‘Jinhua’， and ‘Pawnee’ are all relatively large， while those of ‘Shaoxing’ are all the smallest； fruit transverse diameter of ‘Pawnee’ is the largest， while longitudinal diameter of mature fruit of ‘Mahan’ is the largest. Taken together， the optimum harvest period of six cultivars in Nanjing should be from the end of September to early October； ‘Pawnee’ and ‘Mahan’ can be selected as optimal objects of main cultivars in Nanjing.