HORTSCIENCE 54(3):487–491. 2019. https://doi.org/10.21273/HORTSCI13785-18 inflorescence primordium shrivel or abscise after sensing adequate cool temperature, resulting in generation of leafless inflores- Leafless Inflorescence Produces More cences. In contrast, rising temperatures dur- ing the initiation period of inflorescence Female Flowers and Fruit Yield Than primordium development will produce a leafy inflorescence with both rudimentary Leafy Inflorescence in ‘Yu Her Pau’ leaves and lateral inflorescences at the same node along the main inflorescence axis. In some instances, a vegetative/generative tran- Litchi sit shoot will be produced if low temperatures Yu-Chi Lee and Jer-Chia Chang1 followed by warm temperatures occur at the Department of Horticulture, National Chung-Hsing University, No.145, later stages of the inflorescence development (Chang, 1999; Chen, 1994; Chen et al., 2009; Xingda Road, Taichung 40227, Taiwan, Republic of China Lin, 1987; McConchie and Batten, 1991; Additional index words. flowering shoot, generative shoot, flush, cluster, fruit set, fruit quality Olesen et al., 2002; Zhou et al., 2008). The leafy flowering shoot has been the main leafy Abstract. The purpose of this study was to determine whether the total number and inflorescence type in Taiwan (Chang, 2017; percentage of female flowers and fruit yield were influenced by the type of inflorescence, Chang et al., 2009). i.e., leafless or leafy inflorescences in ‘Yu Her Pau’ litchi (Litchi chinensis Sonn.). Four 10- The leafy inflorescence in citrus has been year-old field-grown plants in Chunghua, Taiwan, were assessed between March and well recognized to produce better fruit set and June 2013. In total, 24 inflorescences comprising 12 each of leafless and leafy in- quality at harvest than the leafless inflores- florescences were investigated. Leaves of the leafy inflorescence, defined as the fourth cence (Goldschmidt, 2013; Hansen, 1969; successive flush, attained maturity before female flower anthesis on 16 Mar. 2013. Shoot Hass, 1949; Moss, 1970); however, little is diameter and leaf number on the flowering (fruiting) shoot, total number of flowers, and known about the subsequent performance of total and percentage of female flowers were recorded. Fruit number, fruit set rate, cluster leafy inflorescence in terms of fruit set in yield, and fruit quality were also determined at harvest between the two inflorescence litchi. It is generally assumed that the fruit set types. The two inflorescence types had similar shoot diameters and total leaf number on a on leafless inflorescences is better than on flowering shoot. The total number of flowers, female flowers, and the percentage female leafy inflorescences (Chang et al., 2009; flowers in leafless inflorescences were 3741, 563, and 16.2%, respectively; these values Davenport and Stern, 2005; Lee, 2008). were 1.3- to 1.7-fold higher (P £ 0.05) than those in leafy inflorescences, which were 2779, Leaves and lateral inflorescences synchro- 326, and 12.2%, respectively. Leafless inflorescences had significantly higher fruit nize their development within leafy inflores- numbers and fruit yield per cluster at harvest (10.2 and 321.5 g, respectively), although cence (Huang, 2005; Lee, 2014). These there was no difference (P > 0.05) in fruit set rate between the two inflorescence types. No young leaves have no net carbon assimilation fruit quality trait, such as fruit, pericarp, aril, seed weight, aril proportion, and total ability at the initial growth stage of the soluble solid concentration of aril, was significant (P > 0.05) between the two inflorescence inflorescence (Wang, 2014). In addition, the types. We concluded that leafless and leafy inflorescences of ‘Yu Her Pau’ had similar red and soft new leaves of the leafy inflores- carbon assimilation supply potential; however, leafless inflorescence had greater cence inhibit the differentiation of lateral performance in terms of female flower number and thus fruit yield, presumably due to inflorescences (Chen, 1990, 1994; Davenport, the absence of assimilate competition brought by synchronous development of lateral 2000), resulting in a decrease in the total inflorescence and immature leaves of panicle. number of flowers and female flowers, sub- sequently reducing fruit yield. Few studies have been carefully employed Litchi (Litchi chinensis Sonn.) is an im- proportion of leafy inflorescences in ‘Yu Her on the relationship between fruit set and portant fruit cultivated in the subtropical Pau’ has occurred frequently, and the manual inflorescence types in litchi. Litchi has three regions. ‘Yu Her Pau’, the main commercial removal of leaves from leafy inflorescences types of flower: male flower (M1), hermaph- cultivar of litchi worldwide, is well known has become a standard commercial practice, rodite flower functioning as female (female for its shriveled seed and high-quality taste, although it increases the costs of orchard flower, F), and hermaphrodite flower func- although it has an uneven fruit set from year management, while its benefits still need tioning as male (M2) (Chu et al., 2015; Wu to year (Chang and Lin, 2003, 2006; Chang confirmation (Chang et al., 2009). Therefore, et al., 2017). Kumar (2013) preliminarily et al., 2009; Jiang et al., 2012). Poor pollina- management of the leafy inflorescence has indicated that neither female flower percent- tion and fertilization as well as undesirable become the new issue of the litchi industry age nor fruit set rate was influenced by the photo-assimilate supply–demand between (Chang, 2017). appearance of leafy inflorescence in ‘Shahi’ the sink and source organs result in high Vegetative and flowering shoots are ho- litchi; however, in comparison with the leaf- physiological fruit drop in litchi (Menzel, mologous organs (Li, 2008). The litchi shoot less inflorescence, the 40% to 60% decrease 1984; Mustard, 1960; Roe et al., 1997; Sauco apical meristem initiates inflorescence pri- in the total number of flowers and female and Menini, 1989; Yuan and Huang, 1988). mordia, comprising leaf and floral primordia flowers resulted in an 50% decrease in yield In response to recent climate change, as a result of cool-temperature induction of the leafy inflorescence. In contrast, Chen particularly global warming, the increasing (Batten and McConchie, 1995; Li, 2008). et al. (2014) reported that the percentage of The flowering shoot of litchi has a character- leafy inflorescence and number of fruit set istic of flush cycles, and the process of of ‘Yu Her Pau’ litchi increased when 100 –1 inflorescence initiation and flower develop- mg·L GA3 was sprayed onto the foliage Received for publication 3 Dec. 2018. Accepted for ment in a flowering shoot is sensitive to during quiescence period; however, the per- publication 5 Jan. 2019. temperature (Stern and Gazit, 2003), which centage of female flowers, cluster yield, fruit Dr. Huey-Lin Lin and Dr. Cheng-Chin Chen are may form two types of flowering shoots set rate, and the residual effects of GA3 on gratefully acknowledged for their comments on an subsequently in terms of leafless (generative) the leafy inflorescences and fruit were not earlier version of this manuscript. This study was and leafy inflorescences. The latter, by their partially supported by a grant from Ministry of documented in this study. Whether leafy Science and Technology, Executive Yuan, Taiwan, leaves and inflorescence relative position, inflorescences impose a major burden or Republic of China (to Jer-Chia Chang). can be sorted into leafy and vegetative/ reduction of the subsequent fruit set and fruit 1Corresponding author. E-mail: changjerchia@ generative transit shoots (Davenport and development normally in litchi was inconsis- yahoo.com.tw. Stern, 2005). Rudimentary leaves within the tent from their results. HORTSCIENCE VOL. 54(3) MARCH 2019 487 The purpose of this study was to deter- number of leaves of flowering shoots of two Flower number and type in the inflorescence. mine whether the different inflorescence inflorescence types were measured to dem- M1 has a rudimentary pistil surrounded by types affect flowering and fruiting perfor- onstrate whether the carbon assimilation stamens with hair-like filaments, and the ovary mance in terms of flower and fruit number, supply potential was consistent. Next, the contains two ovules with no embryo sac. Con- yield, and quality at harvest in field-grown inflorescence quality was assessed in terms of versely, M2 has a pistil with a style and ovary ‘Yu Her Pau’ litchi plants. The diameter and the total number of flowers and female surrounded by stamens with filaments. However, flowers and percentage female flowers within the lobes of the stigma do not open for each inflorescence. Finally, to understand the pollination at anthesis. Both M1 and M2 have influence of the leafy inflorescences on fruit anthers that open at anthesis. In contrast, F has a production, the fruit number, fruit set rate, fully developed pistil with a functional stigma cluster yield, and fruit quality at harvest were with fruiting potential at anthesis (Mustard also calculated. The results from our research et al., 1953; Robbertse et al., 1995). In addition may prompt changes in the management to the three types of flowers mentioned, flower strategy of litchi orchards with regard to buds for which the sex could not be confirmed flowering and fruit production and thus pro- were counted as ‘‘others.’’ vide information on defoliation of leafy in- The sequence of flower opening on ‘Yu florescences in the future. Her Pau’ litchi inflorescence in this study was in the order of F, M1, and M2 in 2013. To Materials and Methods collect all the flowers, the experimental in- florescences were enclosed by meshed silk Plant materials and inflorescence sampling. bags (35 · 35 · 70 cm3,20· 30 mesh/inch2) The experiments were conducted at a 10- from the beginning of blooming of female year-old ‘Yu Her Pau’ litchi orchard flowers on 16 Mar. 2013 (Chang and Lin, (lat. 24°01#N, long. 120°64#E) in Chunghua 2003; McConchie and Batten, 1991). How- County, central Taiwan, between March and ever, the meshed silk bags were removed June 2013.