Trancoso Ingrid, de Souza Guilherme A R, de Souza João Vitor Paravidini, Miranda Rosana Maria Dos Santos Nani de, Neves Diesily de Andrade, Rakocevic Miroslava, Campostrini Eliemar
Setor de Fisiologia Vegetal, Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense (UENF), Avenida Alberto Lamego 2000, Parque Califórnia, Campos dos Goytacazes 28013-602, RJ, Brazil.
Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy.
Plants (Basel). 2025 Aug 7;14(15):2445. doi: 10.3390/plants14152445.
Plant genders could express different functional strategies to compensate for different reproductive costs, as females have an additional role in fruit and seed production. Secondary sexual dimorphism (SSD) expression is frequently greater under stress than under optimal growth conditions. The early gender identification in papaya may help to reduce orchard costs because the most desirable fruit shape is formed by hermaphrodite plants. We hypothesized that (a) gender ecophysiological phenotyping can be an alternative to make gender segregations in papaya seedlings, and (b) such gender segregation will be more efficient after a short drought exposure than under adequate water conditions. To test such hypotheses, seedlings of two papaya varieties ('Candy' and 'THB') were exposed to two kind of treatments: (1) water shortage (WS) for 45 h, after which they were well watered, and (2) continuously well-watered (WW). Study assessed the ecophysiological responses, such as stomatal conductance (), SPAD index, optical reflectance indices, morphological traits, and biomass accumulation in females (F) and hermaphrodites (H). In WS treatment, the SSD was expressed in 14 of 18 traits investigated, while in WW treatment, the SSD was expressed only in 7 of 18 traits. As tools for SSD expression, and simple ratio pigment index (SRPI) must be measured on the first or second day after the imposed WS was interrupted, respectively, while the other parameters must be measured after a period of four days. In some traits, the SSD was expressed in only one variety, or the response of H and F plants were of opposite values for two varieties. The choice of the clearest responses of gender segregation in WS treatment will be greenness index, combination of normalized difference vegetation index (CNDVI), photochemical reflectance index (PRI), water band index (WBI), SRPI, leaf number, leaf dry mass, and leaf mass ratio. If the WW conditions are maintained for papaya seedling production, the recommendation in gender segregation will be the analysis of CNDVI, carotenoid reflectance index 2 (CRI2), WBI, and SRPI. The non-destructive optical leaf indices segregated papaya hermaphrodites from females under both water conditions and eventually could be adjusted for wide-scale platform evaluations, with planned space arrangements of seedlings, and sensor's set.
植物的性别可能会表现出不同的功能策略来补偿不同的繁殖成本，因为雌性在果实和种子生产中具有额外的作用。次生性别二态性（SSD）在胁迫条件下的表达通常比在最佳生长条件下更为明显。番木瓜的早期性别鉴定可能有助于降低果园成本，因为最理想的果实形状是由雌雄同株植物形成的。我们假设：（a）性别生态生理表型分析可以作为番木瓜幼苗性别分离的一种替代方法；（b）与充足水分条件下相比，经过短期干旱处理后进行这种性别分离会更有效。为了验证这些假设，对两个番木瓜品种（“Candy”和“THB”）的幼苗进行了两种处理：（1）缺水处理45小时，之后充分浇水；（2）持续充分浇水。研究评估了雌性（F）和雌雄同株（H）植株的生态生理响应，如气孔导度、SPAD指数、光学反射指数、形态特征和生物量积累。在缺水处理中，所研究的18个性状中有14个表现出SSD，而在充分浇水处理中，18个性状中只有7个表现出SSD。作为SSD表达的工具，气孔导度和简单比率色素指数（SRPI）必须分别在缺水处理中断后的第一天或第二天进行测量，而其他参数必须在四天后进行测量。在某些性状中，SSD仅在一个品种中表现出来，或者两个品种的H和F植株的响应值相反。在缺水处理中，最明显的性别分离响应选择将是绿度指数、归一化差异植被指数组合（CNDVI）、光化学反射指数（PRI）、水波段指数（WBI）、SRPI、叶片数量、叶片干质量和叶质量比。如果在番木瓜幼苗生产中保持充分浇水条件，性别分离的建议将是分析CNDVI、类胡萝卜素反射指数2（CRI2）、WBI和SRPI。无损光学叶片指数在两种水分条件下都能将番木瓜雌雄同株与雌性区分开来，最终可以针对大规模平台评估、幼苗的规划空间布局和传感器设置进行调整。
