Phosphorous Nutritional Level, Carbohydrate Reserves and Flower Quality in Olives

Abstract

The olive tree is generally characterized by relatively low final fruit set consequential to a significant rate of undeveloped pistils, pistil abortion, and flower and fruitlet abscission. These processes are acknowledged to be governed by competition for resources between the developing vegetative and reproductive organs. To study the role of phosphorus (P) nutritional level on reproductive development, trees were grown under four levels of P for three years in large containers. Phosphorus nutritional level was positively related to rate of reproductive bud break, inflorescence weight, rate of hermaphrodite flowers, pistil weight, fruitlet persistence, fruit set and the consequential total number of fruits. The positive impact of P nutrition on the productivity parameters was not related to carbohydrate reserves or to carbohydrate transport to the developing inflorescence. Phosphorous deficient trees showed significant impairment of assimilation rate, and yet, carbohydrates were accumulated in inflorescences at levels comparable to or higher than trees receiving high P. In contrast to female reproductive organs, pollen viability was consistently higher in P deficient trees, possibly due to the enhanced carbohydrate availability. Overall, the positive effect of P on female reproductive development was found to be independent of the total carbohydrate availability. Hence, P is speculated to have a direct influence on reproductive processes.

Sustainable Management of Olive Orchard Nutrition: A Review

“…Until recently, knowledge regarding the role of P in olive cultivation was very limited [43,50], and common practice suggested no P fertilization as long as leaf P levels were above 0.1%. Publications concerning the direct effect of P on olive productivity have been published only in the last decade [41,42,[51][52][53]. The lack of information is likely a result of the common belief that olive trees take up P very efficiently [25,26,50], due to their extensive root systems and symbiosis with mycorrhiza fungi [54,55].…”

“…Therefore, in contrast to broadcast application, P fertigation improves P availability and enhances the plants' potential to take up P rapidly when required [13,33]. Reports from controlled container experiments found that increased P levels have a direct positive effect on the whole reproductive cycle and contribute to an increase in yield [41,51].…”

Biomass and Phosphorus Accumulation and Partitioning of Geranium and Coleus in Response to Phosphorus Availability and Growth Phase

“…It appears that increasing P allocation to flowers is of primary importance under low-P for reproductive geranium plants to ensure reproductive success, however, increasing P allocation to roots of reproductive coleus plants indicates that excess P is stored primarily in the roots. Although direct evidence is missing to support this notion, it was reported that P deficient olive trees had higher pollen viability and accumulated carbohydrates in inflorescences at levels comparable to or higher than trees that received high-P despite having significantly impaired assimilation rate [43]. Furthermore, the shoot P concentration of reproductive coleus plants was lower than that of vegetative ones despite the higher P uptake ( Table 5), suggesting that lower tissue P concentration of reproductive coleus plants resulted from P dilution due to the accumulation of new biomass from the faster growth rate and greater leaf expansion [44].…”

Total Soluble Sugars Dynamics in Coffee Fruits Under Development

“…The carbohydrates, produced in leaves of the same season or stored in the plant reserves, are transported to the organs of the plant that cannot satisfy their energy requirement by themselves. These organs, like leaves, roots, branches and fruits, require carbohydrates to achieve their development potential (Erel et al, 2016;Haouari, Van Labeke, Steppe, & Mariem, 2013). However, if the carbohydrates supply is limited or demand is excessive (i.e., high fruit demand) there is a hierarchy of preferential supply to developing parts that is spatially and temporally dynamic among sinks (Reyes, DeJong, Franceschi, Tagliavini, & Gianelle, 2016).…”