26 Apr 2024
Citrus Fruiting

Effects of Water-deficit Stress and Gibberellic Acid on Floral Gene Expression and Floral Determinacy in ‘Washington’ Navel Orange

Effects of water-deficit stress and foliar-applied gibberellic acid (GA3) on ‘Washington’ navel orange (Citrus sinensis) floral gene expression and inflorescence number were quantified. Trees subjected to 8 weeks of water-deficit stress [average stem water potential (SWP) −2.86 MPa] followed by 3 weeks of re-irrigation (SWP recovered to > −1.00 MPa) produced more inflorescences in week 11 than trees well-irrigated (SWP > −1.00 MPa) for the full 11 weeks (P < 0.001). After 8 weeks of water-deficit stress, bud expression of flowering locus t (FT), suppressor of overexpression of constans1 (SOC1), leafy (LFY), apetala1 (AP1), apetala2 (AP2), sepallata1 (SEP1), pistillata (PI), and agamous (AG) increased during the re-irrigation period (weeks 9 and 10), but only AP1, AP2, SEP1, PI, and AG expression increased to levels significantly greater than that of well-irrigated trees.


25 Nov 2022
Regulated deficit irrigation Clementina de Nules

Long-term response of ‘Clementina de Nules’ citrus trees to summer regulated deficit irrigation

Regulated deficit irrigation (RDI) has been assessed in a wide number of fruit crops. However, few are the studies dealing with long-term RDI strategies. In this work, we assessed the response of ‘Clementinade Nules’ citrus trees to summer RDI treatments [RDI-1, irrigated at 50% of crop evapotranspiration (ETc)and RDI-2, irrigated at 35% ETc] during six consecutive seasons (2007–2012). Although water restrictions were applied according to reductions over ETc, threshold values of stem water potential (−1.3 to −1.5 MPain the RDI-1 treatment and −1.5 to −1.7 MPa in the RDI-2) were also considered for scheduling deficitirrigation. Results showed that the water stress imposed in the RDI-2 treatment had a noticeable impacton fresh fruit weight, reducing yield and economic return over the six years and more so during the first two years in comparison to a control treatment irrigated at 100% ETc during the whole season. The RDI-1strategy had a lower impact than the RDI-2 treatment on the fresh fruit weight and did not significantly reduce yield or the economic return over the six seasons.