Morpho-anatomical determinants of yield potential in Olea europaea L. cultivars belonging to diversified origin grown in semi-arid environments

Abstract

Plant performance is mainly estimated based on plant architecture, leaf features and internal microstructural changes. Olive (Olea europaea L.) is a drought tolerant, oil yielding, and medium sized woody tree that shows specific structural and functional modifications under changing environment. This study was aimed to know the microstructural alteration involving in growth and yield responses of different Olive cultivars. Eleven cultivars were collected all over the world and were planted at Olive germplasm unit, Barani Agricultural Research Institute, Chakwal (Punjab) Pakistan, during September to November 2017. Plant material was collected to correlate morpho-anatomical traits with yield contributing characteristics. Overall, the studied morphological characters, yield and yield parameters, and root, stem and leaf anatomical features varied highly significantly in all olive cultivars. The most promising cultivar regarding yield was Erlik, in which plant height seed weight and root anatomical characteristics, i.e., epidermal thickness and phloem thickness, stem features like collenchymatous thickness, phloem thickness and metaxylem vessel diameter, and leaf traits like midrib thickness, palisade cell thickness a phloem thickness were the maximum. The second best Hamdi showed the maximum plant height, fruit length, weight and diameter and seed length and weight. It also showed maximum stem phloem thickness, midrib and lamina thicknesses, palisade cell thickness. Fruit yield in the studied olive cultivars can be more closely linked to high proportion of storage parenchyma, broader xylem vessels and phloem proportion, dermal tissue, and high proportion of collenchyma.

Fig 1. Root transverse sections of Olea europaea L. cultivars planted at Barani Agricultural Research Institute, Chakwal.

Fig 2. Stem transverse sections of Olea europaea L. cultivars planted at Barani Agricultural Research Institute, Chakwal.

Fig 3. Leaf transverse sections of Olea europaea L. cultivars planted at Barani Agricultural Research Institute, Chakwal.

Fig 4

Relationship of yield parameters with a) growth, b) root anatomical, c) stem anatomical and d) leaf anatomical traits of Olea europaea cultivars planted at Barani Agricultural Research Institute, Chakwal. Morphology: PH: Plant height, TC: Trunk circumference, NL: Number of leaves per branch, NF: Number of fruits per branch (Lowest branch), LL: Leaf length, LW: Leaf width, LA: Leaf area, FL: Fruit length, FD: Fruit diameter, FW: Fruit weight, SW: Stone weight, SL: Stone length, SD: Stone diameter, FY: Fruit yield. Root anatomy: RCS-Root cross sectional area, RET-Epidermal thickness, RCT-Cortical region thickness, RCA-Cortical cell area, RST-Sclerenchymatous thickness, ROT-Collenchymatous thickness, RPT-Phloem thickness, RMA-Metaxylem vessel diameter, RPA-Pith cell area. Stem anatomy: SCS-Stem cross-sectional area, SET-Epidermal thickness, SCT-Cortical region thickness, SCA-Cortical cell area, SST-Sclerenchymatous thickness, SOT-Collenchymatous thickness, SPT-Phloem thickness, SMA-Metaxylem vessel diameter, SPA-Pith cell area. Leaf anatomy: LMT-Midrib thickness, LLT-Lamina thickness, LST-Spongy cell thickness, LPT-Palisade cell thickness, LUT-Cuticle thickness, LDT-Adaxial epidermal thickness, LBT-Abaxial epidermal thickness, LMA-Metaxylem vessel diameter, LHT-Phloem thickness, LCT-Parenchymatous region thickness, LCA-Parenchymatous cell area.

Fig 5

Response of a) growth, b) root anatomical, c) stem anatomical and d) leaf anatomical traits with fruit yield of Olea europaea cultivars planted at Barani Agricultural Research Institute, Chakwal. Morphology: PH: Plant height, TC: Trunk circumference, NL: Number of leaves per branch, NF: Number of fruits per branch (Lowest branch), LL: Leaf length, LW: Leaf width, LA: Leaf area, FL: Fruit length, FD: Fruit diameter, FW: Fruit weight, SW: Stone weight, SL: Stone length, SD: Stone diameter, FY: Fruit yield. Root anatomy: RCS-Root cross sectional area, RET-Epidermal thickness, RCT-Cortical region thickness, RCA-Cortical cell area, RST-Sclerenchymatous thickness, ROT-Collenchymatous thickness, RPT-Phloem thickness, RMA-Metaxylem vessel diameter, RPA-Pith cell area. Stem anatomy: SCS-Stem cross-sectional area, SET-Epidermal thickness, SCT-Cortical region thickness, SCA-Cortical cell area, SST-Sclerenchymatous thickness, SOT-Collenchymatous thickness, SPT-Phloem thickness, SMA-Metaxylem vessel diameter, SPA-Pith cell area. Leaf anatomy: LMT-Midrib thickness, LLT-Lamina thickness, LST-Spongy cell thickness, LPT-Palisade cell thickness, LUT-Cuticle thickness, LDT-Adaxial epidermal thickness, LBT-Abaxial epidermal thickness, LMA-Metaxylem vessel diameter, LHT-Phloem thickness, LCT-Parenchymatous region thickness, LCA-Parenchymatous cell area.

Fig 6

Heatmaps showing clustering of yield parameter with a) growth, b) root anatomical, c) stem anatomical and d) leaf anatomical traits of Olea europaea cultivars planted at Barani Agricultural Research Institute, Chakwal. Morphology: PH: Plant height, TC: Trunk circumference, NL: Number of leaves per branch, NF: Number of fruits per branch (Lowest branch), LL: Leaf length, LW: Leaf width, LA: Leaf area, FL: Fruit length, FD: Fruit diameter, FW: Fruit weight, SW: Stone weight, SL: Stone length, SD: Stone diameter, FY: Fruit yield. Root anatomy: RCS-Root cross sectional area, RET-Epidermal thickness, RCT-Cortical region thickness, RCA-Cortical cell area, RST-Sclerenchymatous thickness, ROT-Collenchymatous thickness, RPT-Phloem thickness, RMA-Metaxylem vessel diameter, RPA-Pith cell area. Stem anatomy: SCS-Stem cross-sectional area, SET-Epidermal thickness, SCT-Cortical region thickness, SCA-Cortical cell area, SST-Sclerenchymatous thickness, SOT-Collenchymatous thickness, SPT-Phloem thickness, SMA-Metaxylem vessel diameter, SPA-Pith cell area. Leaf anatomy: LMT-Midrib thickness, LLT-Lamina thickness, LST-Spongy cell thickness, LPT-Palisade cell thickness, LUT-Cuticle thickness, LDT-Adaxial epidermal thickness, LBT-Abaxial epidermal thickness, LMA-Metaxylem vessel diameter, LHT-Phloem thickness, LCT-Parenchymatous region thickness, LCA-Parenchymatous cell area.

Fig 7. Pearson’s correlation coefficients between mophological and anatomical traits of Olea europaea L. culltivers at p>0.001, 0.01 and 0.05 levels.

Legends: a. between root and stem anatomy, b. between root and leaf anatomy, c. between stem and leaf anatomy, d. between morphological traits: RCS-Root cross sectional area, RET-Epidermal thickness, RCT-Cortical region thickness, RCA-Cortical cell area, RST-Sclerenchymatous thickness, ROT-Collenchymatous thickness, RPT-Phloem thickness, RMA-Metaxylem vessel diameter, RPA-Pith cell area. SCS-Stem cross-sectional area, SET-Epidermal thickness, SCT-Cortical region thickness, SCA-Cortical cell area, SST-Sclerenchymatous thickness, SOT-Collenchymatous thickness, SPT-Phloem thickness, SMA-Metaxylem vessel diameter, SPA-Pith cell area. LMT-Midrib thickness, LLT-Lamina thickness, LST-Spongy cell thickness, LPT-Palisade cell thickness, LUT-Cuticle thickness, LDT-Adaxial epidermal thickness, LBT-Abaxial epidermal thickness, LMA-Metaxylem vessel diameter, LHT-Phloem thickness, LCT-Parenchymatous region thickness, LCA-Parenchymatous cell area; PH: Plant height, TC: Trunk circumference, NL: Number of leaves per branch, NF: Number of fruits per branch (Lowest branch), LL: Leaf length, LW: Leaf width, LA: Leaf area, FL: Fruit length, FD: Fruit diameter, FW: Fruit weight, SW: Stone weight, SL: Stone length, SD: Stone diameter, FY: Fruit yield.