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• The germination of cannabis treatments varied with landrace and treatments. • H 2 SO 4 , GA 3 , and KNO 3 enhanced the germination capacity of cannabis landraces. • Control produced vigorous seedlings compared dormancy-breaking pre-treatments. The current study evaluated the effectiveness of different pre-treatments for dormancy breaking and seed germination of five cannabis landraces. These landraces were collected from local growers in three regions of KwaZulu-Natal Province in South Africa, namely, Bergville (B), Hammersdale (H), and Ladysmith (L). Each genotype was assigned an alphabet and number based on where the seed material was collected. The five landraces were as follows, 'B1', 'K1', 'H1', 'L1', and 'L2'. The study was conducted using various pre-treatments, including potassium nitrate (KNO 3), hydrochloric acid (HCL), hot water (HW) at 70 °C, nitric acid (HNO 3), dry prechilling at 10 °C, gibberellic acid (GA 3), sulfuric acid (H 2 SO 4), and water, which served as the control. Before the germination test, the seed viability of cannabis landraces was assessed using the tetrazolium chloride (TCC) test. Afterward, the seeds were germinated in Petri dishes with cotton pads moistened with distilled water for five (5) days. The study was later validated under tunnel conditions. The parameters such as germination percentage, germination rate, seedling length, and seed vigour index of the germinated seeds were then measured. The landraces, dormancy breaking treatments, and their interactions showed significant differences (p < 0.001) in germination percentage, germination rate index, seedling length, and seed vigour index under both laboratory and tunnel conditions. In summary, GA 3 , KNO 3 and prechilling were the most effective pre-treatments to improve the germination and seedling growth of cannabis genotypes and breaking seed dormancy. Therefore, it was concluded that cannabis genotypes had physiological dormancy. [ABSTRACT FROM AUTHOR]

Effect of canopy position on rind biochemical properties of 'Marsh' grapefruit during postharvest non-chilling cold storage was evaluated on fruit harvested from different orchard locations. Inside canopy (IC) and outside canopy (OC) fruits were harvested at commercial maturity from two commercial farms located at KwaZulu-Natal (KZN) and Limpopo (LMP), South Africa, during two seasons. Rind biochemical analyses including color indices, total phenolic concentration, and sugars were performed on harvested grapefruit after Weeks 0, 3, 6, and 9 of cold storage at 7.5 ± 0.5°C. Canopy position showed a high significant (p <.001) effect on rind biochemicals while significant (p <.05) influence of orchard locations was observed on the same parameters. Reducing sugars were more concentrated in IC fruit harvested from both orchard location than OC fruit at Weeks 0 and 3, but inverse results occurred at Weeks 6 and 9. Orchard location significantly (p <.001) influenced vitamin C (14.4, 14.2, 14.4, 14.8 g kg−1) and (12.3, 16.1, 15.9, 14.6 g kg−1) of fruit rind at Weeks 0, 3, 6, and 9 from KZN and LMP, respectively. This study revealed that canopy position can influence rind biochemical properties of 'Marsh' grapefruit during non-chilling postharvest cold storage. However, further studies are required to formulate and provide the citrus industries with adequate advice. [ABSTRACT FROM AUTHOR]

• Photosynthetic efficiency of leaves from different positions of avocado trees was assessed. • Outside leaves had higher photosynthetic rate and stomatal conductance. • The high photosynthetic efficiency of outside fruit was linked fruit maturity. • Outside fruit matured earlier with mesocarp DM content of 23.2% compared to 22.3% on inside fruit. Physiological changes associated with leaf chlorophyll fluorescence and gas exchange are the key components towards understanding performance of fruit trees. In this study, the photosynthetic efficiency of leaves from inside and outside canopy positions of avocado trees was assessed during the fruit growing season. The aim was to determine to what extent photosynthesis and gas exchange of the leaves correlates with the position of the leaf inside canopy and outside canopy of an avocado tree, and how does that affect fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa during 2017/18 season. A total of fifteen 8-year old avocado trees (cv. 'Carmen') were selected in a completely randomised design with three replicates and each replicate consisting of five trees. Data was collected bi-weekly from full bloom to fruit physiological maturity (25% dry matter content). Measured variables included gs, C i, T , A , F 0 , F m , Fv/Fm , ΦPS II , qP, qN, ETR, 1- qP and DM content, were estimated within and outside canopy. Results showed that leaves from the outside position had higher A (22.28 mol CO 2 m−2 s−1) , gs (0.22 mol CO 2 m−2 s−1) , ΦPS II (0.35), and qP (0.57) compared to those on the inside position of the canopy with lower values of 14.19 mol CO 2 m−2 s−1, 0.14 mol CO 2 m−2 s−1, 0.047 and 0.071, for A, gs, ΦPS II and qP respectively. Conversely, Fo', Fm' , Fv', Fv'/Fm' , and 1- qP were about two times higher on the inside canopy than on the outside. The high photosynthetic efficiency of outside fruit was linked fruit maturity with fruit from the outside maturing earlier with an average mesocarp dry matter content of 27.6% compared to 26.5% on fruit from the inside canopy. The findings suggest that the high sunlight interception by leaves from the outside position improved photosynthetic efficiency, increased rate of dry matter accumulation and maturation of avocado fruit. There is a strong sink demand within the outside canopy demanding more carbohydrates, and thus commanding leaves from the outside canopy to photosynthesize more efficiently leading to fast maturity. [ABSTRACT FROM AUTHOR]

• The effect of canopy position on biochemical compounds regulating avocado maturity and ripening was evaluated. • Outside fruit had higher dry matter (DM) and oil content resulting in earlier maturity. • Higher concentrations of C7 sugars were recorded on inside canopy fruit, coinciding with late maturity and ripeness. • The minimum maturity of fruit from the inside canopy guarantees the maturity of outside canopy fruit. In the current study, biochemical changes of avocado fruit cv. 'Carmen' and 'Hass' were evaluated during growth, development and maturation. The aim was to determine if exposure of fruit to sunlight could vary the biochemical compounds associated with maturity, and hence be among the causes of uneven maturity, and ripening. The current study also seeks to evaluate if the mesocarp C7 sugars, oil and DM content have a relationship with fruit maturity. The study was conducted in a commercial orchard at Everdon Estates in the KwaZulu-Natal, South Africa. Nine avocado fruit (cv. 'Carmen' and 'Hass' avocado) per canopy were sampled bi-weekly for assessment of mesocarp dry matter (DM), oil content, D -mannoheptulose, perseitol and total C7 sugars. The significantly (p < 0.001) higher DM and oil content in fruit that were sampled from the outside canopy in both cultivars suggested an early maturity, and vice versa inside canopy. The higher D- mannoheptulose and perseitol in fruit sampled inside canopy as a storage reserve was associated with the rate of respiration, which is slower inside canopy due to cooler temperatures. This results in accumulation of higher overall C7 sugars that are slowly used up as a substrates of respiration for synthesis of overall DM, oils, proteins, C6 sugars and other biochemical constituents associated with ripening. In terms of maturity, higher D -mannoheptulose and perseitol implies that fruit from the inside canopy will take longer to mature and to reach edible ripeness when harvested. This then causes uneven maturity of fruit, only characterized by uneven ripening. [ABSTRACT FROM AUTHOR]

• Photoprotection mechanisms of avocado leaves from tree canopy positions were assessed. • Photochemistry was high outside of and low within the tree canopy. • Photoprotection mechanisms were stronger within the canopy and poorer outside the canopy. • High photochemistry outside the canopy was linked to early fruit maturity. • High chlorophyll fluorescence and heat dissipation within the canopy delayed fruit maturity. A reduction in photosynthesis results in a reduced CO 2 assimilation rate and availability of carbohydrates essential for fruit growth and development. This study determined photosynthetic efficiency and photoprotection mechanisms within and outside leaf canopy positions in 'Gem' avocado orchards and their relationship with avocado fruit maturity. The study was conducted in a commercial orchard at Everdon Estate in KwaZulu-Natal, South Africa. A total of 15 eight-year-old avocado trees (cv. Gem) were selected in a completely randomised design with three replicates, with each replicate consisting of five trees. Data were collected bi-weekly on photosynthetic rate (A), effective quantum efficiency of photosystem II (ϕPSII), stomatal conductance (gs), transpiration rate (T), electron transport rate (ETR), minimum fluorescence (Fo'), maximum fluorescence (Fm'), variable fluorescence (Fv'), intrinsic water use efficiency (WUE i), instantaneous water use efficiency (WUE ins), intercellular CO 2 concentration (Ci) and photochemical quenching (qP) from full bloom to fruit physiological maturity (∼25 % dry matter content (DM)). The results showed that leaves from the outside position had higher A (29.46 mol CO 2 m−2s-1); gs (0.078 mol CO 2 m−2s-1); ΦPS II (0.32); and qP (0.52) compared to those within the canopy position with lower A (19.27 mol CO 2 m−2s-1); gs (0.0037 mol CO 2 m−2s-1); ΦPS II (0.044) and qP (0.075), respectively. Contrastingly, chlorophyll fluorescence and photoprotection parameters were higher within the canopy than on the outside, suggesting that the greater proportion of energy accumulated within the canopy was used for photoprotection other than photochemistry. Photosynthetic rate (A) , gs, Ci, T, WUEi and WUE ins , correlated significantly with mesocarp dry matter (DM), while all other parameters correlated poorly. The high photosynthetic efficiency of leaves from outside the canopy resulted in an average DM of 28.9 % compared to 26.9 % of fruit within the canopy. The present findings suggest that reduced photosynthetic efficiency of 'Gem' avocado within the canopy position does not compromise fruit DM by reserving more energy for photoprotection; however, it delays maturity by about two weeks. [ABSTRACT FROM AUTHOR]