AI can empower agriculture for global food security: challenges and prospects in developing nations.

Food and nutrition are a steadfast essential to all living organisms. With specific reference to humans, the sufficient and efficient supply of food is a challenge as the world population continues to grow. Artificial Intelligence (AI) could be identified as a plausible technology in this 5th industrial revolution in bringing us closer to achieving zero hunger by 2030-Goal 2 of the United Nations Sustainable Development Goals (UNSDG). This goal cannot be achieved unless the digital divide among developed and underdeveloped countries is addressed. Nevertheless, developing and underdeveloped regions fall behind in economic resources; however, they harbor untapped potential to effectively address the impending demands posed by the soaring world population. Therefore, this study explores the in-depth potential of AI in the agriculture sector for developing and under-developed countries. Similarly, it aims to emphasize the proven efficiency and spin-off applications of AI in the advancement of agriculture. Currently, AI is being utilized in various spheres of agriculture, including but not limited to crop surveillance, irrigation management, disease identification, fertilization practices, task automation, image manipulation, data processing, yield forecasting, supply chain optimization, implementation of decision support system (DSS), weed control, and the enhancement of resource utilization. Whereas AI supports food safety and security by ensuring higher crop yields that are acquired by harnessing the potential of multi-temporal remote sensing (RS) techniques to accurately discern diverse crop phenotypes, monitor land cover dynamics, assess variations in soil organic matter, predict soil moisture levels, conduct plant biomass modeling, and enable comprehensive crop monitoring. The present study identifies various challenges, including financial, infrastructure, experts, data availability, customization, regulatory framework, cultural norms and attitudes, access to market, and interdisciplinary collaboration, in the adoption of AI for developing nations with their subsequent remedies. The identification of challenges and opportunities in the implementation of AI could ignite further research and actions in these regions; thereby supporting sustainable development.

Testing effects of vapor pressure deficit on fruit growth: a comparative approach using peach, mango, olive, orange, and loquat.

Determining the influence of vapor pressure deficit (VPD) on fruit growth is a key issue under a changing climate scenario. Using a comparative approach across different fruit tree species may provide solid indications of common or contrasting plant responses to environmental factors. Knowing fruit growth responses to VPD may also be useful to optimize horticultural management practices under specific atmospheric conditions. Climate data to calculate VPD and fruit relative growth rates (RGR) by fruit gauges were monitored in peach at cell division, pit hardening and cell expansion stages; in two mango cultivars at cell division, cell expansion and maturation stages; in two olive cultivars, either full irrigated or rainfed, at early and late cell expansion stages; in 'Valencia' orange at early and late cell division stage, before and after mature fruit harvest; in loquat at cell expansion and maturation stages. At the fruit cell division stage, sensitivity of fruit growth to VPD seems to vary with species, time, and probably soil and atmospheric water deficit. 'Keitt' mango and 'Valencia' orange fruit growth responded to VPD in opposite ways, and this could be due to very different time of the year and VPD levels in the monitoring periods of the two species. At pit hardening stage of peach fruit growth, a relatively weak relationship was observed between VPD and RGR, and this is not surprising as fruit growth in size at this stage slows down significantly. A consistent and marked negative relationship between VPD and RGR was observed at cell expansion stage, when fruit growth is directly depending on water intake driving cell turgor. Another behavior common to all observed species was the gradual loss of relationship between VPD and RGR at the onset of fruit maturation, when fruit growth in size is generally programmed to stop. Finally, regardless of fruit type, VPD may have a significant effect on fruit growth and could be a useful parameter to be monitored for tree water management mainly when the cell expansion process prevails during fruit growth.

Physiological and Structural Responses to Prolonged Water Deficit in Young Trees of Two Olive Cultivars.

This study aimed to characterize the physiological and structural responses of potted one-year-old olive trees belonging to two olive cultivars­'Nocellara del Belice' and 'Cerasuola'­exposed to prolonged drought under greenhouse conditions. Two irrigation treatments based on evapotranspiration (ET) were imposed for 69 days, i.e., well-watered (WW, 100% ET) and drought-stressed (DS, 10−30% ET). Leaf stomatal conductance (gs), stem water potential (Ψstem), transpiration (E), photosynthetic capacity (Amax), water use efficiency (WUE), stem (Kstem) and root (Kroot) hydraulic conductance, trunk diameter variations (TDV), and leaf patch attenuated pressure fluctuations (pp, a proxy of the inverse of leaf turgor pressure) were measured in WW and DS trees at different stages of the experiment. Leaf gs did not significantly differ between cultivars under DS, whereas differences in Ψstem only became significant at the end of prolonged drought, when 'Nocellara del Belice' experienced Ψstem < −4 MPa. 'Cerasuola' trees expressed the best WUE under drought, although they were more susceptible to photoinhibition under optimal plant water status. Both cultivars tended to increase their Kstem at the end of the drought period. A marked reduction in Kroot occurred in 'Cerasuola' plants after prolonged drought; however, a similar mechanism was not observed in 'Nocellara del Belice'. The ratio between Kstem and Kroot exponentially increased towards the end of the prolonged drought period in both cultivars, but more markedly in 'Cerasuola'. TDV and pp trends suggested that 'Cerasuola' plants keep better plant water status under severe drought compared to 'Nocellara del Belice' by maintaining high leaf turgor and reduced trunk diameter fluctuations. These responses may be related to reduced cell wall elasticity and xylem vessel size and/or wall thickness­drought avoidance mechanisms. The Kstem/Kroot ratio can serve as an indicator of drought stress avoidance mechanisms to compare genotype-specific responses to drought stress.

Soil and Regulated Deficit Irrigation Affect Growth, Yield and Quality of 'Nero d'Avola' Grapes in a Semi-Arid Environment.

The present work studied the effect of two consecutive years of regulated deficit irrigation (RDI) compared to rain fed management on the vegetative growth, yield, and quality of 'Nero d'Avola' grapes. The trial was conducted separately in two soils (vertisol and entisol) located at the top and bottom hillside of the same vineyard. Vertisol was characterized by greater depth, organic matter, exchangeable K2O, and total N than entisol. RDI was based on an irrigation volume at 25% of estimated crop evapotranspiration (ETc) up to end of veraison and 10% of estimated ETc up to 15 days before harvest. Predawn water potential (PDWP) was used as indicator of plant water status and irrigation timing. No difference in irrigation management was evident between vertisol and entisol. Under Mediterranean climate conditions, RDI was able to enhance grape yield and vegetative growth, especially in vertisol, but it reduced berry titratable acidity and total anthocyanins. 'Nero d'Avola' showed to adapt to drought conditions in the open field. Both soil type and irrigation regimes may provide opportunities to obtain different 'Nero d'Avola' wine quality and boost typicality.

Detecting Mild Water Stress in Olive with Multiple Plant-Based Continuous Sensors.

A comprehensive characterization of water stress is needed for the development of automated irrigation protocols aiming to increase olive orchard environmental and economical sustainability. The main aim of this study is to determine whether a combination of continuous leaf turgor, fruit growth, and sap flow responses improves the detection of mild water stress in two olive cultivars characterized by different responses to water stress. The sensitivity of the tested indicators to mild stress depended on the main mechanisms that each cultivar uses to cope with water deficit. One cultivar showed pronounced day to day changes in leaf turgor and fruit relative growth rate in response to water withholding. The other cultivar reduced daily sap flows and showed a pronounced tendency to reach very low values of leaf turgor. Based on these responses, the sensitivity of the selected indicators is discussed in relation to drought response mechanisms, such as stomatal closure, osmotic adjustment, and tissue elasticity. The analysis of the daily dynamics of the monitored parameters highlights the limitation of using non-continuous measurements in drought stress studies, suggesting that the time of the day when data is collected has a great influence on the results and consequent interpretations, particularly when different genotypes are compared. Overall, the results highlight the need to tailor plant-based water management protocols on genotype-specific physiological responses to water deficit and encourage the use of combinations of plant-based continuously monitoring sensors to establish a solid base for irrigation management.

A Cultivar-Sensitive Approach for the Continuous Monitoring of Olive (Olea europaea L.) Tree Water Status by Fruit and Leaf Sensing.

Sustainable irrigation is crucial to reduce water use and management costs in modern orchard systems. Continuous plant-based sensing is an innovative approach for the continuous monitoring of plant water status. Olive (Olea europaea L.) genotypes can respond to drought using different leaf and fruit physiological and morphological mechanisms. This study aimed to identify whether fruit and leaf water dynamics of two different olive cultivars were differently affected by water deficit and their response to changes of midday stem water potential (Ψstem), the most common indicator of plant water status. Plant water status indicators such as leaf stomatal conductance (gs) and Ψstem were measured in the Sicilian olive cultivars Nocellara del Belice (NB) and Olivo di Mandanici (MN), in stage II and III of fruit development. Fruit gauges and leaf patch clamp pressure probes were mounted on trees and their raw data were converted in relative rates of fruit diameter change (RRfruit) and leaf pressure change (RRleaf), sensitive indicators of tissue water exchanges. The analysis of diel, diurnal and nocturnal fluctuations of RRfruit and RRleaf highlighted differences, often opposite, between the two cultivars under water deficit. A combination of statistical parameters extrapolated from RRfruit and RRleaf diurnal and nocturnal curves were successfully used to obtain significant multiple linear models for the estimation of midday Ψstem. Fruit and leaf water exchanges suggest that olive cultivar can either privilege fruit or leaf water status, with MN likely preserving leaf water status and NB increasing fruit tissue elasticity under severe water deficit. The results highlight the advantages of the integration of fruit and leaf water dynamics to estimate plant water status and the need for genotype-specific models in olive.

Water Deficit Affects the Growth and Leaf Metabolite Composition of Young Loquat Plants.

Water scarcity in the Mediterranean area is very common and understanding responses to drought is important for loquat management and production. The objective of this study was to evaluate the effect of drought on the growth and metabolism of loquat. Ninety two-year-old plants of 'Marchetto' loquat grafted on quince were grown in the greenhouse in 12-liter pots and three irrigation regimes were imposed starting on 11 May and lasting until 27 July, 2013. One-third of the plants was irrigated with 100% of the water consumed (well watered, WW), a second group of plants was irrigated with 66% of the water supplied to the WW plants (mild drought, MD), and a third group was irrigated with 33% of the water supplied to the WW plants (severe drought, SD). Minimum water potential levels of -2.0 MPa were recorded in SD plants at the end of May. Photosynthetic rates were reduced according to water supply (WW>MD>SD), especially during the morning hours. By the end of the trial, severe drought reduced all growth parameters and particularly leaf growth. Drought induced early accumulation of sorbitol in leaves, whereas other carbohydrates were not affected. Of over 100 leaf metabolites investigated, 9 (squalene, pelargonic acid, glucose-1-phosphate, palatinol, capric acid, aconitic acid, xylitol, lauric acid, and alanine) were found to be useful to discriminate between the three irrigation groups, suggesting their involvement in loquat metabolism under drought conditions. Loquat behaved as a moderately drought-tolerant species (limited stem water potential and growth reductions) and the accumulation of sorbitol in favor of sucrose in mildly-stressed plants may be considered an early protective mechanism against leaf dehydration and a potential biochemical marker for precise irrigation management.

Quality evaluation of extra-virgin olive oils from Sicilian genotypes grown in a high-density system.

Studying the sensory profile and chemical composition of monovarietal extra-virgin olive oils (EVOOs) is important to define and manage their quality and uniqueness. Chemical and sensory traits of olive oils from 14 minor Sicilian olive genotypes in comparison with oils from six major Sicilian and three international cultivars were analysed. Oils were extracted in 2015 from fruit of the 23 genotypes grown in an experimental orchard at a planting density of 1140 trees ha-1. Fatty acid composition, phenol composition, carotenoid content and antioxidant power were determined and analysed using univariate and multivariate procedures, in particular Nocellara Etnea along with carotenoid, phenol content and good sensory attributes, producing the best quality EVOO among the genotypes in trial. These results show that some Sicilian accessions used in this study may represent valid alternatives to produce high-quality EVOOs in modern, hedgerow planting systems.

Fruit and Leaf Sensing for Continuous Detection of Nectarine Water Status.

Continuous assessment of plant water status indicators provides the most precise information for irrigation management and automation, as plants represent an interface between soil and atmosphere. This study investigated the relationship of plant water status to continuous fruit diameter (FD) and inverse leaf turgor pressure rates (p p) in nectarine trees [Prunus persica (L.) Batsch] throughout fruit development. The influence of deficit irrigation treatments on stem (Ψ stem) and leaf water potential, leaf relative water content, leaf stomatal conductance, and fruit growth was studied across the stages of double-sigmoidal fruit development in 'September Bright' nectarines. Fruit relative growth rate (RGR) and leaf relative pressure change rate (RPCR) were derived from FD and p p to represent rates of water in- and outflows in the organs, respectively. Continuous RGR and RPCR dynamics were independently and jointly related to plant water status and environmental variables. The independent use of RGR and RPCR yielded significant associations with midday Ψ stem, the most representative index of tree water status in anisohydric species. However, a combination of nocturnal fruit and leaf parameters unveiled an even more significant relationship with Ψ stem, suggesting a changing behavior of fruit and leaf water flows in response to pronounced water deficit. In conclusion, we highlight the suitability of a dual-organ sensing approach for improved prediction of tree water status.

Deficit irrigation and maturation stage influence quality and flavonoid composition of 'Valencia' orange fruit.

BACKGROUND: Effects of continuous deficit irrigation (DI) and partial rootzone drying (PRD) treatments (50% ETc) in comparison with full irrigation (CI, 100% ETc) were investigated during 'Valencia' orange fruit maturation. Ultra-high-performance liquid chromatography/high-resolution mass spectrometry was used to quantify hesperidin, narirutin, tangeritin, nobiletin, didymin and neoeriocitrin in the fruit juice and peel. RESULTS: No significant effect of irrigation was found on yield, juice soluble solids or acidity. Juice color was not influenced by irrigation or harvest date, whereas peel color increased during maturation and was more pronounced in CI and PRD fruits. Juice acidity reached a peak in May, while soluble solids increased linearly throughout maturation. Hesperidin was the major flavanone detected during maturation, with concentrations 200-fold higher in the fruit peel than in the juice. In the peel, narirutin, didymin and neoeriocitrin decreased while hesperidin, nobiletin and tangeritin increased with maturation. Narirutin synthesis in the orange fruit was insensitive to irrigation strategy. In fruit peels, PRD and DI induced the decline of hesperidin, nobiletin and tangeritin only in June, whereas in the juice, deficit irrigation treatments induced an increase in hesperidin and didymin. CONCLUSION: These results suggest that deficit irrigation, in particular the conditions imposed with PRD, may cause a significant accumulation shift of total flavonoids from the fruit peel into the juice, with a positive impact on juice quality and nutritional value. Fruit compositional changes during maturation also suggest that late harvest can improve fruit palatability and nutritional quality under the cultural and environmental conditions of this study. © 2016 Society of Chemical Industry.

Huanglongbing modifies quality components and flavonoid content of 'Valencia' oranges.

BACKGROUND: In order to evaluate the effect of citrus greening disease, or Huanglongbing (HLB), on quality components and flavonoid contents of 'Valencia' oranges, fruit from non-infected trees (control), from infected trees but symptom-less (asymptomatic) and from infected trees and showing clear HLB symptoms (symptomatic) were harvested in March and in May, 2013. Fruit peel, pulp and juice were separated, the main quality components were determined, and hesperidin, nobiletin, tangeretin, narirutin and didymin were quantified using liquid chromatography. RESULTS: Peel colour, total soluble solids and citric acid were similar in control and asymptomatic fruits. Symptomatic fruits were smaller, yielded less juice, had higher acidity and lower sugar and peel colour than control fruits. In the peel, hesperidin, nobiletin, tangeretin, narirutin and didymin were higher in symptomatic than in asymptomatic and control fruits. Peel flavonoids decreased with fruit maturation. Also, in pulp and juice, flavonoid content was higher in symptomatic than in asymptomatic and control fruits. CONCLUSIONS: These results show that asymptomatic fruits are similar to control fruits more than to symptomatic fruits, suggesting that secondary metabolism and physical properties of fruits are only affected at a later and more advanced stage of HLB infection. Despite the significant loss of quality, fruit with clear HLB symptoms accumulate high quantities of flavonoids in peel and pulp.

Regular consumption of fresh orange juice increases human skin carotenoid content.

Dermal carotenoids are a good indicator of antioxidant status in the body. This study aimed to determine whether regular consumption of orange juice could increase dermal carotenoids. Two types of orange juice, obtained from regularly (CI) and partially (PRD) irrigated trees, were tested to reveal any possible association between juice and dermal carotenoids. Soluble solids, titratable acidity, and total carotenoids were quantified in the juice; skin carotenoid score (SCS) was assessed by Raman spectroscopy. Carotenoid content was 7.3% higher in PRD than in CI juice, inducing no difference in SCS. In a first trial with daily juice intakes for 25 days, SCS increased linearly (10%) in the individual with higher initial SCS, and exponentially (15%) in the individual with lower initial SCS. In a second trial, SCS showed a 6.5% increase after 18 days of drinking juice every other day, but returned to initial values three days after last intake. Skin carotenoids can be increased by regular consumption of fresh orange juice, while their persistence may depend on the accumulation level, environmental conditions or living habits.

Fruit physical, chemical and aromatic attributes of early, intermediate and late apricot cultivars.

BACKGROUND: In order to reach good fruit quality, apricots require a balance of sugars and acids as well as a strong apricot aroma. In this study, fruit quality of early, intermediate and late apricot cultivars was evaluated by measuring physical, chemical and olfactory attributes. Multivariate analysis of quality and aroma attributes was used to identify groups of similar cultivars and association with ripening season. RESULTS: Physical, chemical and aromatic attributes showed great variation among cultivars but no relation to ripening season. Aromatic profiles (34 volatiles) of fruit tissues indicated qualitative and quantitative differences among cultivars. Ninfa and Mandorlon were richest in aroma, with a prevailing fruity component; Goldrich and Orange Red were also highly aromatic, with all odour components well represented; Pinkot, Alba and Pellecchiella were lowest in aroma, with a prevailing grassy component. Linear functions including five volatiles (concentrations) and fruit diameter or six aromatic compounds (odour units) and peel colour were found to discriminate cultivars by ripening season. Principal component analysis individuated three groups of cultivars: Ninfa and Mandorlon with sweet and fruity-flavoured fruits; Bulida, Alba, Goldrich, Ouardy and Silvercot with large, acidic and well-coloured fruits; and Fracasso, Pellecchiella, Palummella and Pinkot with small and floral/grassy-flavoured fruits. CONCLUSION: In apricot, detailed analysis of the aromatic profile may represent an efficient tool for classification of genotypes by ripening season, and volatiles with relevant odour contribution may serve as quality markers for selecting towards an extended ripening season of best quality apricots.

Carbohydrate availability affects growth and metabolism in peach fruit.

Along with sucrose, sorbitol represents the main photosynthetic product and form of translocated carbon in peach. This study aimed at determining whether peach fruit carbohydrate metabolism is affected by changes in source-sink balance, and specifically whether sorbitol or sucrose availability regulates fruit enzyme activities and growth. In various trials, different levels of assimilate availability to growing fruits were induced in vivo by varying crop load of entire trees, leaf : fruit ratio (L:F) of fruiting shoots, or by interrupting the phloem stream (girdling) to individual fruits. In vitro, fruit tissue was incubated in presence/absence of sorbitol and sucrose. Relative growth rate (RGR), enzyme activities and carbohydrates were measured at different fruit growth stages of various peach cultivars in different years. At stage III, high crop load induced higher acid invertase (AI, EC 3.2.1.26) activities and hexose : sucrose ratios. Both sorbitol and sucrose contents were proportional to L:F, while sorbitol dehydrogenase (SDH, EC 1.1.1.14) activity was the only enzyme activity directly related to L:F in both fruit growth stages. Girdling reduced fruit RGR and all major carbohydrates after 4 days and SDH activity already after 48 h, but it did not affect sucrose synthase (SS, EC 2.4.1.13), AI and neutral invertase (NI, EC 3.2.1.27). Fruit incubation in sorbitol for 24 h induced higher SDH activities than in buffer alone. In general, assimilate availability affected both sorbitol and sucrose metabolism in peach fruit, and sorbitol may function as a signal for modulating SDH activity. Under highly competitive conditions, AI activity may be enhanced by assimilate depletion, providing a mechanism to increase fruit sink strength by increasing hexose concentrations.

Carbon autonomy of peach shoots determined by (13)C-photoassimilate transport.

We used (13)CO(2) tracing and source-sink manipulation to determine if fruiting shoots of peach (Prunus persica (L.) Batsch) trees are autonomous or if they import carbon from neighboring shoots, and if the degree of shoot autonomy is influenced by the source-sink relationship of the shoot. In three experiments, leaf to fruit ratio (L:F) of selected fruiting shoots was moderately (2005 and 2006) or strongly (complete sink removal, 2006) altered to either enhance or inhibit movement of carbon from (13)C-labeled fruiting shoots (LFS) to adjacent non-labeled shoots (NLFS), both located within 10 cm on the same main scaffold of V-shaped peach trees. At Stages I and III of fruit growth, fruit and shoot tips were sampled from LFS and NLFS to determine (13)C percentage on the day of labeling and after one week. Factors that differed among the three experiments in the two years were cultivar, tree age, source:sink ratios and labeling time. In all cases but one, no (13)C was found in fruits or shoot tips of NLFS. Only at Stage III of 'Redhaven' peach fruit growth (2005) was (13)C detected in fruits of NLFS, but only in the treatment favoring movement, and on the day of labeling. When L:F was altered to the maximum extent possible and branches were girdled at their base (complete sink removal, 2006), a detectable concentration of (13)C was recovered in fruits of NLFS at both growth stages, indicating that (13)C movement across adjacent shoots is possible, and detectable by (13)C tracing. According to our results, peach branches are relatively autonomous even at the fruiting-shoot level. However, conditions of strong imbalance between source supply and sink demand, either experimentally imposed or during periods of strong sink competition, may cause some movement of carbon among neighboring shoots.

Carbohydrate metabolism of vegetative and reproductive sinks in the late-maturing peach cultivar 'Encore'

Activities of NAD(+)-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) in 'Encore' peach (Prunus persica L.) fruits and developing shoot tips were assayed during the growing season to determine whether carbohydrate metabolizing enzymes could serve as indicators of sink strength. In fruit flesh, SS activity was detected during Stage I of growth, when cells were actively dividing, and SDH activity was detected during Stage III, when cells were actively enlarging. Acid invertase activity was detected during Stage I and showed a closer correlation with relative increase in fruit weight during the growing season than SS activity. During seed filling and pit hardening (Stage II), when relative fruit growth rate was slowest, activities of carbohydrate metabolizing enzymes in fruit flesh were not detectable. No SOX activity was detected during Stages I and II. The highest sucrose content occurred near the end of fruit development when the activities of sucrose metabolizing enzymes were low. In developing shoot tips, the sorbitol:sucrose ratio was 2:1 (w/w) and SDH activity was low at the beginning and end of the season when vegetative growth was slowest. The sorbitol:sucrose ratio changed to 1:1 (w/w) along with an increase in SDH activity in shoot tips during the mid-growing season. In 'Nemaguard' peach, SDH exhibited higher activity in root tips than in other organs. Among the sorbitol- and sucrose-metabolizing enzyme activities, only SDH activity was positively correlated with shoot growth in 'Nemaguard' plants.