Worldwide, it has been recorded extensively that plants are subjected to severe abiotic and biotic stressors. The scientific research community has widely reported that multi-abiotic stressors cause horticultural crop losses, accounting for at least 50 to 70% of the crop yield and quality losses. Therefore, this review focused on the detrimental effects caused by abiotic stress factors occurring in single-, combined- and multi-cell stresses on horticultural plants worldwide, along with the best production systems practices for mitigation during and post-single and combined abiotic or multi-stress damages. A conclusion and recommendation could be reached using the pool of research material, which constituted research articles, reviews, book chapters, thesis, research short communications and industrial short communications from at least twenty-five years ago. Findings showed that some of the leading abiotic stresses are single- and combined abiotic stressors like water deficit, salinity, soil pH, phosphate deficiency, wounding, soil density and pot size. Established commercial and smallholder farmers are globally adapting to plant growth regulators and biostimulants as part of their production systems. However, as much as the effectiveness of biostimulants containing humic acids, algal extracts, plant growth-promoting microorganisms and phytohormones has been reported to promote plant development under multi-stress, only a few studies are focusing on organic phytohormone-based biostimulants on horticultural crops grown under adverse multi stress factoring. In conclusion, the review recommends alternative solutions for emerging South African farmers and growers who cannot afford agricultural insurance options and energy alternatives on the common single

We report the first observation of Argon-40 (Ar-40) in the mid latitude regions (-60 degrees to +60 degrees) of the lunar exosphere from CHandra's Atmospheric Composition Explorer-2 (CHACE-2) experiment aboard Chandrayaan-2 orbiter. The number density of Ar-40 shows pre-sunrise, sunrise and sunset peaks as well as nightside minima, typical of a condensable gas, which is similar to the features seen at the low latitudes in previous observations. The CHACE-2 observed number densities of Ar-40 and its diurnal variation at low latitudes (-30 degrees to +30 degrees) is consistent with LACE/Apollo observations. CHACE-2 observations show Ar-40 enhancements over certain longitude sectors. In addition to KREEP region, Ar-40 bulges are observed at other longitudes, including the South Pole Aitken (SPA) terrain. The global distribution of Ar-40 shows that the sunrise peak is observed at the same local time over highlands and mare regions. These observations call for a deeper understanding of the surface-exosphere interactions and source distribution. Plain Language Summary The Moon is known to possess a tenuous atmosphere, known as surface bound exosphere. Lunar exosphere exists as a result of a dynamic equilibrium between several sources and sink processes. Noble gases serves as important tracers to understand such processes. Though, Argon-40 (Ar-40) is known to exist in lunar exosphere, the knowledge on its distribution at higher latitudes is lacking. For the first time, CHandra's Atmospheric Composition Explorer-2 (CHACE-2) experiment aboard Chandrayaan-2 orbiter has continuously observed Ar-40 in latitude range of -60 degrees to +60 degrees. It is found that the Ar-40 density variation with local solar time shows the behavior of a condensable gas, which is similar to that observed earlier at low latitudes. The distribution of Ar-40 shows spatial heterogeneity with localized enhancements over KREEP and South Pole Aitken terrain. This suggests that there may be other regions with lower activation energy as the source of Ar-40. The observed global distribution indicates that the interaction of Ar-40 with the surface are similar in low and mid latitude regions. The CHACE-2 observations hint at requirement for improvement in our understanding of the surface-exosphere interactions and source distributions of Ar-40. Key Points First observation of Argon-40 in the mid latitude exosphere of the Moon Observed nightside minimum and sunrise and sunset peaks in Ar-40 abundance is similar to that at low latitudes Enhanced Ar-40 number density is observed at few longitudes, including South Pole Aitken terrain, in addition to KREEP

A time-dependent simulation of the argon-40 exosphere of the Moon shows that the semiannual oscillation of argon detected by the neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer spacecraft is consistent with adsorptive respiration in seasonal cold traps near the lunar poles. The magnitude of the oscillation requires that high-energy adsorption sites on soil grain surfaces at polar latitudes be as free of water contamination as soils at low latitudes. This requirement is met by the combination of two generally ignored water removal mechanisms: solar wind bombardment of exposed adsorption sites and the serpentinization reaction of water with olivine. The significance of these processes is supported by the lack of evidence of water in Lunar Atmosphere and Dust Environment Explorer data, which, in turn, establishes an upper bound for exospheric transport of water to polar traps at less than 10(14) molecules/Ga. Plain Language Summary The neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer spacecraft recorded a gradual rise and then fall of atmospheric argon-40 that is consistent with a 140-day segment of a semidraconic oscillation. The semidraconic oscillation of argon is important because its existence has harsh implications for the accumulation of water in polar cold traps. Simulations show that the existence of the oscillation implies respiration of argon atoms in seasonal cold traps near both poles, which in turn requires that polar soil grain surfaces have significant areas of high-energy adsorption sites that are not contaminated by water molecules. The paper argues that such extreme cleanliness can be explained by two previously ignored processes. One is surface scouring by solar wind bombardment of the lunar surface, which leads to escape or scatter to lower latitudes. The other is sequestration of water by the reaction of olivine with water, a process that is known as serpentinization. Coupled with meteoritic gardening, these process are capable of removing water from the lunar atmosphere faster than current estimates of water sources. This conclusion does not preclude the assimilation of water in permanent traps, but it severely reduces the amount of water available for assimilation.

The neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft collected a trove of exospheric data, including a set of high-quality measurements of radiogenic Ar-40 over a period of 142days. Data synthesis studies, using well-established exosphere simulation tools, show that the LADEE argon data are consistent with an exosphere-regolith interaction that is dominated by adsorption and that the desorption process generates the Armand distribution of exit velocities. The synthesis work has uncovered an apparent semiannual oscillation of argon that is consistent with temporal sequestration in the seasonal cold traps created at the poles by the obliquity of the Moon. In addition, the LADEE data provide new insight into the pristine nature of lunar regolith, its spatially varying sorption properties, and the influence of sorption processes on the synodic oscillation of the argon exosphere.

The Neutral Mass Spectrometer (NMS) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) provided the first global characterization of He and Ar along with the discovery of Ne in the lunar exosphere. The mapping of the equatorial distribution of these noble gases revealed new selenographic and temporal variations. Helium was found to be controlled by the supply of solar wind alpha particles and by the presence of an endogenous source that supplies the exosphere at a rate of 1.9x10(23)atomss(-1). Neon was detected over the nightside at levels comparable to He and was found to exhibit the spatial distribution of a surface accommodated noncondensable gas. The global measurements of NMS revealed the presence of a localized Ar enhancement that has never been identified before at the western maria. The variability resulting from this local enhancement is coupled to a more global but transient source.

The Neutral Mass Spectrometer (NMS) of the Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission is designed to measure the composition and variability of the tenuous lunar atmosphere. The NMS complements two other instruments on the LADEE spacecraft designed to secure spectroscopic measurements of lunar composition and in situ measurement of lunar dust over the course of a 100-day mission in order to sample multiple lunation periods. The NMS utilizes a dual ion source designed to measure both surface reactive and inert species and a quadrupole analyzer. The NMS is expected to secure time resolved measurements of helium and argon and determine abundance or upper limits for many other species either sputtered or thermally evolved from the lunar surface.

[1] The common wisdom that water ice may exist in lunar polar cold traps has become a significant factor in the selection of space research objectives. The purpose of this paper is to address two topics that are missing from the discourse on lunar water: the effect that the pristine cleanliness of the regolith has on water transport on the moon, and the limits on water exposure implied by the extremely high adsorption potentials of the surfaces of soil grains. Water transport is characterized by chemisorption on soil grains and the mixing of wet'' grains into the regolith by meteoritic gardening. Ballistic lateral flow, which is generally thought to be an efficient conduit for moving water to the poles, is actually a secondary phenomenon that is facilitated by solar wind and micrometeor erosion but not by thermal desorption, as is the case for the dominant lunar exospheric gases, He and Ar-40. Simulation results show that even under the most optimistic conditions, less than 7% of the water accumulated in the regolith resides in the polar cold traps, where water concentrations cannot be greater than 350 ppm. More important, when realistic transport parameters are used in the simulator, the polar water concentration is reduced by almost 2 orders of magnitude. In a word, the concept of water ice at the lunar poles is insupportable.