Abstract Onion (Allium cepa L.) is an important food bulb crop used for various dishes and medical purposes. However, purple blotch disease limits productivity and production of onion in onion‐growing regions. Thus, this research was conducted to assess the distribution and intensity of purple blotch of onion and determine the associations of disease parameters with biophysical factors. A total of 130 onion fields from four districts in two zones were surveyed during the 2022/23 cropping season to measure disease and biophysical data during the survey periods. The associations of disease parameters and biophysical factors were analyzed using the binary logistic regression model by employing the SAS GENEMODE procedure. The survey results confirmed 100% prevalence of purple blotch. The highest disease incidence and severity were assessed from Gondar Zuria (37.13% and 23.01%) and Libokemkem (36.24% and 21.34%) districts, respectively. High disease incidence (>45%) and severity (>25%) were strongly associated with bulbing and maturity crop growth stages, field size (>0.25 ha), blub previous crop, late October transplanting, more than six times fungicide application, and less than four times land preparation. Lower disease incidence (≤45%) and severity (≤25%) had a strong association with early December transplanting, more than four times land preparation, fungicide spray (≤6 times), field size (≤0.25 ha), and fields previously planted with cereals. Thus, these practices could be considered management options to reduce the impact of the disease in onion‐growing areas in northwestern Ethiopia and other similar areas of the country. Future research on pathogenic variability is required to develop long‐term disease management strategies.

Abstract New technologies have been developed to extract and recover manure nitrogen (N) and phosphorus (P) that can be upcycled as substitutes for conventional fertilizers. Yet, there are uncertainties over the agronomic effectiveness of these recovered nutrients. In a greenhouse study, we evaluated annual ryegrass (Lolium multiflorum Lam.) response to recovered N (RN), conventional N (CN), recovered P (RP), and conventional P (CP) in four nutrient combinations: CN + CP, RN + CP, CN + RP, and RN + RP at five N rates: 0, 23, 46, 92, and 184 mg N kg−1 soil; and three P rates: 0, 39, and 78 mg P kg−1 soil. Results showed a synergistic response to N and P, where dry matter yield and nutrient uptake increased with both nutrients application. Under CP, ryegrass supplied with 92 and 184 mg N kg−1 of CN produced 16%–35% more dry mass yield than RN. In contrast, ryegrass dry mass yield under RP was 17%–114% greater with RN than CN. Ryegrass dry mass yield under CP was 17% greater with CP than RP at 78 mg P kg−1 soil, but RP produced 27%–66% more dry mass yield than CP under RN. There was no difference in soil inorganic N between the two N sources, but Mehlich‐1 soil test P was less in RP than CP treated soil. The combination of RN and RP was an effective fertilizer blend for substituting CN and CP. This finding is critical for the advancement of the new circular nutrient economy.

Abstract There is rising interest in the United States for industrial hemp (Cannabis sativa L.) cultivation as a new cash crop after the recent reversal of its production ban. Due to limited research during its long prohibition, little information is available regarding its optimal cropping system and crop management practices. Hence, the study was conducted to identify the optimal plant spacing for two cannabidiol (CBD)‐dominant industrial hemp cultivars (BaOX and Wife) in Florida. Three plant spacing treatments, that is, 61 cm (24 in.), 91 cm (36 in.), and 122 cm (48 in.), were used with a common row spacing of 1.52 m. Plant height, chlorophyll content using soil plant analysis development 502, and canopy cover using Canopeo were recorded every 2‐weeks interval throughout the crop growing season. The final biomass yield, CBD, and delta‐9‐tetrahydrocannabinol (THC) yield were also recorded. The results showed no significant differences between the cultivars in biomass, CBD yield, and plant growth and physiological parameters in most of the observations. Plant height and chlorophyll content were mostly unaffected by spacing. Canopy cover was higher during most of the growing season at lower spacing. Dry biomass yield per plant was higher with wider spacing, but there was no significant difference in total biomass yield per unit area. Wider spacing (91 and 122 cm) also resulted in higher CBD and THC yield in one of the tested cultivars (BaOX). The results suggest that wider plant spacing in industrial hemp could help maximize CBD production in Florida and other regions with similar environmental conditions.

Abstract Hemp (Cannabis sativa L.) is a dioecious, diploid (2n = 2x = 20), photoperiod‐sensitive crop cultivated worldwide for a variety of uses, including food, feed, medicine, and fiber. Hemp is parsed into different market types, including fiber, grain, dual purpose, and high cannabinoid production. Planting densities for the different market types varies greatly, with fiber production systems planted at a much higher density than those for cannabinoid production. Current recommendations for fiber seeding rates range between 45 and 67 kg per hectare (kg ha−1), with other recommendations reaching 90 kg ha−1. However, few studies have been conducted to determine optimal planting density while considering fiber quality, yield, and input cost. In this study, we used four different planting densities (221 plants m−2, 111 plants m−2, 74 plants m−2 and 55 plants m−2) in a replicated greenhouse trial to study their effect on plant height, stem diameter, and branching. Planting density significantly affected each trait, with a seeding density of 221 plants m−2 producing the thinnest, shortest, and least branched plants. All stem traits were positively correlated with plant height, and stem diameter was the most correlated. A planting density of 111 plants m−2 reduced branching but still produced long, thin stems, translating into a high bast fiber yield while reducing seed input costs and competition between plants.

Abstract Fusarium wilt caused by the fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) is one of the major threats challenging the banana industry in tropics including Ethiopia. Foc infects the xylem, induces wilt, and kills banana plants. Hence, it affects the production and productivity of both commercial and local banana cultivars. In southern Ethiopia where banana is dominantly grown, it is considered as an emerging disease due to its extensive distribution across districts and consequences on the livelihood of the producers. Hence, this study was conducted to evaluate the resistance of commercial banana cultivars against the disease at Arba Minch Agricultural Research Center, Ethiopia. In 2021–2022, an experiment was conducted involving seven commercial banana cultivars in completely randomized design with factorial arrangement with three replications. Pathogenicity tests were conducted by artificially inoculating 6‐month‐old seedlings of white Habesha cultivar obtained from Melkasa Agricultural Research Center and raised in polythene bags. Observations of external leaf symptoms and internal rhizome discoloration were made to determine the responses of the cultivars and evaluated using standard scales of leaf symptom index and rhizome discoloration index. Data on incubation period, disease incidence, and percent severity index were collected and subjected to the analysis of variance using the SAS software version 9.2, and means were compared using least significant difference test (α = 0.01). The result obtained from the responses of the cultivars showed that William 01 and Grand Naine hybrids were categorized as resistant, but Poyo and Ducasse hybrids were categorized as susceptible and highly susceptible, respectively. The analysis also revealed that Butuzua, Giant Cavendish, and Dwarf Cavendish hybrids were found to be tolerant to the disease. In addition, the analysis of variance indicated that incubation period and severity values ranged from 10 to 46 and 13.33% to 63.33%, respectively. Therefore, it is recommended that those susceptible and highly susceptible cultivars should be replaced by the resistant ones to reduce the devastation posed by the disease, and tolerant cultivars could be maintained in production with the implementation of effective integrated disease management practices. It is also suggested that, due to the limitations inherent to banana genetics, breeding disease‐resistant bananas, including the Cavendish dessert banana, represents a middle‐ to long‐term strategy as a future research direction in the study area and other tropical countries where the pathogen is the most prevalent.

Abstract Unmanned aerial vehicles (UAVs) equipped with cameras are used for collecting vegetation indices (VIs) for health monitoring of field crops such as rice (Oryza sativa). This study evaluated the relationship of VIs derived from multispectral UAV images at different buffer zones around the sampling points with rice biomass and grain yield from 20 nonirrigated and irrigated fields in Sakhon Nakhon, Thailand, in 2021. Varying nitrogen (N) rates (21.8–98.7 kg ha−1) were applied in splits, at 14 days after transplanting and panicle initiation (PI) stage. One week after PI, multispectral images were captured by a DJI Phantom 4 Multispectral UAV before taking biomass samples at four 1‐m2 sampling points for the three plots in each field. At harvest, whole plant samples were collected from nearby these sampling points for grain yield estimation. For each sampling point at buffer zones 5, 10, and 20 m, the average of four VIs (normalized difference vegetation index [NDVI], green NDVI [GNDVI], normalized difference red‐edge [NDRE], and optimized soil adjusted vegetation index [OSAVI]) was computed. Correlation analysis showed NDRE had the highest correlation with grain yield in nonirrigated systems (r = 0.575–0.613) and pooled data (r = 0.523–0.539). NDVI moderately correlated with biomass (r = 0.224–0.233). Images within the 10‐m buffer zone produced NDRE values most strongly linked to yield, both unadjusted and normalized by planting to sensing days and growing degree days. There is a potential to use NDRE as predictor of rice biomass yield in rice systems.

Abstract Low soil fertility, inappropriate fertilizer application, and low input use are prominent factors contributing to low agricultural productivity in Ethiopia, where soil fertility status varies significantly across the landscape. Applying the correct rate, type, timing, and placement of fertilizers is essential for maximizing agricultural benefits and ensuring sustainable productivity. Addressing these issues is critical for promoting sustainable agricultural practices and improving food security. Therefore, the objective of the experiment was to identify the major yield‐limiting soil nutrients for sorghum yield in northern Ethiopia. A randomized complete block design with three replications was used at each landscape positions. The nutrients evaluated in the study were nitrogen (N), phosphorus (P), sulfur (S), zinc (Zn), boron (B), and potassium (K). The treatment applied included control, recommended NP (RNP), NPSZnB, NPKSZnB, NPZnB, NPSB, NPSZn, 150% NPKSZnB, and 50% NPKSZnB. These treatments were implemented across each landscape position. The research findings indicated that the application of 150% All + K nutrients resulted in the highest grain and biomass yields across all landscape positions. When compared with the RNP treatment, there was no significant difference in yield at all slopes. Omitting S, Zn, B, and K did not significantly affect the grain and biomass yields, suggesting that these nutrients are not yield limiting for sorghum in the study area. These findings suggest that prioritizing N‐ and P‐containing nutrients is essential for maximizing sorghum yield, thus contributing to sustainable agricultural practices and improved food security in the region.

Abstract Phosphorus (P) is one of the three most limiting essential nutrients for crop growth and yield. However, information on the optimum P application rate for production of industrial hemp (Cannabis sativa L.) is very limited, especially in Florida. The objective of this study was to determine the impact of various P application rates on growth and yield parameters of industrial hemp in two sites in Florida (Central FL and Northwest FL). The experimental design was a randomized complete block with four replications. Treatments consisted of five P rates—0, 34, 67, 101, and 135 kg P ha−1. Data were collected on plant stand count and plant height at 15, 30, and 50 days after planting, while data for aboveground biomass were collected at harvest in both locations. Additionally, stem biomass in Northwest FL site and seed yield in Central FL site were collected. There was no significant effect of different P rates on plant height, plant stand count, and aboveground biomass in either location (p ≥ 0.05). Also, the P rate effect was nonsignificant for stem biomass (p = 0.512) in Northwest FL site and seed yield (p = 0.250) in Central FL site. The 135 kg P ha−1 yielded numerically higher ground biomass in Central FL site (2200 kg ha−1) while 100 kg P ha−1 was higher in Northwest FL site (9432 kg ha−1). Similarly, 135 kg P ha−1 yielded numerically higher stem biomass (6000 kg ha−1) in Northwest FL site and seed yield (900 kg ha−1) in Central FL site. Thereby, the results suggest that P fertilization has a limited effect on biomass and seed yields for industrial hemp production in Florida sandy soils.

Abstract Cannabis sativa L. (marijuana, hemp) is one of the few dioecious angiosperm species with sex chromosomes. Along with other closely related genera from the family Cannabaceae, C. sativa exhibits monoecious (unisexual flowers at different locations within the individual) and dioecious (two sexes in separate individuals) populations. Despite recent progress in understanding the plant's biology, its sexual strategies are still not fully understood and key advancements such as complete genome assemblies that include the Y and monoecious chromosomes are still lacking. Here, we summarize the diverse reproductive strategies within angiosperms focusing on the family Cannabaceae—with members that have varying sex chromosome number—and specifically on C. sativa. We include the characterization of the non‐recombining and pseudoautosomal regions of the Y chromosome, the different size estimates of the sex chromosomes, and the multiple genetic markers that have been developed for sex determination in C. sativa. We then describe the genetic and environmental factors influencing sex expression in C. sativa, with external factors presenting practical applications in agriculture systems such as the production of “feminized seeds” through sex reversal techniques. Additionally, important agricultural characteristics between males, females, and monoecious plants emphasize the importance of sex determination for fiber quality and medicinal applications. This comprehensive overview of sex determination in C. sativa contributes significantly to the understanding of this complex and economically important plant, offering valuable insights for researchers and cultivators in this nascent industry.