Hemp (Cannabis sativa L. ssp. sativa) has a long history of domestication due to its versatile use. Recently, different sectors in the economy are investigating hemp cultivation to increase agronomic production and to limit delta-9-tetrahydrocannabinol (THC). Despite the rapid growth of hemp literature in recent years, it is still uncertain whether the knowledge gained from higher latitude regions is applicable to low latitude and tropical regions where hemp has not been grown traditionally. This review provides a comprehensive and updated survey of hemp agronomy, focusing on environmental and management factors influencing the growth and yield of hemp, methods of cannabinoids detection and quantification, and hemp breeding. This review suggests that some previous claims about hemp as a low input crop may not hold true in low-latitude regions. Additional research strategies, such as the integration of experimentation and modeling efforts, are encouraged to hasten new discoveries. Furthermore, to effectively increase the outputs of value products (cannabinoids, seeds, fiber and biomass, etc.) while limiting the THC level, new collaborations between hemp agronomists and economists may streamline the production process by increasing the efficiency of the total production system of hemp as a multifaceted crop.

For guar, a well-known drought and heat-tolerant industrial legume with a spring–summer cycle, limited research has been conducted into measuring the effects of drought on yield potential. A two-year field experiment was conducted to explore the effects of different irrigation regimes on yield, yield components and water use efficiency (WUE) on five cultivars of guar (Kinman, Lewis, Matador, Monument, and Santa Cruz) in a semi-arid Mediterranean environment. Three different water replenishment levels were used: fully irrigated (I_H, 100% of the ET), and 50% (I_M) and 25% (I_L) irrigated. Seed yields ranged from 1.24 (I_L) to 3.28 t ha⁻¹ (I_H) in 2011, and from 0.98 (I_L) to 2.88 t ha⁻¹ (I_H) in 2012. Compared to I_H, the two-year average seed yield reductions for I_L and I_M were 49% and 26%, respectively. Lewis and Santa Cruz showed significantly greater grain yields under fully-watered and water-limited conditions. The number of pods per plant achieved the highest positive direct effects on seed yield (r = 0.924***). The highest values of water use efficiency were observed in the I_L water regime (1.44 kg m⁻³ with increments in improved water use efficiency of +34 and +95% when compared with I_M and I_H, respectively).

Deviation from uniform target plant population density in sunflower (Helianthus annuus L.) production may negatively affect canopy closure, yield, and grain quality. The objective of this study was to evaluate the effects of plant density heterogeneity on yield, quality, and canopy closure in confectionery and oilseed sunflowers. Field experiments consisted of fixed differences in the number of skips/doubles per plot while maintaining equal total number of plants, and stand gaps with proportional decreasing plant counts. These were conducted in Minnesota, Texas, and Colorado, USA. Experiments revealed that yield was occasionally influenced by heterogeneity, with more uniform stand density yielding higher; however, substantial changes in uniformity of plant density often resulted in no differences in yield. Confectionery sunflowers compensated for yield losses in thinner stands mainly by producing larger seeds (observed range of 0.1%–46.2% of seeds over a 9.53 mm sieve), while oilseed sunflowers increased seed production per head (as shown by invariable test weight across treatments within environments). Plants that were unharvestable for any cause (most often due to head rot disease or lodging) were more prevalent in less uniform stands, and faster canopy closure was achieved in uniformly spaced plants. Although sunflower is very resilient to stand uniformity issues, these findings underscore the importance of uniform sunflower plant spacing for effective weed suppression and crop performance and highlight the need for further research into sunflower yield compensation mechanisms.

Industrial hemp is receiving attention for its numerous benefits, particularly in the fiber industry. Weed competition is a primary concern for hemp cultivation, causing reduced yields and inferior‐quality fiber. However, little is known about herbicide application in hemp since a limited range of herbicides are available for hemp production. During 2023, this study evaluated the effect of different post‐emergence herbicides applied at early and late growth stages to optimize weed suppression and minimize crop injury in hemp under semiarid conditions. A randomized complete block design was used with six herbicide treatments, including early post (2 weeks after planting [WAP]) and late post (5 WAP) emergence applications of S ‐metolachlor, clopyralid, and ethalfluralin. Hemp plant stand showed no significant difference among treatments. Early post herbicide application reduced 86% of weed biomass compared to untreated control at 7 WAP. By 10 WAP, weed biomass became comparable across treatments. At harvest, untreated control recorded comparatively higher weed biomass than early post treatments and late post ethalfluralin. Plant height remained nonsignificant among treatments until 10 WAP. At harvest, control showed no variation with late post treatments but recorded an average of 63% lower plant height than early post applications. Hemp biomass was insignificantly affected by treatments at 10 WAP. However, on average, early post S ‐metolachlor and ethalfluralin applications demonstrated potential as effective herbicides, yielding four‐folds greater hemp biomass than untreated control at harvest. In conclusion, early post S ‐metolachlor and ethalfluralin are promising tools for weed control, enhancing crop competitiveness and yield in hemp cultivation.

Intercropping rhizobia‐inoculated forage legumes in organic wheat systems reduces weed pressure and supplies nitrogen (N) to the companion crop via biological N ₂ fixation (BNF). However, adoption of combined intercropping and rhizobial inoculation remains limited. This 2‐year field study compared durum wheat ( Triticum turgidum L. subsp. durum (Desf.) Husn.), as a sole crop, or intercropped with forage legume ( Trifolium subterraneum L., Trifolium michelianum Savi, or Vicia sativa L.) in southern Italy. Legumes were rhizobia‐inoculated or non‐inoculated. Treatments were evaluated under reduced N fertilization (60 kg N ha ⁻¹ ) or standard N fertilization (120 kg N ha ⁻¹ ). The warmer and drier 2023/2024 season reduced wheat yields but increased grain protein, whereas the wetter 2024/2025 season enhanced yields, BNF (estimated using published empirical relationships linking N ₂ fixation to legume biomass yield and shoot N content), and wheat N recovery efficiency. Regardless of environmental conditions or agronomic treatments, wheat–legume systems consistently reduced weed biomass compared with sole wheat. Inoculated V. sativa and T . subterraneum improved wheat grain yield versus sole wheat, particularly under favorable conditions at reduced N rate. Vicia sativa exhibited the highest BNF, especially when inoculated at the low N rate, whereas T. michelianum showed smaller benefits. Inoculated T . subterraneum showed the highest nodule number and weight, and higher soil nitrate nitrogen (NO ₃ ⁻ ‐N), particularly at the higher N rate. Although results were context‐dependent on environmental conditions, legume living mulches integrated with effective rhizobial inoculation and reduced N fertilization support the agronomic sustainability of organic wheat systems in Mediterranean environments.