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Cannabis sativa is cultivated for multiple uses including the production of cannabinoids. In developing improved production systems for high‐cannabinoid cultivars, scientists and cultivators must consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Determining factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids. Thirty‐two high‐cannabinoid hemp cultivars were characterized for traits including flowering date and shoot‐tip cannabinoid concentration. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post‐harvest to quantify intra‐plant variation in inflorescence biomass production and cannabinoid concentration. Some cultivars showed intra‐plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra‐ and inter‐cultivar variation in architecture that correlated with intra‐plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from various positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders. [ABSTRACT FROM AUTHOR]

Persistence is a critical trait for alfalfa (Medicago sativa L.), yet the genetics of this trait are poorly understood. Herein, we characterize an [F.sub.1] alfalfa population derived from the cross between the two cultivated alfalfa subpecies for persistence in three production seasons at Ames and Nashua, IA, and one production season at Ithaca, NY. Quantitative trait loci (QTLs) underlying persistence were mapped using this population utilizing single-marker analysis and interval mapping procedures. Both parental genomes (Medicago sativa subsp, falcata and M. sativa subsp, sativa) contributed marker alleles associated with persistence, suggesting that alleles from both subspecies have potential for marker-assisted selection. Although, linkage groups 1, 2, and 7 contained putative persistence QTLs, genotype x environment interaction and location-specific QTLs suggest location-specific genetic mechanisms for alfalfa persistence. Nevertheless, in some instances, the same QTLs were identified in different years at the same location. Quantitative trait loci on linkage groups (LGs) 1 and 2 were location-specific for the Ithaca and Ames locations, respectively. The majority of alleles on LG 7 associated with persistence also exhibited association with biomass production and suggest common genetic determinants for both traits. Of particular interest was the identification of simple sequence repeat allele al37288-1a1, which associated positively with persistence in each environment of the study.

Biomass production represents a fundamental biological process of both ecological and agricultural significance. The genetic basis of biomass production is unknown but asssumed to be complex. We developed a full sib, [F.sub.1] mapping population of autotetraploid Medicago sativa (alfalfa) derived from an intersubspecific cross that was known to produce heterosis for biomass production. We evaluated the population for biomass production over several years at three locations (Ames, IA, Nashua, IA, and Ithaca, NY) and concurrently developed a genetic linkage map using restriction fragment length polymorphism (RFLP) and simple sequence repeat (SSR) molecular markers. Transgressive segregants, many of which exhibited high levels of heterosis, were identified in each environment. Despite the complexities of mapping within autotetraploid populations, single-marker analysis of vailance identified 41 marker alleles, many on linkage groups 5 and 7, associated with biomass production in at least one of the sampling periods. Seven alleles were associated with biomass production in more than one of the sampling periods. Favorable alleles were contributed by both parents, one of which is from the M. sativa subsp. falcata germplasm. Thus, increased biomass production alleles can be gleaned from unadapted germplasm. Further, the positive quantitative trait locus (QTL) alleles from the parents are partially complementary, suggesting these loci may play a role in biomass production heterosis.

Genetic improvement of alfalfa (Medicago sativa L.) for increased pectin concentration, estimated by neutral detergent soluble fiber (NDSF), would improve the efficiency of utilization of its high protein and digestibility by ruminants. The objectives of this study were to: (i) estimate the realized direct response from one cycle of phenotypic selection for NDSF concentration; (ii) evaluate association of NDSF concentration with other forage quality traits, and; (iii) determine the impact of selection for NDSF concentration on in vitro dry matter digestibility (IVDMD) of alfalfa. Selection for NDSF was applied to five alfalfa populations from 1996 to 2000 and synthetic generation two seed was produced. Progress from selection for NDSF concentration was evaluated in plot trials for 2 or 3 yr at two locations near Ithaca, NY. Populations divergently selected for NDSF were 1.62 to 5.15 g [kg.sup.-1] of dry matter (DM) higher and 2.26 to 4.20 g [kg.sup.-1] DM lower, respectively, than their respective base populations. Neutral detergent soluble fiber concentration was negatively correlated with total cell wall concentration (CW), and proportions of neutral detergent fiber (NDF), cellulose, and lignin in the CW. A positive correlation existed between NDSF concentration and crude protein (CP) concentration and IVDMD. Populations bred for higher or lower NDSF concentration had 0.20 to 8.82 g [kg.sup.-1] DM higher IVDMD and 0.63 to 15.06 g [kg.sup.-1] DM lower IVDMD than their respective base populations. Selection for NDSF concentration and indirectly for CP, total CW concentration and composition, and IVDMD of alfalfa forage was successful., ALFALFA is the predominant forage source of protein for dairy cattle in temperate regions. High levels of soluble protein typically present in alfalfa exceed the capacity of rumen microbes to [...]

During wilting of alfalfa (Medicago sativa L.) before preservation as silage or hay, proteinases in plant cells hydrolyze soluble protein (SP) into nonprotein N (peptides and amino acids), thus decreasing postharvest quality of alfalfa. Our objectives were to compare (i) expected gain in SP concentration remaining in wilted, lyophilized alfalfa from direct selection with expected and actual gain from indirect selection for N concentration and (ii) phenotypic selection with half-sib (HS) progeny test for gain in both SP and N concentrations in wilted, lyophilized forage. In Exp. 1, heritabilities for SP and N concentrations in wilted, lyophilized alfalfa were estimated by parent-offspring regression and by HS progeny analysis. Samples of alfalfa forage from HS families and individual plants were wilted for 24 h, chopped, frozen, and lyophilized. Near-infrared reflectance spectroscopy (NIRS) was used to predict SP and N concentrations in samples. Heritability estimates for N concentration were moderate in magnitude (0.29 to 0.76), and those for SP concentration were low (-0.03 to 0.46). The expected gain in SP concentration was higher from selection for N concentration than from direct selection. In Exp. 2, two alfalfa populations previously selected for higher N concentration and two unselected cultivars were grown in sward plots. Unwilted forage had 25% (P is less than or equal to 0.01) higher SP concentration in 1987 than forage that had been wilted for 24 h and had 13% (P

Hemp ( Cannabis sativa <0.3% tetrahydrocannabinol) is an emerging crop used for grain, fiber, and cannabinoid production (Fike et al. 2020). In New York, hemp is grown both in controlled environment facilities, including greenhouses, and as a field crop. In August 2020, downy mildew-like symptoms were observed on leaves and inflorescence of hemp plants in a field research trial in Ithaca, NY. Several cultivars, including 'Auto CBD', were affected. Disease was severe with some plants reaching 75% disease severity at the individual plant level. In the most severely affected plots, there was no marketable yield. The disease was characterized by chlorotic and necrotic lesions producing sporangiophores under high humidity. Pigmented sporangia were produced on branched sporangiophores. On artificially inoculated leaves incubated at 18°C, 80% humidity, 12h light for 5d, sporangiophores produced 8-19 pigmented, lemon-shaped sporangia with mean ± SD dimensions of 25.2 ± 3.0 (18.9 to 30.4) x 18.2 ± 2.1 (14.6 to 23.2) µm (n=50). Each sporangium produced 2-5 zoospores after less than 45 min in water at room temperature (22°C). Sporangia were collected from sporulating lesions and DNA was extracted as outlined in Crowell et al. (2020). Fragments of the ribosomal internal transcribed spacer (ITS) region (White et al. 1990), the beta-tubulin ras-associated ypt1 gene (Moorman et al. 2002), and the mitochondrial cytochrome B oxidase subunit 2 ( cox2 ) gene (Hudspeth et al. 2000) were amplified by PCR and sequenced bidirectionally. Sequences were deposited in GenBank under accession numbers OK086084, OM867581, and OM867580, respectively. BLAST searches using the amplified ITS and cox2 sequences resulted in 100% identity to Pseudoperonospora cannabina (HM636051.1, HM636003.1) with ypt1 aligning at 97.95% identity (382/390 bp) with P. cannabina (KJ651402.1). The molecular characterization identified the causal agent as P. cannabina . A representative isolate was deposited in the Cornell Plant Pathology Herbarium as CUP-070922. Sporangia were rinsed from detached leaves and used to confirm pathogenicity on whole plants. Ten 4-week-old 'Anka' plants were spray-inoculated until run off with a suspension of 1x10 4 sporangia mL -1 . Ten control plants were sprayed with water. After inoculation, plants were placed in a 19˚C growth chamber with a 12-h photoperiod and misted for 30 min twice daily to maintain humidity above 80%. Sporangia and previously described symptoms were observed 7 days post-inoculation, while control plants were asymptomatic. The pathogen was reisolated onto detached leaves of 'Anka' from inoculated leaves where both sporangia and oospores were observed. The reisolated pathogen was confirmed morphologically and molecularly, through PCR amplification and bidirectional sequencing of the ITS, cox2 , and ypt1 genes, as P. cannabina . To our knowledge, this is the first report of P. cannabina causing hemp downy mildew in New York. Depending on the severity and timing of infections, this disease could pose a significant threat to hemp production in the state. Other members of the genus, P. cubensis and P. humuli cause downy mildew on cucurbits and hops, respectively. As these can cause devastating diseases on their hosts, P. cannabina must be monitored with vigilance as an emerging pathogen (Purayannur et al. 2021; Savory et al. 2011). Literature Cited: Crowell, C. R., et al.2020. Plant Dis. 104:2949. DOI 10.1094/PDIS-04-20-0718-RE Fike, J. H., et al. 2020. Page 89 In: Sustainable Agriculture Reviews, vol 42. Springer, Cham, Switzerland. DOI 10.1007/978-3-030-41384-2&#95;3 Hudspeth, D. S. S., et al. 2000. Mycologia 92:674. DOI 10.2307/3761425 Moorman, G. W., et al. 2002. Plant Dis. 86:1227. DOI 10.1094/PDIS.2002.86.11.1227 Purayannur, S., et al. 2021. Mol. Plant Pathol. 22:755. DOI 10.1111/mpp.13063 Savory, E. A., et al. 2011. Mol. Plant Pathol. 12:217. DOI 10.1111/j.1364-3703.2010.00670.x White, T. J., et al. 1990. Page 315 In: PCR Protocols. A Guide to Methods and Applications. Academic Press, San Diego, CA. DOI 10.1016/B978-0-12-372180-8.50042-1.