The goal of this research was to investigate the effect of electrical conductivity (EC) levels of the nutrient solution on the fresh weight, chlorophyll, and nitrate content of hydroponic-system-grown lettuce. The selected cultivars are the most representative commercial varieties grown for European markets. Seven cultivars (‘Sintia,’ ‘Limeira,’ ‘Corentine,’ ‘Cencibel,’ ‘Kiber,’ ‘Attiraï,’ and ‘Rouxaï’) of three Lactuca sativa L. types’ (butterhead, loose leaf, and oak leaf) were grown in a phytotron in rockwool, meanwhile the EC level of the nutrient solutions were different: normal (<1.3 dS/m) and high (10 dS/m). The plants in the saline condition had a lower yield but elevated chlorophyll content and nitrate level, although the ‘Limeira’ and ‘Cencibel’ cultivars had reduced nitrate levels. The results and the special characteristic of the lollo-type cultivars showed that the nitrate level could be very different due to salinity (‘Limeira’ had the lowest (684 µg/g fresh weight (FW)) and ‘Cencibel’ had the highest (4396 µg/g FW)). There was a moderately strong negative correlation (−0.542) in the reverse ratio among the chlorophyll and nitrate contents in plants treated with a normal EC value, while this relationship was not shown in the saline condition. Under the saline condition, cultivars acted differently, and all examined cultivars stayed under the permitted total nitrate level (5000 µg/g FW).

Soybean [Glycine max (L.) Merr.] breeding involves crossing and inbreeding for multiple generations to develop genetically stable lines. The long generation times cause early generations to be the major bottleneck in soybean breeding. Here we tested the effect of red and blue light (RB) and full-spectrum white light (FS), coupled with 12-h light (29˚C) vs. 12-h darkness (27˚C) photothermal conditions, on the growth and development of soybean lines and breeding materials of diverse maturity groups (MGs) in a context of speed breeding. We observed that RB light vs. FS light reduced plant height but did not affect vegetative biomass, pods and seeds per plants, nor the ability to meet a minimum of one seed per plant. Overall, the RB treatment reduced the interval planting to physiological maturity by 1.5 d vs. the FS treatment. The period between planting and harvest of mid-and late-maturity soybean ranged from 63 to 81 d, vs. ∼120 d observed in field conditions. Also, days after planting (DAP) to R7 was dependent on soybean MG. The use of RB light, coupled with photothermal conditions herein reported, would allow to advance up to five generations of U.S.-adapted soybean under a controlled environment instead of the one to three generations currently possible. This methodology is simple and easily scalable, for it maintains stable growing conditions throughout the crop cycle and it allows for simultaneous planting and harvesting within the same growth room. This could have a significant impact in genetic gain of U.S. soybean breeding programs.

No abstract

Soybean production in the U.S. Mid-South relies heavily on irrigation with 85% of soybean surfaces irrigated in Arkansas. Reduction in irrigation due to water quantity restrictions will significantly affect soybean seed yield, making variety selection increasingly important. The objective of the study was to assess if irrigation onsets at different reproductive stages affect wilting, seed yield, and key agronomic traits on determinate maturity group 5 (MG 5) soybean. One-hundred sixty-five F4-derived populations of recombinant inbred lines with determinate growth habit, similar maturity, and contrasting wilting potential were planted in an augmented strip-plot design in four environments as a single replicate. Four irrigation onsets were applied at R1 (initiation flower), R2 (full bloom), R3 (initiation pod), and R4 (full pod) using an atmometer. Results indicated significant differences in wilting and yield but no significant differences in maturity, protein, oil concentration, and 100-seed weight across different irrigation onsets. There was no significant difference between the fast and slow wilting genotypes across different irrigation onsets for each trait. Allowable depletions measured in this study indicated that both fast and slow wilting soybean genotype determinate MG5 can tolerate high allowable depletion with no significant yield penalty at R3 growth stage in silt loam soil.

No abstract

R14‐1422 (Reg. no. GP‐523, PI 702562) is a mid‐maturity group (MG) V (relative maturity 5.4), determinate growth habit, high‐yielding, conventional soybean [Glycine max (L.) Merr.] germplasm line developed and released in 2021 by the Arkansas Agricultural Experiment Station. R14‐1422 is an F4 selection from the cross between ‘R06‐4433’, a cultivar released by Arkansas, and the Missouri cultivar ‘S05‐11482’. Trial results of over 74 environments in Arkansas and other southern states showed that R14‐1422 is well adapted and provides high‐yielding performance. R14‐1422 is a MG V (5.4), line with determinate growth habit, white flowers, gray pubescence, and a tan pod wall at maturity. Seed of R14‐1422 has yellow cotyledon, yellow seed coat, and buff hilum color. R14‐1422 has high yield potential and moderate resistance to southern root‐knot nematode and is a chloride excluder.