Phosphorus Improves Leaf Nutrient Concentrations in Wheat, Oat, and Cereal Rye

Core Ideas: Increased P availability increases leaf P and Mg in wheat, oat, and rye. The grass tetany ratio is improved with greater P availability in these species. Unlike cereal rye and oat, wheat increases shoot growth with high P levels. Winter annual species grown for forage are prone to mineral imbalances that could result in animal nutritional disorders, such as grass tetany. Adequate soil P has been found to be critical for the growth and adequate nutrient content of Mg, Ca, and K in other forages for grazing animals. This study examined the effect of P availability on growth and leaf nutrients in annual cereal grains commonly grown for winter forage. Winter wheat (Triticum aestivum L.), oat (Avena sativa L.), and cereal rye (Secale cereal L.) were grown hydroponically in greenhouse conditions in complete nutrient solutions with P treatments of 0, 200, 400, and 800 µmol L−1 P. After 32 d, plants were harvested and analyzed for P, Mg, Ca, and K content. Shoot growth of all three species increased from 0 to 200 µmol L−1 P; however, only wheat shoots increased incrementally with the other P treatment concentrations. Leaf P also responded incrementally to increased P treatments in all three species. Wheat and cereal rye exhibited increases in leaf Mg and improved grass tetany ratio from 200 to 400 µmol L−1 P, whereas oat showed these improvements from 0 to 200 µmol L−1 P treatments. This study suggests increased P availability could improve the grass tetany ratio, with or without increased shoot growth, in winter annual forage production on low P soils

Effects Of Combinations Of Para-Hydroxybenzoic Acid And Boron On Growth And Mineral Content Of Velvetleaf

Para-hydroxybenzoie acid (pHBA) is frequently implicated in plant to plant biochemical interactions (allelopathy), and it may inhibit growth by disturbing membrane functions. A primary focus of this study was to determine if levels of pHBA near the growth-inhibition threshold will alter mineral content of velvetleaf (Abutilon theophrasti Medic.) tissue. A second objective was to determine if the level of available boron (B) alters possible effects of pHBA on growth and nutrient accumulation in leaf tissue. Velvetleaf seedlings were grown in nutrient solution in a completely randomized factorial design under greenhouse conditions in three separate 3-4 week long trials. Trial 1 had crossed treatments of zero, 250, and 500 uM pHBA and 1, 10, and 50 uM B. Solutions were changed every 3 days. Later trials added 100 uM B treatments, and the growth media was aerated and adjusted to pH 5.5. Trial 1 showed significant main effects of B and pHBA on velvetleaf root, shoot, and leaf dry weights and leaf area with both 1 uM B and 500 uM pHBA suppressing growth. There was also a significant pHBA*B interaction on growth. Subsequent trials showed a significant main effect of B on growth with 1 uM B suppressing growth in pHBA-treated plants. Leaf tissue was analyzed for B, Fe, K, Mg, Mn, and P content using inductively coupled plasma-atomic emission spectrometry and Ca content using atomic absorption spectrophotometry. Compared to 10 uM B controls, leaf B concentrations decreased in 1 uM B tretments and increased in 100 uM B. In 500 uM pHBA, Trial 2 and 3 plants showed elevated levels of K, Mg, Mn and P leaf content. Environmental differences between trials appeared to affect the inhibition threshold of pHBA. This study rendered no conclusive evidence of B treatments altering allelopathic effects of pHBA

Morphological traits underlying differences in early vigor among four cotton genotypes

In comparison with other annual crops, cotton (Gossypium hirsutum L.) seedlings develop slowly after emergence. More rapid seedling development can provide advantages in limiting disease, insect, and weed impacts on cotton seedlings. Information on the mechanisms determining early vigor in cotton is limited. Therefore, three genotypes previously identified to differ in seedling vigor and one commercial cultivar were selected for detailed characterization of early growth in greenhouse and field conditions. Growing environment and genotype effects were significant for many of the measured traits. Environmental conditions prevailing in field and greenhouse conditions differentially affected seedling growth, including cotyledon biomass, root weight ratio (RWR), net assimilation rate (NAR), and specific leaf area (SLA). Genotypic differences were found in one or both environments for cotyledon area, area of the first leaf, total leaf area, and leaf, stem, root, and total biomass. Leaf weight ratio (LWR), stem weight ratio (SWR), RWR, LAR, and SLA differed among genotypes at most stages, but this was not the case for relative growth rate and NAR. The high‐vigor genotype generally had longer roots, larger cotyledons, greater cotyledon, stem, and total biomass, and greater SWR and RWR than the low‐vigor genotype. The low‐vigor genotype had the greatest LAR, SLA, and LWR among the four genotypes. Results obtained in this study suggest that factors such as the efficiency of photoassimilate conversion into biomass, energy density of the biomass, root carbon exudation, and/or photosynthetic rates differ between the low‐vigor and high‐vigor genotypes