NO3 −/NH4 + ratios affect plant growth, chlorophyll content, respiration rate, and morphological structure in Malus hupehensis seedlings

Abstract

Malus hupehensis (Pamp.) Rehd. is a widely cultivated rootstock in China. We studied the effect of three NO 3 -/NH 4 ? ratios (100/0, 50/50, and 0/100, molar basis) at total nitrogen (N) concentration of 8 mmoL L -1 in a nutrient solution on M. hupehensis seedlings. Plant biomass, NO 3 -and NH 4 ? concentration, chlorophyll content, respiratory rate, and cellular structure were investigated. M. hupehensis seedlings at the NO 3 -/NH 4 ? ratio of 50/50 had the highest level of fresh weight, dry weight, shoot length, and chlorophyll (a, b, and a ? b) content, but the lowest respiration rate in the leaves and roots. In addition, thickness and numbers of palisade and spongy tissue cells of the leaves were greater with this treatment than with other treatments. At the NO 3 -/NH 4 ? ratio of 100/0, the leaves and roots had higher NO 3 -concentration and lower NH 4 ? concentration. However, the opposite trend occurred at the NO 3 -/NH 4 ? ratio of 0/100. Chlorophyll (a, b, and a ? b) content was lowest at the NO 3 -/ NH 4 ? ratio of 100/0 than at the other ratios. At the NO 3 -/ NH 4 ? ratio of 0/100, oxygen (O 2 ) consumption increased in the leaves and roots, and irregular epidermis and cortex cells were observed in the root apical meristematic and mature region. Our results indicated that the NO 3 -/NH 4 ? ratio at 50/50 was suitable for growth of M. hupehensis seedling to achieve the highest biomass production and efficiency.

Cooperative effects of slight acidic electrolyzed water combined with calcium sources on tissue calcium content, quality attributes, and bioactive compounds of 'Jiancui' jujube

“…Semi‐thin (1.5 μm thickness) and ultra‐thin (70 nm) sections were prepared from these samples using an ultramicrotome (Leica Ultracut R; Leica Microsystems Inc., Wetzlar, Germany). Semi‐thin sections were stained with 10 g L −1 methylene blue including 10 g L −1 sodium borax for 1 min . After washing with deionized water, sections were photographed in a microscope (DMWB3‐223ASC; Motic in North America, Richmond, BC, Canada) with a 1/3″ CCD digital and analog camera under the transmission light (100× magnification).…”