Factors Affecting Leaf Area Development in Husk Leaf of Flint Corn

Abstract

Some corn (Zea mays L.) genotypes produce husk leaves (laminae extending from the husk) that on a per unit area basis, contribute more photosynthate to grain production than culm leaves. Furthermore, a high correlation between husk leaf area and dry weight has been observed, but little is known about the changes in cell components during development of husk leaves. A field experiment was conducted to quantify methanol (MeOH)‐soluble fraction (cytosol) and incorporation of 13C‐labeled photosynthate in cell walls from 9 d before silking (DBS) to silking. The ear leaf of flint corn (F1 of N‐19 by X‐15) was subjected to 13CO2 eight DBS. Leaf area, dry weight, and photosynthetic activity of the husk leaves, and sugar content of various cell components were measured continuously during the 9‐d period. The husk leaf attained one‐half of its maximum apparent photosynthetic rate (Po) when it had 8% of its maximum leaf area at 4 DBS. At 9 DBS, neutral sugars in the MeOH‐soluble fraction accounted for most of nonstarch carbohydrates within the husk leaf (68%), while hemicellulose and cellulose fractions accounted for <10%. At silking, however, sugars in the hemicellulose and cellulose fractions increased by 23 and 56%, respectively. Results of 13CO2 labeling suggest that during rapid husk leaf development, MeOH‐soluble fraction decreases, while the hemicellulose fraction fluctuates, and cellulose fraction increases.

High temperature effects on photosynthate partitioning and sugar metabolism during ear expansion in maize (Zea mays L.) genotypes

“…Such depression in cob (sink) activity might have resulted in the accumulation of methanol soluble sugar concentration in the shank. It is also possible that high temperature promoted expansion of husk leaf and closer proximity of the leaf to the sink improved translocation efficiency and sugar concentration of the shank [13,15,34,35]. Our study further revealed that impairment of sink activity of cob by high temperature may not be consequential to an inadequate supply of assimilates.…”

“…During the presilking period of corn, vegetative parts such as leaves, roots and culm and reproductive organs like ear initiate and grow simultaneously [35]. Simultaneous growth incurs competition for assimilates among the organs and the competition is exacerbated when inclement temperature conditions limit assimilate production by disturbing source activity.…”

“…The husk leaf area expands in parallel with increases in the amount of cell-wall components such as the hemicellulose and cellulose components [15]. In flint corn, the production of cell-wall components such as hemicellulose and cellulose may be related to husk leaf expansion [35]. Therefore, the expansion of the cob may also be associated with the synthesis of cell-wall components.…”

Genome-wide association study (GWAS) reveals the genetic architecture of four husk traits in maize

“…The husk leaf area is positively correlated with the amount of cell-wall components such as the hemicellulose and cellulose fractions [6]. The husk area of flint corn genotypes expands fast with greater capability to synthesize xylose and arabinose, leading to the synthesis of hemicellulose [7].…”