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Lodging Resistance of Japonica Rice (Oryza Sativa L.): Morphological and Anatomical Traits due to top-Dressing Nitrogen Application Rates.

Zhang W, Wu L, Wu X, Ding Y, Li G, Li J, Weng F, Liu Z, Tang S, Ding C, Wang S - Rice (N Y) (2016)

Bottom Line: The plant height, inner diameter of the minor axis (a2) and b2 increased significantly, but the area of the large vascular bundle (ALVB) and the area of the small vascular bundle (ASVB) decreased significantly and resulted in lower stem strength and a higher lodging index under higher top-dressing N conditions.Moreover, the ALVB and the ASVB decreased significantly, while the area of air chambers (AAC) increased rapidly.Top-dressing N application increased the plant height and inner culm diameter and decreased the ALVB and the ASVB of the Wuyunjing23 cultivar and caused deficient lignified sclerenchyma cells, lowered the ALVB and the ASVB, and increased the AAC of the W3668 cultivar resulting in weaker stem strength and a higher lodging index.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Collaborative Innovation Center for Modern Crop Production/National Engineering and Technology Center for Information Agriculture/ Key Laboratory of Crop Physiology and Ecology in Southern China, Nanjing Agricultural University, Nanjing, 210095, China.

ABSTRACT

Background: Lodging in rice production often limits grain yield and quality by breaking or bending stems. Excessive nitrogen (N) fertilizer rates are the cause of poor lodging resistance in rice, but little is known about the effect of top-dressing N application rates on the mechanical strength of japonica rice plants, especially how the anatomical structure in culms is affected by N. In this study, field experiments on two japonica rice varieties with three top-dressing N application rates, 0 kg N ha(-1) (LN), 135 kg N ha(-1) (MN), and 270 kg N ha(-1) (HN) as urea, were conducted. Wuyunjing23, a lodging-resistant japonica rice cultivar and W3668, a lodging-susceptible japonica rice cultivar were used. The lodging index, breaking strength, morphological and anatomical traits in culms were measured in this study.

Results: The visual lodging rate in japonica rice differed remarkably between genotypes and top-dressing N treatments. The higher lodging index of rice plants was primarily attributed to the weak breaking strength of the lower internodes. The longer elongated basal internodes were responsible for higher plant height and a higher lodging index. Correlation analysis showed that breaking strength was significantly and positively correlated with the thickness of the mechanical tissue but was significantly and negatively correlated with the inner diameter of the major axis (b2). With increasing top-dressing N rates, the sclerenchyma cells of the mechanical tissues and the vascular bundles of the Wuyunjing23 cultivar varied little. The plant height, inner diameter of the minor axis (a2) and b2 increased significantly, but the area of the large vascular bundle (ALVB) and the area of the small vascular bundle (ASVB) decreased significantly and resulted in lower stem strength and a higher lodging index under higher top-dressing N conditions. The culm diameter of the W3668 cultivar increased slightly with no significant difference, and the sclerenchyma cells in the mechanical tissues and vascular bundles showed deficient lignifications under high top-dressing N conditions. Moreover, the ALVB and the ASVB decreased significantly, while the area of air chambers (AAC) increased rapidly.

Conclusions: An improvement in the lodging resistance of japonica rice plants could be achieved by reducing the length of the lower internodes, decreasing the inner culm diameter and developing a thicker mechanical tissue. Top-dressing N application increased the plant height and inner culm diameter and decreased the ALVB and the ASVB of the Wuyunjing23 cultivar and caused deficient lignified sclerenchyma cells, lowered the ALVB and the ASVB, and increased the AAC of the W3668 cultivar resulting in weaker stem strength and a higher lodging index.

No MeSH data available.


Related in: MedlinePlus

The thickness of the mechanical tissue of the N4 internodes culm in two japonica rice cultivars under different nitrogen rates. Different lowercase letters represent significant differences (P < 0.05) relative to the LN treatments for Wuyunjing23 and W3668, respectively
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Fig4: The thickness of the mechanical tissue of the N4 internodes culm in two japonica rice cultivars under different nitrogen rates. Different lowercase letters represent significant differences (P < 0.05) relative to the LN treatments for Wuyunjing23 and W3668, respectively

Mentions: In the current study, the mechanical tissue and vascular bundle sheaths of the Wuyunjing23 cultivar were well-developed, whereas many hollow sclerenchyma cells were observed in the W3668 cultivar (Fig. 3). Top-dressing N rapidly altered the minute structures in the two japonica rice cultivars. For instance, with increasing top-dressing N application rates, the thickness of the mechanical tissue was remarkably reduced by 24.0 and 20.7 % in the Wuyunjing23 and W3668 cultivars, respectively (Fig. 4). Meanwhile, the layer of vascular bundle sheath cells in the Wuyunjing23 cultivar rapidly decreased under higher N rates (Fig. 3b). In the W3668 cultivar, the xylem and phloem were poorly developed, and the layer of mechanical tissue cells also decreased (Fig. 3d).Fig. 3


Lodging Resistance of Japonica Rice (Oryza Sativa L.): Morphological and Anatomical Traits due to top-Dressing Nitrogen Application Rates.

Zhang W, Wu L, Wu X, Ding Y, Li G, Li J, Weng F, Liu Z, Tang S, Ding C, Wang S - Rice (N Y) (2016)

The thickness of the mechanical tissue of the N4 internodes culm in two japonica rice cultivars under different nitrogen rates. Different lowercase letters represent significant differences (P < 0.05) relative to the LN treatments for Wuyunjing23 and W3668, respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4930438&req=5

Fig4: The thickness of the mechanical tissue of the N4 internodes culm in two japonica rice cultivars under different nitrogen rates. Different lowercase letters represent significant differences (P < 0.05) relative to the LN treatments for Wuyunjing23 and W3668, respectively
Mentions: In the current study, the mechanical tissue and vascular bundle sheaths of the Wuyunjing23 cultivar were well-developed, whereas many hollow sclerenchyma cells were observed in the W3668 cultivar (Fig. 3). Top-dressing N rapidly altered the minute structures in the two japonica rice cultivars. For instance, with increasing top-dressing N application rates, the thickness of the mechanical tissue was remarkably reduced by 24.0 and 20.7 % in the Wuyunjing23 and W3668 cultivars, respectively (Fig. 4). Meanwhile, the layer of vascular bundle sheath cells in the Wuyunjing23 cultivar rapidly decreased under higher N rates (Fig. 3b). In the W3668 cultivar, the xylem and phloem were poorly developed, and the layer of mechanical tissue cells also decreased (Fig. 3d).Fig. 3

Bottom Line: The plant height, inner diameter of the minor axis (a2) and b2 increased significantly, but the area of the large vascular bundle (ALVB) and the area of the small vascular bundle (ASVB) decreased significantly and resulted in lower stem strength and a higher lodging index under higher top-dressing N conditions.Moreover, the ALVB and the ASVB decreased significantly, while the area of air chambers (AAC) increased rapidly.Top-dressing N application increased the plant height and inner culm diameter and decreased the ALVB and the ASVB of the Wuyunjing23 cultivar and caused deficient lignified sclerenchyma cells, lowered the ALVB and the ASVB, and increased the AAC of the W3668 cultivar resulting in weaker stem strength and a higher lodging index.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Collaborative Innovation Center for Modern Crop Production/National Engineering and Technology Center for Information Agriculture/ Key Laboratory of Crop Physiology and Ecology in Southern China, Nanjing Agricultural University, Nanjing, 210095, China.

ABSTRACT

Background: Lodging in rice production often limits grain yield and quality by breaking or bending stems. Excessive nitrogen (N) fertilizer rates are the cause of poor lodging resistance in rice, but little is known about the effect of top-dressing N application rates on the mechanical strength of japonica rice plants, especially how the anatomical structure in culms is affected by N. In this study, field experiments on two japonica rice varieties with three top-dressing N application rates, 0 kg N ha(-1) (LN), 135 kg N ha(-1) (MN), and 270 kg N ha(-1) (HN) as urea, were conducted. Wuyunjing23, a lodging-resistant japonica rice cultivar and W3668, a lodging-susceptible japonica rice cultivar were used. The lodging index, breaking strength, morphological and anatomical traits in culms were measured in this study.

Results: The visual lodging rate in japonica rice differed remarkably between genotypes and top-dressing N treatments. The higher lodging index of rice plants was primarily attributed to the weak breaking strength of the lower internodes. The longer elongated basal internodes were responsible for higher plant height and a higher lodging index. Correlation analysis showed that breaking strength was significantly and positively correlated with the thickness of the mechanical tissue but was significantly and negatively correlated with the inner diameter of the major axis (b2). With increasing top-dressing N rates, the sclerenchyma cells of the mechanical tissues and the vascular bundles of the Wuyunjing23 cultivar varied little. The plant height, inner diameter of the minor axis (a2) and b2 increased significantly, but the area of the large vascular bundle (ALVB) and the area of the small vascular bundle (ASVB) decreased significantly and resulted in lower stem strength and a higher lodging index under higher top-dressing N conditions. The culm diameter of the W3668 cultivar increased slightly with no significant difference, and the sclerenchyma cells in the mechanical tissues and vascular bundles showed deficient lignifications under high top-dressing N conditions. Moreover, the ALVB and the ASVB decreased significantly, while the area of air chambers (AAC) increased rapidly.

Conclusions: An improvement in the lodging resistance of japonica rice plants could be achieved by reducing the length of the lower internodes, decreasing the inner culm diameter and developing a thicker mechanical tissue. Top-dressing N application increased the plant height and inner culm diameter and decreased the ALVB and the ASVB of the Wuyunjing23 cultivar and caused deficient lignified sclerenchyma cells, lowered the ALVB and the ASVB, and increased the AAC of the W3668 cultivar resulting in weaker stem strength and a higher lodging index.

No MeSH data available.


Related in: MedlinePlus