Abstract
A mixed nitrate (NO3-) and ammonium (NH4+) supply can promote root growth in maize (Zea mays), however, the changes in root morphology and the related physiological mechanism under different N forms are still unclear. Here, maize seedlings were grown hydroponically with three N supplied in three different forms (NO3- only, 75/25 NO3-/NH4+ and NH4+ only). Compared with sole NO3- or NH4+, the mixed N supply increased the total root length of maize but did not affect the number of axial roots. The main reason was the increased total lateral root length, while the average lateral root (LR) length in each axle was only slightly increased. In addition, the average LR density of the 2nd whorl crown root under mixed N was also increased. Compared with sole nitrate, mixed N could improve the N metabolism of roots (such as the N influx rate, NR and GS enzyme activities and total amino content of the roots). Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation, and whether the NR mediated NO synthesis participates in this process needs further exploration. Meanwhile, an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation, and the changes in the sugar concentration in roots further proved this conclusion. Furthermore, the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation, in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway. This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize, which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.
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Claims 14
Claim · model-written summary
Mixed nitrogen increased total maize root length versus either sole N form.
- Treatment
- mixed N supplye0
- Outcome
- total root lengthe0
- Direction
- increasede0
- Comparator
- sole NO3- or NH4+e0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with sole NO3- or NH4+, the mixed N supply increased the total root length of maize but did not affect the number of axial roots”
e1“maize seedlings”
Claim · model-written summary
Mixed nitrogen did not affect axial root number versus either sole N form.
- Treatment
- mixed N supplye0
- Outcome
- number of axial rootse0
- Direction
- did not affecte0
- Comparator
- sole NO3- or NH4+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with sole NO3- or NH4+, the mixed N supply increased the total root length of maize but did not affect the number of axial roots”
e1“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased total lateral root length.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The main reason was the increased total lateral root length, while the average lateral root (LR) length in each axle was only slightly increased”
e1“maize seedlings”
Claim · model-written summary
Average lateral root length per axle increased only slightly.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The main reason was the increased total lateral root length, while the average lateral root (LR) length in each axle was only slightly increased”
e1“maize seedlings”
Claim · model-written summary
Mixed nitrogen increased mean lateral root density of the second whorl crown root.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average LR density of the 2nd whorl crown root under mixed N was also increased”
e1“maize seedlings”
Claim · model-written summary
Mixed N improved root N influx rate versus sole nitrate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with sole nitrate, mixed N could improve the N metabolism of roots (such as the N influx rate, NR and GS enzyme activities and total amino content of the roots)”
e1“maize seedlings”
Claim · model-written summary
Mixed N improved root NR and GS enzyme activities versus sole nitrate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with sole nitrate, mixed N could improve the N metabolism of roots (such as the N influx rate, NR and GS enzyme activities and total amino content of the roots)”
e1“maize seedlings”
Claim · model-written summary
Mixed N improved root total amino content of the roots versus sole nitrate.
- Treatment
- mixed Ne0
- Outcome
- total amino content of the rootse0
- Direction
- improvee0
- Comparator
- sole nitratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with sole nitrate, mixed N could improve the N metabolism of roots (such as the N influx rate, NR and GS enzyme activities and total amino content of the roots)”
e1“maize seedlings”
Claim · model-written summary
Inhibitor experiments linked mean lateral root length increase under mixed N to nitrogen assimilation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation”
e1“maize seedlings”
Claim · model-written summary
The authors inferred shoot-to-root carbon transport might not be key to lateral root elongation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“C transportation from shoots to roots may not be the key factor in mediating lateral root elongation”
e1“maize seedlings”
Claim · model-written summary
Root sugar concentration changes supported the conclusion about carbon transport.
- Outcome
- changes in the sugar concentration in rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the changes in the sugar concentration in roots further proved this conclusion”
e1“maize seedlings”
Claim · model-written summary
Auxin synthesis and transport in axial roots may have a key role in lateral root elongation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation”
e1“maize seedlings”
Claim · model-written summary
ZmPIN1B expression may participate in the auxin pathway linked to lateral root elongation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway”
e1“maize seedlings”
Claim · model-written summary
ZmPIN9 expression may participate in the auxin pathway linked to lateral root elongation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway”
e1“maize seedlings”
The same questions in other papers
nitrogen · growth · Zea mays (maize)Positive and negative results
618 papers in the same direction as this paper · 115 in the opposite direction · 14 reporting no difference from an alternative
- no effect
- positive
- positive
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