TY - JOUR
T1 - High Nitrogen Availability Limits Photosynthesis and Compromises Carbohydrate Allocation to Storage in Roots of Manihot esculenta Crantz
AU - Omondi, John Okoth
AU - Lazarovitch, Naftali
AU - Rachmilevitch, Shimon
AU - Yermiyahu, Uri
AU - Sperling, Or
N1 - Publisher Copyright:
© Copyright © 2019 Omondi, Lazarovitch, Rachmilevitch, Yermiyahu and Sperling.
PY - 2019/9/11
Y1 - 2019/9/11
N2 - Cassava (M. esculenta Crantz), feeding countless people and attracting markets worldwide, is a model for traditional crops that need physiology-based fertigation (fertilization through irrigation) standards in intensive cultivation. Hence, we studied the effects of 10 to 200 mg L-1 nitrogen (N) fertigation on growth and yields of cassava and targeted alterations in their photosynthetic, transpiration, and carbohydrate management. We found that increasing irrigation N from 10 to 70 mg L-1 increased cassava’s photosynthesis and transpiration but supported only the canopy’s growth. At 100 mg N L-1 cassava reached a threshold of sugar in leaves (∼47 mg g-1), began to accumulate starch and supported higher yields. Yet, at 200 mg N L-1, the canopy became too demanding and plants had to restrain transpiration, reduce photosynthesis, decrease carbohydrates, and finally lower yields. We concluded that the phases of cassava response to nitrogen are: 1) growth that does not support yields at low N, 2) productive N application, and 3) excessive use of N. Yet traditional leaf mineral analyses fail to exhibit these responses, and therefore we propose a simple and inexpensive carbohydrate measurement to guide a precise use of N.
AB - Cassava (M. esculenta Crantz), feeding countless people and attracting markets worldwide, is a model for traditional crops that need physiology-based fertigation (fertilization through irrigation) standards in intensive cultivation. Hence, we studied the effects of 10 to 200 mg L-1 nitrogen (N) fertigation on growth and yields of cassava and targeted alterations in their photosynthetic, transpiration, and carbohydrate management. We found that increasing irrigation N from 10 to 70 mg L-1 increased cassava’s photosynthesis and transpiration but supported only the canopy’s growth. At 100 mg N L-1 cassava reached a threshold of sugar in leaves (∼47 mg g-1), began to accumulate starch and supported higher yields. Yet, at 200 mg N L-1, the canopy became too demanding and plants had to restrain transpiration, reduce photosynthesis, decrease carbohydrates, and finally lower yields. We concluded that the phases of cassava response to nitrogen are: 1) growth that does not support yields at low N, 2) productive N application, and 3) excessive use of N. Yet traditional leaf mineral analyses fail to exhibit these responses, and therefore we propose a simple and inexpensive carbohydrate measurement to guide a precise use of N.
KW - carbohydrates
KW - fertigation
KW - nitrogen
KW - physiological indicators
KW - root-crops
UR - http://www.scopus.com/inward/record.url?scp=85072843568&partnerID=8YFLogxK
U2 - 10.3389/fpls.2019.01041
DO - 10.3389/fpls.2019.01041
M3 - Article
AN - SCOPUS:85072843568
SN - 1664-462X
VL - 10
JO - Frontiers in Plant Science
JF - Frontiers in Plant Science
M1 - 1041
ER -