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GROWTH, WATER
STATUS AND PHOTOSYNTHESIS IN TWO MAIZE (ZEA MAYS L.)
CULTIVARS AS AFFECTED BY SUPPLIED NITROGEN FORM AND DROUGHT STRESS
ZHANG LI XIN1*,
GAO MEI1, LI SHIQING2, LI SHENGXIU3 AND
LIANG ZONGSUO1
Abstract:
Hydroponic
experiments were conducted to investigate the effects of nitrogen form
on plant growth, water status and photosynthetic characteristics under
integrated root-zone drought stress (IR-DS) and non drought conditions
(non-DS) with two hybrids of maize cultivars Zhengdan 958 (ZD958) and
Jundan 20(JD20). On the 12th day of IR-DS, dry matter (DM) of
total plant, shoot and root, relative water content (RWC), chlorophyll
(Chl.) content, net photosynthetic rate (PN), stomatal
conductance (gs), transpiration rate (E) of
both cultivars in all N forms treatments as well as intercellular CO2
concentration (Ci) except NH4-treatment
were significantly decreased. However, lower DM production, RWC and
PN
as well as drought index (DI) were observed for JD20 than ZD958, thereby
the later could be considered as a drought tolerance cultivar
comparatively. By comparison with sole ammonium (NH4+),
sole nitrate (NO3-) and the mixture of NH4+
and NO3- both obviously increased DM of total
plant, shoot and root, RWC,
PN
and Chl. content while decreased gs, E and Ci
of both cultivars under drought. The effects of NO3--supplied
were superior than NH4++NO3--supplied
in the above responses. These impacts were more predominant in ZD958
than JD20. Further analysis of variation indicated that the impact of N
form treatment on most parameters measured except root DM were, in
general, less than water regime while higher than cultivar. It is,
therefore, concluded that an increase of ratio of NO3-
to NH4+ in nutrition solution could lead to an
enhancement in leaf RWC and photosynthesis of both cultivars subjected
to IR-DS, then result in biomass increase, thus alleviate of damage from
drought due to their obvious drought-resistance function based on its
nutritive role, especially for a drought tolerant cultivar.
1College
of Life Sciences and State Key Laboratory of Soil Erosion and Dryland
Farming, Northwest A & F
University, Yangling 712100, P. R. China
2State
Key Laboratory of Soil Erosion and Dryland Farming, Institute of Soil
and Water Conservation, Chinese Academy of
Sciences, Yangling 712100, P. R. China
3College
of Resource and Environment, Northwest & and F University, Yangling
712100, P. R. China
*Corresponding
author E-mail:
zhanglixinyangling88@yahoo.com.cn
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