Agriculture Reference
In-Depth Information
studies (Wen
et al., 2001; Idso et al., 2002) showed that the activity vari-
ance of enzymes is related to organic acid metabolism during development
of Robertson Navel orange fruit.
Rosenzweig et al. (1995)
investigated
the
potential impacts of global
climate change on fruit yield in the US were through simulations of cit-
rus. Simulated treatments included combinations of three increased tem-
perature regimes (+1.5, +2.5 and +5.0°C), and three levels of atmospheric
carbon dioxide (440, 530, and 600 ppm) in addition to control runs rep-
resenting current climatic conditions.
Downton et al.
(1987) recorded the
response to elevated CO
2
of 3-year-old fruiting Valencia orange scions
(
Citrus sinensis
Osbeck) on citrange rootstock (
C. sinensis
´
Poncirus tri-
foliata
(L.) Raf). Fruit yield from the CO
2
enriched trees did not differ
from the controls besides soluble solids content, dry weight, seed num-
ber or rind thickness. The progression of fruit coloration was more rapid
for the CO
2
enriched trees. These results indicated that fruit yield will
increased as global levels of CO
2
continued to rise, at least in those spe-
cies that experience source limitation during fruit development (Moretti
et al., 2010).
11.4
SOIL FERTILITY DYNAMICS
Dependence on curiosity about soil, exploring the diversity and dynam-
ics of this resource continues to yield fresh discoveries and insights. New
avenues of soil research are coupled by a need to understand soil in con-
text of climate change, greenhouse gases and carbon sequestration. The
major challenge is to reverse the side of nutrient loss and increase the
soil stocks through recapitalization initiatives. In recent years, there has
been an explosion of insight into genetic ecological and biogeochemical
dynamics of C-cycling processes in soils (Varallyay, 2010). These include:
plant and rhizosphere effects on soil respiration, the effects of microbial
communities on productivity and soil-C turnover, and interactions among
element cycles (role of organic nitrogen as a C and N source to microbes).
Fertilizers are the biggest source of greenhouse gases with reference to
horticulture. Large amounts of CO
2
and N
2
O are released into atmosphere
during the production of fertilizers; offsetting the amount of carbon se-
questered by trees. Nitrous oxide has more adverse effect than CO
2
over
climate change since each ton of N
2
O is equivalent to 300 tons of CO
2
. The
