Agriculture Reference
In-Depth Information
genotypes on permanent raised beds were different from those in conventionally
tilled plots, suggesting the presence of significant genotype × environment interac-
tions. In the same trial, three check varieties of wheat, namely PBW550, HD2967,
and DBW17, developed for and bred under conventional tillage conditions, were
repeated after every 24 entries and therefore replicated 30 times in the trial to test
their adaptability for zero-till conditions.
The average yield of check wheat cultivars planted in a maize-wheat cropping
system under conventionally tilled and permanent raised bed systems are given in
Table 5.2.
The yield responses of the three check cultivars under two production environ-
ments, namely zero-till and conventional till systems, were noticeably interesting
(Figure 5.4). The cultivar PBW550 showed specific adaptation for conventional till
conditions, and its performance was at par with the other two check varieties under
conventional till. However, PBW550 was significantly poor than other two wheat
cultivars under permanent zero-till conditions. The cultivar DBW17, on the other
hand, performed best under the zero-till condition. It was observed that HD2967
was statistically at par (neutral) to tillage and crop establishment options. In the
same study, specific genotypic adaptation was also observed for different cropping
systems, as the top-ranking wheat genotypes were different for the three major
rice-wheat, maize-wheat, and pearl millet-wheat cropping systems, indicating the
existence of a genotype × cropping system interaction also. With accumulating evi-
dences on the effect of CA on the cereal-soil dynamic, there is every likelihood
of a prevalence of the genotype × system interaction. Future gains in grain yield,
therefore, can be harnessed with more detailed knowledge of the responses of each
species to the environment and a precise description of the genotypic variability in
promising traits (i.e., a fine-tuned phenotyping for developmental attributes), which
seems to be valuable for any cropping system.
5.6.5 V
Ernalization
g
EnES
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d
EVEloping
a
ltErnatE
S
uStainablE
W
hEat
-b
aSEd
c
ropping
S
yStEmS
Increase in yield in many crops such as wheat has largely been achieved by adjust-
ing the plant phenology as per the requirements of the growing condition in specific
regions. Knowledge about genetic factors governing adaptability aids crop breeding
for yield potential enhancement. Worldwide, the genetic gain has been limited under
dry conditions. More gain can be achieved for these conditions by selecting and com-
bining synergetic traits (Dingkuhn et al. 2006). Phenological development, undoubt-
edly the most important attribute (Richards 1996; Passioura 1996, 2002; Villegas et
al. 2000; Araus et al. 2002; González et al. 2003; Slafer et al. 2005), allows the crop
to either escape stresses or avoid the coincidence of the most sensitive phases with
the most likely occurrence of stress. Wheat is generally planted in the first fortnight
of November in South Asia to avoid terminal heat stresses and moisture shortages
resulting in shriveled grains and reduced yields, to provide a more favorable envi-
ronment for crop growth and avoid early and late heat stress. Genetic gains in wheat
yield in the last two decades in the northern plain of India have largely been realized
