Agriculture Reference
In-Depth Information
further increase in grain yield in cereals such as rice through breeding can only be accomplished with
an increase in total biological yield (Rahman, 1984) and thus the total straw yield. The highest GHI
exhibited by California lowland rice cultivars under direct seeding was 0.59 (Roberts et al., 1993).
Hasegawa (2003) reported that higher yields of rice cultivars were associated with higher dry mat-
ter production and both increased dry matter and GHI equally contributed to yield increases. Peng
et al. (2000) reported that the yield improvement of lowland rice cultivars released by International
Rice Research Institute (IRRI) in the Philippines after 1980 was due to increases in biomass pro-
duction. Similarly, Akita (1989) and Amano et al. (1993) reported that, when comparisons were
made among the improved semidwarf cultivars, higher yield was achieved by increasing biomass
production. Song et al. (1990) and Yamauchi (1994) reported that in hybrid rice having about 15%
higher yield than inbred mainly because of an increase in biomass production rather than GHI. Dry
matter production in rice has been reported to be significantly related to intercept photosynthetically
active radiation (IPAR) (Kiniry et al., 2001). CGR depends on the amount of radiation intercepted
by the crop and on the efficiency of conversion of intercepted radiation into dry matter (Sinclair
and Horie, 1989). Hence, it can be concluded that the production of sufficient dry matter of shoot is
important for improving the grain yield of rice.
López-Bellido et al. (2003) reported that high biomass is a prerequisite for achieving high faba
bean seed yields. Loss and Siddique (1997), Thomson et al. (1997), and Mwanamwenge et al. (1998)
also reported that seed yields of faba bean were positively correlated with the total dry matter pro-
duction at harvest. Linear relationships between biomass and seed yields were reported for soybeans
grown in Puerto Rico (Ramirez-Oliveras et al., 1997) and Australia (Mayers et al., 1991). Similarly,
Board et al. (1996) and Rao et al. (2002) also reported strong positive correlations between yields
and dry matter in soybeans grown in the United States. Dry matter production had highly significant
associations with grain yields of plants grown under relatively high heat environments (Reynolds
et al., 1994).
The shoot dry weight of dry bean was also significantly influenced by N fertilization. during
growth cycle, except at 23 days after sowing (Table 1.9). The shoot dry weight was maximum at
TABLE 1.9
Dry Matter Yield of Shoot (kg ha
−1
) of Dry Bean as Influenced by N Fertilization at
Different Growth Stages
Days after Sowing
N Rate
(kg ha
−1
)
23
44
60
78
93
0
80.0
118.8
220.0
658.8
1191.3
40
93.1
135.6
493.8
971.3
1442.5
80
95.0
178.1
813.8
1796.3
3340.0
120
77.5
171.3
827.5
2576.3
4503.8
160
71.3
239.4
1260.0
2261.3
5345.0
200
71.3
337.5
1658.8
3240.0
6593.8
F-test
NS
*
**
**
**
Regression Analysis
N rate (X) versus dry matter yield 23 days (Y) = 84.5759 + 0.1284X - 0.0011X
2
, R
2
= 0.1598
NS
N rate (X) versus dry matter yield 44 days (Y) = 117.3500 exp. (0.0023X) + 0.000011X
2
, R
2
= 0.4808*
N rate (X) versus dry matter yield 60 days (Y) = 218.6368 exp. (0.01734X) - 0.000038X
2
, R
2
= 0.8328*
N rate (X) versus dry matter yield 78 days (Y) = 615.2077 exp. (0.0147X) - 0.000034X
2
, R
2
= 0.8399*
N rate (X) versus dry matter yield 23 days (Y) = 1012.8120 exp. (0.0154X) - 0.000032X
2
, R
2
= 0.7135*
*,**, NS: Significant at the 5% and 1% probability levels and nonsignificant, respectively.
