Agriculture Reference
In-Depth Information
a
a
a
0.60
ab
b
0.50
0.40
0.30
0.20
0.10
0
Lowland rice genotypes
FIGURE 3.32
NHI of five lowland rice genotypes. (From Fageria, N. K. 2007a. Yield physiology of rice.
J.
Plant Nutr
. 30:843-879. With permission.)
The author studied the NHI of dry bean genotypes (Table 3.14). The N rate genotype signifi-
cantly influenced NHI and the N × G interaction was significant for this trait (Table 3.14). The
average N harvest index at a low N rate was 0.63 and at a high N rate it was 0.75. This means
that overall 63% of the total N accumulated in the bean plant (grain plus straw) was translocated
to the grain at a low N rate. At a higher N rate, the translocation was 75% of the total N uptake.
NHI is a measure of N partitioning in bean, which provides an indication of how efficiently the
plant utilized the acquired N for grain production. Harvest index was having significant linear
relationship with grain yield (Y = −18.3691 + 46.0572X, R
2
= 0.4044*). This is proved by the
highest-yielding genotypes, that is, CNFC 7827, CNFP 7677, and CNFP 7775 at a higher N rate
were also having higher N harvest indices. Genetic variability for NHI has been reported in crop
plants (Rattunde and Frey, 1986). High NHI is associated with efficient utilization of N (Welch
and Yong, 1980). Selecting crop genotypes for high NHI may simultaneously improve grain yield
(Loffler and Busch, 1982). Generally, NHI values are higher in legumes compared to cereals
(Fageria et al., 2006). Bender et al. (2013) reported that the NHI of corn was 58% and Karlen
(1988) reported that it was 60%.
3.7 PLANT RESPONSE TO APPLIED NITROGEN
Soil and plant analyses are the common practices for identifying nutritional deficiencies in crop
production. The best criterion, however, for diagnosing nutritional deficiencies in annual crops is
through evaluating crop responses to applied nutrients. If a given crop responds to an applied nutri-
ent in a given soil, this means that the nutrient is deficient for that crop. The relative decrease in yield
in the absence of a nutrient, as compared to an adequate soil fertility level, can give an idea of the
