A. Rashid et al., DIAGNOSING BORON DEFICIENCY IN RAPESEED AND MUSTARD BY PLANT ANALYSISAND SOIL TESTING, Communications in soil science and plant analysis, 25(17-18), 1994, pp. 2883-2897
Boron (B) deficiency is a widespread nutritional disorder in crop plan
ts, including rapeseed and mustard. However, plant analysis and soil t
esting diagnostic criteria for B are inadequately reported in the lite
rature. Therefore, greenhouse and incubation studies were carried out
using a B-deficient alkaline calcareous soil (hot water extractable B,
0.11 mg/kg) of Pakistan to determine the internal and soil test B req
uirement of rapeseed and mustard. Boron fertilization substantially en
hanced the growth of both species; the maximum increase in grain yield
was 43% for rapeseed and 36% for mustard over the yield of respective
control plants. Fertilizer requirement for near-maximum (95%) grain y
ield was 0.7 mg B/kg for rapeseed and 0.9 mg B/kg for mustard. Critica
l plant tissue B concentration in rapeseed was 32 mg/kg in whole shoot
s and 38 mg/kg in most recently matured leaves. However, internal B re
quirement of mustard was relatively greater: i.e. 41 mg/kg in whole sh
oots and 49 mg/kg in leaves. The three soil tests studied, hot water,
hydrochloric acid (HCl), and mannitol, were almost equally effective i
n determining soil B status. Because of simplicity and low cost, howev
er, the HCl method appears superior than the other two for routine B a
nalysis. Critical soil B levels (mg/kg) for rapeseed were: hot water,
0.5; HCl, 0.45; and mannitol, 0.4. Similar to internal B requirements,
soil test critical B levels (mg/kg) were also greater for mustard, i.
e. hot water, 0.6; HCl, 0.55; and mannitol, 0.48.