Micronutrient deficiencies in rainfed calcareous soils of Pakistan. III. Boron nutrition of sorghum

Abstract

Boron (B) deficiency in crops is a major micronutrient disorder particularly in alkaline-calcareous soils. A nutrient indexing of rainfed sorghum [Sorghum bicolor (L.) Merr; cv. in the Potohar plateau of Pakistan revealed B deficiency in 50% of the 140 sampled fields in Jehlum district and 115 fields in Chakwal district. Hot water extractable (HWE) B in the associated soils, however, indicated more widespread B deficiency. The 255 sampled fields represented 21 soil series: 100 belonging to Alfisols, 63 to Entisols, 50 to Inceptisols, and 42 to Aridisols. Boron fertility varied in various soil types; the minimum HWE B (0.25 mg/kg) was noted in Calci Ustochrepts and the maximum (0.69 mg/kg) in Fleventic Ustochrepts. Boron fertilization of an alkaline calcareous Typic Ustorthents (HWE B, 0.11 mg/kg) increased grain yield up to 32% in improved sorghum (cv. PARC-SS-1) and 29% in local sorghum (cv. Potohar 4-8) over the respective control yields. Fertilizer requirements for near-maximum (95%) grain yield was 1.2 mg B/kg for the improved and 0.6 mg B/kg for local cultivar; higher fertilizer requirement of improved sorghum may be attributed to its greater biomass production. Critical plant tissue B concentration in improved sorghum was 17 mg/kg in whole shoots and 25 mg/kg in most recently matured leaves. Contrary to its 441 Copyright © 1997 by Marcel Dekker, Inc. Downloaded by [University of Connecticut] at 22:16 13 October 2014 442 RASHID, RAFIQUE, AND BUGHIOlesser fertilizer requirement, internal B requirement of local sorghum was greater, i.e., 18 mg/kg in whole shoots and 31 mg/kg in leaves. The three soil tests for B, hot water, hydrochloric acid (HC1), and mannitol were almost equally effective in evaluating soil B fertility. Soil test critical B levels (mg/ kg) for improved sorghum were: hot water, 0.48; HC1, 0.43; and mannitol, 0.37. Contrary to its internal B requirements, soil test critical B levels (mg/ kg) were slightly lower for local sorghum, i.e., hot water, 0.45; HC1, 0.40; and mannitol, 0.36. Thus, local sorghum appeared more efficient in utilizing soil B. As soil test critical levels as well as fertilizer requirement were greater for improved sorghum, a much widespread B deficiency is expected in this cultivar if grown on alkaline calcareous soils of the Potohar plateau.

Boron Deficiency in Soils and Crops: A Review

“…Seed yield increases in groundnut have been reported from 9 to 12% by borax application in B deficient Chinese soil (0.3-0.5 mg B kg -1 ) by Zhang et al (1986). A 10% increase in pod yield of groundnut after B fertilization over the control) was obtained with 1 kg B ha -1 (Rashid et al, 1997) in Pakistan. Encouraging responses of groundnut to B application have also been recorded in India, with average pod yield increase of 180 kg ha -1 (Takkar & Nayyar, 1984).…”

“…Groundnut is also one of the important cash crops of the Potohar plateau in the Punjab province of Pakistan. The crop is grown under rainfed conditions on relatively poorly fertile alkaline-calcareous soils with no adequate fertilization history (Rashid et al, 1997). Its average yield in Pakistan is reported to be 921 kg ha -1 (Anonymous, 2009) and is much less as compared with the average yields of some other countries, e.g., in China, 2180 kg ha -1 (Luo et al, 1990).…”

“…A curvilinear relation was exhibited between Ca/B ratio in shoot and relative shoot dry matter. In this regard, further work is warranted on Ca/B utilizing association for ameliorating B deficient calcareous soils (Rashid et al, 1997).…”

“…Nonetheless, B use in Pakistan is not a promising practice in groundnut as it is a low-input high-risk rainfed crop. Since internal B requirements of various groundnut genotypes vary greatly; a viable and practical solution of managing B deficiency in groundnut could be the screening of the available germplasm with respect to its sensitivity to B deficiency (Rashid et al, 1997).…”

Internal Boron Requirement of Young Sunflower Plants: Proposed Diagnostic Criteria

“…However, critical B concentration in 8-week-old whole shoots was much lesser (i.e., 37 mg B kg 2l ). In accordance with the guidelines provided by Reuter et al (1997) and Jones et al (1991), internal B requirement of young sunflower (a dicot) is much greater than similar-age plants of cereals (monocots), such as wheat (4 -6 mg B kg 21 ) (Rashid et al 2002b) and sorghum (17 -18 mg B kg 21 ) (Rashid et al 1997). The estimated internal B requirement of young plants, in this study, is even higher than the suggested critical concentration range for youngest fully expanded leaves of sunflower (i.e., 31 -38 mg B kg 21 ) (Blamey et al 1979).…”