Boron Deficiency in Rice in Pakistan: A Serious Constraint to Productivity and Grain Quality

Abstract

Recently, boron (B) deficiency has been established to be a serious constraint to crop productivity in Pakistan. Despite being categorized as tolerant to B deficiency, we suspected that rice also suffers with this nutrient disorder. Multi-location, multi-year fi eld experiments were conducted during 2002–2004 in B-deficient (HWE B, 0.21–0.42 mg kg⁻¹), calcareous (CaCO₃, 1.5–5.7%) soils in the major rice-growing areas of Punjab and Sindh. Basmati type rice cultivars, i.e., Super Basmati and Basmati—385, and coarse grain cultivars, i.e., IR—6 and KS—282, were included in the study. Average paddy yield increase with B was 21% each in cv. Super Basmati and cv. Basmati-385, 30% in cv. IR—6, and 14% in cv. KS—282. The substantial yield increases were primarily the consequence of reduced panicle sterility and increased productive tillers. Better B nutrition of plants also enhanced milling recovery and head rice recovery, and improved kernel quality traits, like stickiness, elongation-upon-cooking, and bursting-upon-cooking. Thus, soil B deficiency not only hampers rice productivity but also impairs its cooking quality. The economics of B use in rice is highly attractive, with value-cost ratios of 45:1 to 26:1 in various cultivars. Cooking quality improvement and residual benefi cial effect of B are additional benefi ts. Consequently, this research has led to B use recommendation (@0.75 kg B ha-1) in rice in Punjab province. As fertilizer B use adoption may remain problematic in the foreseeable future, rice plant improvement for B use effi ciency merits attention of biotechnologists.