SALINITY TOLERANCE OF RICE AS AFFECTED BY BORON NUTRITION

Abstract

The effect of boron on the yield and ionic composition of rice cultivars having differential salt tolerance, grown in artificially prepared saline (ECi 9 dS m'1 ; SAR 5.5) and saline-sodic soils (EC, 9 dS m'; SAR 28.2) was investigated. The cultivars were: KS282 (salt tolerant), IR-28 (salt sensitive) and BG 402-4 (mixed behaviour). Recommended dose of N, P and K was applied with and without B @ 0, 1.5, 3.0 and 6.0 kg ha-'. The cultivars were allowed to grow up to maturity. Before panicle initiation, the top three leaves from mother shoot of each plant were collected and processed for analysis. The results revealed an ameliorative effect of B supply to salt affected soils in enhancing yield and growth of rice regardless of their salinity tolerance. Although the ameliorative effect on paddy and straw yield and paddy:straw ratio was recorded at all external B supplies compared with control, the highest improvement was recorded at 1.5 kg B ha' in the saline and saline sodic soils. Nevertheless, the highest B supply @ 6 kg B ha'' had shown an adverse affect on paddy and straw production in saline-sodic soils in alt the cultivars compared with alt the other B rates and control. The overall yields, in all the cultivars, were higher in saline than saline sodic soils. The leaf Na and Cl concentrations were the lowest, whereas K:Na was the highest in all rices in saline and saline sodic soils because of B application ® 1.5 kg B ha'1 . Although the absolute paddy yield was the highest in KS-282 both in saline and saline sodic soils, the ratio of improvement in paddy yield was the highest in both the soils in the case of IR-28 (the salt- sensitive cultlvar). Similarly, the spike sterility was minimum in all cultivars in both the soils at 1.5 kg B ha'. The investigations clearly demonstrate the beneficial effect of B ® 1.5 kg B ha' for improving paddy production from adverse lands