304 Progressive Agriculture 29 (4): 304-312, 2018 ISSN: 1017 - 8139 Effect of nitrobenzene on growth and yield of boro rice B Chowdhury 1 , MHK Howlader 1 ⃰ , MK Hossain 2 , MC Sikder 1 , MM Hasan 1 1 Department of Agricultural Botany, Patuakhali Science and Technology University, Patuakhali 8602, Bangladesh; 2 Department of Soil Science, Patuakhali Science and Technology University, Patuakhali-8602, Bangladesh. Introduction Rice (Oryza sativa L.) is the dominant food crop in Bangladesh. Bangladesh ranks 3rd position in rice growing area and 4th position in production among rice growing countries of the world (FAO 2008). In Bangladesh among cereals, the primary position is occupied by rice with about 80 percent of the total arable land is dedicated to rice cultivation (BBS 2014). Integrated use of organic manure and chemical fertilizers would be quite promising not only in providing greater stability in production, but also in maintaining better soil fertility (Tilahun et al., 2013). In Bangladesh, about 80% of the total lands are used for rice cultivation. Rice contributes 91.1% of the total grain production and covers 74% of the total calorie intake for the people of Bangladesh. (MOA, 2001), although rainfall pattern is an important factor for rice production (Rokonuzzaman et al., 2018). Area under Bangladesh is the 5 th largest country of the world with respect to rice cultivation. Rice is cultivated in about 28489 thousand acres land and total annual production is 33542TM. tons, with an average of 1177 kg acre -1 (BBS, 2011). As reported in Aziz et al. (2009) spraying of plant growth substances containing Nitrobenzene Abstract The present experiment was conducted at the research field of Patuakhali Science and Technology University (PSTU), Patuakhali during the period from December 2013 to March 2014 to evaluate the effect of Nitrobenzene as plant growth regulators on growth and yield parameters of Boro Rice. It also observed the comparative growth and yield performance of foliar application Nitrobenzene ( 0, 1.0, 3.0 and 5.0 ml L –1 ). Data were collected on Plant height; number of leaves plant –1 ; number of total, effective and non–effective tillers hill –1 ; leaf area (LA); leaf area index (LAI); total dry matter (TDM); Crop and relative growth rate (CGR and RGR); and Yield and yield contributing characters such as length of root; length of panicle; number of total, sterile and non–sterile spikelets panicle –1 ; 1000–grain weight; grain, straw and biological yield and harvest index (HI). The experiment was laid out in a completely randomized block design (RCBD) with three replications. The collected data were analyzed statistically and means were adjudged by DMRT at 5% level of probability. The treatments Nitrobenzene @ 3.0 ml L –1 as foliar application gave the highest performance in respect of plant height (90.39 cm), LAI (3.514), TDM (19.17 g plant –1 ), effective tiller (20.33 hill –1 ), total tillers (22.73 hill –1 ), panicle length (26.01 cm),non sterile spikelets (134.70 panicle –1 ), total spikelets (155.80 panicle –1 ), 1000–grain weight (28.21 g), grain yield (5.86 t ha –1 ), straw yield (8.44 t ha –1 ), biological yield (14.29 t ha –1 ) and HI (41.00%) of boro rice. Key words: Nitrobenzene, growth , yield, boro rice Progressive Agriculturists. All rights reserved *Corresponding Author: hhkabir63@gmail.com