Nitrogen deficiency frequently occurs at agricultural soil because of NH3 volatilization to the environment which results in low urea-N use efficiency by rice plants. A pot experiment was conducted to assess the synergistic effects of a mixture of rice straw and rice husk biochars (RSRH) on (1) total N, soil exchangeable NH4+, and available NO3−, and (2) uptake of N, P, and K in rice plant. RSRH biochar at 5 and 10 t ha−1 had significantly minimized ammonia volatilization by 33.5% and 40.7%. Further, RSRH biochars also had significantly increased available NH4+, NO3−, available P, and available K in the soil over T1. In line to increase in soil nutrient availability, the rice plant height, tiller number, greenness, and panicle number were increased. This resulted in an increase of nutrient uptake, use efficiency, and dry matter production of the rice plant. RSRH biochar altered the soil environment by minimizing NH3 loss and increasing soil nutrients for efficient plant uptake.

Fungi are a diverse group of microorganisms that play many roles in human livelihoods. However, the isolation of potential fungal species is the key factor to their utilization in different sectors, including the enzyme industry. Hence, in this study, we used two different fungal repositories—soil and weed leaves—to isolate filamentous fungi and evaluate their potential to produce the cellulase enzyme. The fungal strains were isolated using dichloran rose bengal agar (DRBA) and potato dextrose agar (PDA). For cellulase enzyme production, a rice straw submerged fermentation process was used. The enzyme production was carried out at the different incubation times of 3, 5, and 7 days of culture in submerged conditions with rice straw. Fungal identification studies by morphological and molecular methods showed that the soil colonies matched with Trichoderma reesei, and the weed leaf colonies matched with Aspergillus awamori. These species were coded as T. reesei UMK04 and A. awamori UMK02, respectively. This is the first report of A. awamori UMK02 isolation in Malaysian agriculture. The results of cellulase production using the two fungi incorporated with rice straw submerged fermentation showed that T. reesei produced a higher amount of cellulase at Day 5 (27.04 U/mg of dry weight) as compared with A. awamori (15.19 U/mg of dry weight), and the concentration was significantly different (p < 0.05). Our results imply that T. reesei can be utilized for cellulase production using rice straw.

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Although 2,4-di-tert-butylphenol (2,4-DTBP) has demonstrated strong phytotoxic effect on various weedy plants in previous findings, research on its pre-emergence herbicidal activity in the soil is still scanty. The aim of this study was to investigate the effects of two soil types on pre-emergence herbicidal activity and persistence of 2,4-DTBP. The bioassay was carried out in a growth chamber where goosegrass [Eleusine indica (L.) Gaertn.] seeds were sown in different rates of 2,4-DTBP in two soil series under sterilized and non-sterilized soil conditions. Bioassays of each treatment were conducted in four replicates and arranged in completely randomized design. 2,4-DTBP exhibited potent pre-emergence activity as a root inhibitor where it completely inhibited (100% inhibition) of the root growth of E. indica in sandy loam soil at an application rate of 6.14 kg ai/ha. 2,4-DTBP was rapidly detoxified in silt loam soil as a result of high microbial activity where it completely lost its phytotoxicity by giving 100% emergence within 10 weeks even it was applied at an application as high as 20.4 kg ai/ha. However, 2,4-DTBP remained highly phytotoxic in sandy loam soil where it reduced the root and shoot growth by 47 and 36%, respectively, throughout 10 weeks duration of the investigation. The presence of microbes in non-sterilized soil further suggest that soil microbes may modify the chemical structure of the 2,4-DTBP, which in turn decreased its toxicity. The high level of pre-emergence herbicidal activity in conjunction with its biodegradation in silt loam soil imply that 2,4-DTBP may have potential for development as a natural-soil applied herbicide

Weed has become one of the most serious problems in aerobic rice systems. Weed management in aerobic rice system needs a manipulation of optimum N fertilizer application to control the weed and simultaneously enhance aerobic rice growth performance. In this study, three types of N sources (urea, ammonium sulphate and ammonium nitrate) with concentration starting from (0, 60, 120, 180 and 240 kg ha -1 ) were evaluated for effective control of the bioassay species, Eleusine indica, while observing the rice injury level. The data on weed (emergence and shoot fresh weight), while rice growth (root length, shoot fresh weight, shoot height and leaf greenness) was collected in this study. It was found that urea at a higher application rate of 240 kg ha -1 strongly inhibit the emergence and shoot growth of E. indica by >78%. Conversely, ammonium sulphate and ammonium nitrate gave moderate inhibition (58-65% inhibition) on weed emergence and shoot growth at higher application rates of 240 kg ha -1 , respectively. Significant stimulation effect on rice root growth, shoot height, shoot fresh weight and leaf greenness was noticed at a low application rate of 60 kg ha -1 urea, while ammonium sulphate and ammonium nitrate only exerts its stimulation effect starting at 120 kg ha -1 . Stimulation effect on the rice growth was likely negligible at 0 and 4 DAS across urea, ammonium sulphate and ammonium nitrate application rates. However, the rice plants growth increases with increasing growth stage. The finding suggest that application of urea at 240 kg ha -1 starting from 8 DAS of rice growth stage was the most efficient application rate in inhibiting E. indica with the stimulation effect on the growth of rice seedlings.