Search

Black rice is considered as super food due to its various health benefits to the human being. In Bangladesh this rice is cultivated in a very limited area of Chittagong hill tracts and its cultivation technique in plain land ecosystem is still unknown. Therefore, a study was undertaken to evaluate the performance of few black rice cultivars cultivated year-round in plain land environment. The experiment was performed at the Agronomy Field Laboratory of Bangladesh Agricultural University, Mymensingh. The experiment comprised two factors viz. A) three rice cultivars: Kongnam ene, Gelong ni and Gelong se; and B) Twelve date of transplanting starting from 01 July 2018 to 01 June 2019. The experiment was laid out in a split plot design where date of transplanting was distributed in main plots and rice cultivars were allocated in sub plots. It has been found that cultivar Kongnam ene can be cultivated as a short duration variety as it required only 40 days to panicle initiation, 60 days to flowering and 80 days to harvesting after transplanting. All the three cultivars can be cultivated in all the three seasons viz. aus, aman and boro. The cultivar Gelong ni produced significantly highest grain yield (4.0 t/ha) among the cultivars when transplanted in January (boro season).

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during February to June 2017 to study the feasibility of different direct seeded rice based intercropping systems under varying fertilizer management. The experiment was conducted in afactorialrandomized complete block design with three replications. Four leafy vegetables viz., gimakalmi, Indian spinach, red amaranth andjute were intercropped with dry direct seeded boro rice (cv. BRRI dhan28) following three fertilizer dose such as 100, 75 and 125% of recommended fertilizer, and sole rice was also maintained as control. Rice yield was the highest (3.87t ha-1) in sole cropping, and intercroppingresulted insignificant rice yield reduction. Although inintercropping rice yielddecreased, but increased both gross margin and benefit cost ratio (BCR) as compared to rice sole cropping. Among the vegetables, gimakalmi performed the best followed by red amaranth in terms of yield and 125% recommended fertilizer was the best fertilizer dose. Gimakalmi intercropped with rice following 125% recommended fertilizer showed the highest gross return and BCR (2.53). Therefore, vegetables like gimakalmi and red amaranth couldbe recommended as intercrop with dry direct seeded winter rice with 125% recommended fertilizer for better productivity and higher economicreturn. Bangladesh Agron. J. 2019, 22(2): 103-112

An experiment was carried out to study the effect of date of sowing and level of phosphorus on the yield, yield components and seed protein content of faba bean (Vicia faba L.) at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during November 2018 to March 2019 to study the influence of sowing date and phosphorous fertilization on the growth, yield and quality of faba bean (V. faba). Three date of sowing viz. 25 November, 5 December, 15 December and five levels of phosphorus viz., 0, 10, 20, 30, 40 kg P ha-1 were used in this experiment laid out in a randomized complete block design with three replications. At 60 DAS, 25 November sowing fertilized with 40 kg P ha-1 showed significant influence on all characters except dry matter production. Early sowing on 25 November produced the tallest plant (42.95 cm), highest number of branches plant-1 (8.31), number of pods plant-1 (49.87), 1000-seed weight (97.55 g), seed yield (1.21 t ha-1), stover yield (1.98 t ha-1) and seed protein content (31.54%) while the corresponding lowest values were recorded from late sowing on 15 December. The crop fertilized with 40 kg P ha-1 produced the highest number of branches plant-1 (8.33), number of pods plant-1 (49.05), 1000-seed weight (97.40 g), seed yield (1.33 t ha-1), stover yield (2.28 t ha-1) and seed protein content (38.17%) while control treatment (0 kg P ha-1) produced the lowest values of all parameters. In case of interaction, the highest number of pods plant-1 (58.42), seed yield (1.59 t ha-1), stover yield (2.44 t ha-1) and protein content in seeds (39.60) were recorded with 25 November sowing fertilized with 40 kg P ha-1 whereas the lowest seed yield (0.54 t ha-1), stover yield (1.32 t ha-1) and seed protein content (25.90%) were obtained from 15 December sowing along with control treatment. Therefore, early sowing (25 November) with 40 kg P ha-1 appears as the promising combination for higher yield and seed protein content of faba bean.

Abiotic stresses varyingly affect the grain composition and quality of food legumes. This paper is aimed at discussing the impact of abiotic stresses on the grain composition and quality of food legumes. As protein is the main grain constituent of food legumes for which it is being consumed by humans as a cheap protein source, abiotic stresses such as heat, cold, drought, salinity and heavy metals alter this grain protein content in different dimensions for different food legumes. Moreover, other valuable constituents such as starch, soluble sugar, oil, fatty acid and fiber content are affected differently by the abiotic stresses. The diverse impact of these abiotic stresses ultimately declines the grain quality and yield of food legumes. As food legumes play a vital role in the nutritional diet of millions of people in the world and are occasionally denoted as the meat of poor people, it is important to recognize that the sustainable production of food legumes, even under various environmental stresses, has the potential to ensure protein security for people globally. Therefore, it has become a necessity to improve the productivity and quality of food legumes under abiotic stresses through proper crop management and improved breeding strategies, thus enhancing food and economic security to the farmers, particularly in the developing countries of the world.

Grain legumes are important sources of proteins, essential micronutrients and vitamins and for human nutrition. Climate change, including drought, is a severe threat to grain legume production throughout the world. In this review, the morpho-physiological, physio-biochemical and molecular levels of drought stress in legumes are described. Moreover, different tolerance mechanisms, such as the morphological, physio-biochemical and molecular mechanisms of legumes, are also reviewed. Moreover, various management approaches for mitigating the drought stress effects in grain legumes are assessed. Reduced leaf area, shoot and root growth, chlorophyll content, stomatal conductance, CO2 influx, nutrient uptake and translocation, and water-use efficiency (WUE) ultimately affect legume yields. The yield loss of grain legumes varies from species to species, even variety to variety within a species, depending upon the severity of drought stress and several other factors, such as phenology, soil textures and agro-climatic conditions. Closure of stomata leads to an increase in leaf temperature by reducing the transpiration rate, and, so, the legume plant faces another stress under drought stress. The biosynthesis of reactive oxygen species (ROS) is the most detrimental effect of drought stress. Legumes can adapt to the drought stress by changing their morphology, physiology and molecular mechanism. Improved root system architecture (RSA), reduced number and size of leaves, stress-induced phytohormone, stomatal closure, antioxidant defense system, solute accumulation (e.g., proline) and altered gene expression play a crucial role in drought tolerance. Several agronomic, breeding both conventional and molecular, biotechnological approaches are used as management practices for developing a drought-tolerant legume without affecting crop yield. Exogenous application of plant-growth regulators (PGRs), osmoprotectants and inoculation by Rhizobacteria and arbuscular mycorrhizal fungi promotes drought tolerance in legumes. Genome-wide association studies (GWASs), genomic selection (GS), marker-assisted selection (MAS), OMICS-based technology and CRISPR/Cas9 make the breeding work easy and save time in the developmental cycle to get resistant legumes. Several drought-resistant grain legumes, such as the chickpea, faba bean, common bean and pigeon pea, were developed by different institutions. Drought-tolerant transgenic legumes, for example, chickpeas, are developed by introgressing desired genes through breeding and biotechnological approaches. Several quantitative trait loci (QTLs), candidate genes occupying drought-tolerant traits, are identified from a variety of grain legumes, but not all are under proper implementation. Hence, more research should be conducted to improve the drought-tolerant traits of grain legumes for avoiding losses during drought.

The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during July to November 2016 to investigate the performance of separated tillers of hybrid rice variety Dhani Gold. The experiment comprised three times of tiller transplantation viz. 3, 4 and 5 week aged tiller seedlings and four levels of number of tiller seedlings transplanted hill-1 viz. 2, 3, 4 and 5 tiller seedlings hill-1 laid out in a split plot design with 3 replications. The highest plant height was obtained when 3-week aged tiller seedlings were transplanted at the rate of 3 tiller seedlings hill-1. The highest number of total tillers hill-1 and number of effective tillers hill-1 were found when 3-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The highest grains panicle-1 was obtained when 4-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The highest grain yield was found when 3-week aged tiller seedlings were transplanted with 5 tiller seedlings hill-1. The lowest grain yield was found when 5-week aged tiller seedlings were transplanted with 2 tiller seedlings hill-1 in hybrid rice variety Dhani Gold. Based on the findings of the present study it may be concluded that 3-week old tiller seedlings of Dhani Gold should be transplanted at the rate of 4 or 5 tiller seedlings hill-1 for higher yield. Thus present study confirms the potentiality of growing hybrid rice from separated tillers in case of unavailability of seedlings or to minimize the seed cost of high value hybrid rice seeds. J Bangladesh Agril Univ 17(4): 507–513, 2019

Growing two or more cultivars of same crop species in mixture reduces intra-specific competition for natural resources and increases competitive ability of crops against weeds and thus enhances crop yield. The objective of this study was to evaluate the potentiality of growing rice cultivars in mixtures for minimizing weed pressure and increasing rice yield. The experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during Aman season (July-December) 2017. Two transplant Aman rice cultivars viz. Binadhan-13 (tall, late- maturing and fine grain aromatic cultivar) and BRRI dhan49 (semi-dwarf, mid-maturing and coarse grain cultivar) were grown following two spatial arrangements viz., alternate row and alternate hill, and nine different cultivar mixture (Binadhan-13:BRRI dhan49) row ratios viz., 1:0, 1:2, 2:1, 2:3, 3:2, 2:4, 4:2,1:1 and 0:1. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Results confirmed the positive influence of spatial arrangement and cultivar mixture ratio on rice productivity. Both the cultivars showed better growth and higher yield when grown in mixture irrespective of ratios compared to their sole culture performances. But cultivar mixture ratio showed no advantages over sole culture in suppressing weeds. Based on the total yield Binadhan-13 and BRRI dhan49 inter-planted in 1:1 row ratio following alternate hill performed the best resulting in 50% and 12% yield advantages over sole culture of Binadhan-13 and BRRI dhan49, respectively. Therefore, growing tall and dwarf rice cultivars in mixture can be adopted as a tool for increasing rice productivity. J. Bangladesh Agril. Univ. 17(2): 133–141, June 2019

Parthenium hysterophorus is an invasive weed species that competes aggressively with other plants and is also allelopathic. It poses a significant risk to human health, livestock, the environment, soil, and agriculture. However, given some clinical studies, its potential for antidiabetic, antioxidant, antitumor, herbicidal, pesticidal, and antimalarial therapies should be researched further in attempts to discover more relevant applications. It can be used as a nutrient-dense, readily available, and cheap fertilizer. Parthenium can also be used as an herbicide, an insecticide, and a phyto-remedial mediator to extract metals and dyes from agricultural waste. Here we provide basic information on the morphology, reproduction, environmental impacts, and management of this species. Effects of methanol, ethanol, hexane, acetone, and aqueous (water) Parthenium extracts are described. Because P. hysterophorus is said to be one of the world’s seven worst weeds, some control measures, including mechanical, chemical, cultural, and biological control, are discussed. The allelopathy of this weed is difficult to regulate, and there are both positive and negative interactions between Parthenium and other species due to allelochemical action. Several toxic phenolic compounds produced by P. hysterophorus are responsible for weed suppression, and we discuss details of their mode of action and potential applications.

The current research was conducted to investigate the allelopathic properties of 55 medicinal plant species of Bangladesh representing 32 different families. The aqueous leaves or whole plant extract of those plant species was diluted into four different concentrations viz., 1:5, 1:10, 1:15, 1:20 (w/v) and tested against the seedling growth of Raphanus sativus. A control (distilled water without extract) was also maintained in every cases and the bioassay experiment was replicated thrice. The aqueous extract of all these species inhibited both shoot and root length of R. sativus at concentration greater than 1:15 (w/v) except Delonix regia (Fabaceae) and Leucas aspera (Lamiaceae). The inhibitory activity was concentration dependent and root growth was more sensitive than their shoot. Among the plant species, Citrus aurantifolia (Rotaceae), Moringa oleifera (Moringaceae), Annona muricata (Annonaceae), Aegle marmelos (Rutaceae), Cinnamomum tamala (Lauraceae) and Azadirachta indica (Meliaceae) completely (100%) inhibited the shoot and root growth of R. sativus at concentration 1:5 (w/v). Other than this six plant species, 15 out of 49 medicinal plants showed more than 95% shoot and root growth inhibition at the same concentration. The least allelopathic potential plant was Garcinia mangostana (Clusiaceae) that showed on an average 36% growth inhibition followed by Schleichera oleosa (Sapindaceae). Based on these results it can be concluded that among the tested plant species, C. aurantifolia, M. oleifera, A. muricata, A. marmelos, C. tamala, and A. indica are strongly allelopathic and therefore, could be used as potential candidates for the development of eco-friendly natural herbicides. Keywords: Medicinal plants, Tropical plants, Bio-herbicide, Eco-friendly, Sustainable agriculture

The study was conducted during winter season (February-June) of 2016 at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh. Fourteen rice varieties namely, BRRI dhan28, BRRI dhan29, BRRI dhan47, BRRI dhan50, BRRI dhan55, BRRI dhan58, BRRI dhan59, BRRI dhan67, Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10, BRRI hybriddhan3 and Agrodhan14 were grown under weedy and weed- free conditions. Plots with no rice were also maintained to study the natural growth of weed in absence of rice. Primed rice seeds were dry seeded following 25 cm ×15 cm spacing with 5 seeds hill-1 on non-puddled soil. Plots were surface irrigated as and when necessary to maintain aerobic condition (at around field capacity) up to heading stage followed by wet condition from heading to grain filling stage. The results revealed that rice varieties varied widely in yield performance and weed suppressive ability. Among varieties, BRRI dhan59 allowed the minimum weed growth (20.8 g m-2) while Binadhan-5 allowed the maximum weed growth (65.8 g m-2). Grain yield ranged from 2.2 t ha-1 (BRRI dhan55) to 4.67 t ha-1 (Binadhan-5) under weed-free condition and from 0.62 t ha-1 (BRRI dhan55) to 2.48 t ha-1 (BRRI dhan59) under weedy condition. Weed infected relative yield loss ranged from 40.1% to 78.2% among varieties. BRRI dhan59 incurred the least yield penalty (40.1%) while Binadhan-5 performed the best in terms of grain yield (4.67 t ha-1) but its weed inflicted relative yield loss was higher (76.4%) than any other variety with low yield potential. BRRI dhan59, on the other hand, appeared as the most weed competitive variety (only 40.1% relative yield loss) with yield of 4.19 t ha-1. Present study confirms that the varieties tested under study varied widely in terms of weed suppressive ability and yield performance. Considering both yield and weed competitiveness, BRRI dhan59 can be recommended for cultivation following modified aerobic system.

Weed-competitive rice cultivars, a viable tool for integrated weed management of rice-field weeds, may greatly reduce the weed pressure and excessive dependence on herbicide in controlling weeds. Based on this premise, field experiments were conducted in 2018 and 2019 during the monsoon and winter rice-growing seasons at the Agronomy Field Laboratory of Bangladesh Agricultural University, Bangladesh, to evaluate the weed competitiveness of the selected rice varieties. A total of 42 monsoon and 28 winter rice varieties from Bangladesh were evaluated under “weedy” and “weed-free” conditions in the puddled transplanted system of cultivation. The field experiments were designed with three replications in a randomized complete block design. The results revealed that weed competition greatly reduces the yield of rice, and relative yield loss was 15–68% and 20–50% in monsoon and winter season rice, respectively. The lowest relative yield losses were recorded in monsoon rice from the variety BU dhan 1 (18%) and from the winter rice BRRI hybrid dhan5 (23.7%), which exhibited high weed tolerance. The weed competitive index (WCI) greatly varied among the varieties in both seasons and the monsoon season, ranging from 0.4 to 2.8, and the highest value was recorded from the hybrid variety Dhani Gold followed by BU dhan 1. In winter season rice, the WCI varied 0.25 to 2.4 and the highest value was recorded from the variety BRRI hybrid dhan3, followed by hybrid variety Heera 6. In monsoon rice, hybrid Dhani Gold was the most productive, but BU dhan 1 was the most weed competitive variety. Among the winter-grown varieties, the hybrid Heera 6 was the most productive, and the most weed competitive. Our research confirmed a high degree of variability in weed competitiveness among the 70 Bangladeshi rice varieties tested.

Low seed emergence rate, poor seedling growth and low survival rate of winter rice due to cold spell are very common in Bangladesh. Pre-sowing seed priming could be a viable approach to overcome this problem. A laboratory screening of different priming agents was conducted at the Agro Innovation Laboratory, Department of Agronomy, Bangladesh Agricultural University in November 2018. The experiment comprised two factors. Factor A includes five rice varieties, namely i) BRRI dhan28 ii) BRRI dhan29 iii) BRRI dhan36 iv) BRRI dhan55 and v) Hybrid SL-8H; factor B includes 22 seed priming methods comprised different concentrations of NaCl, KCl CaCl2, CuSO4, ZnSO4, Na2MoO4, PEG and control (no priming). The experiment was laid out in a completely randomized design (CRD) with four replications. A positive influence of seed priming on seed emergence rate (%), germination time, seedling vigor and seedling growth (length and dry matter) was evident from this study. Among the priming agents, KCl and CaCl2 performed best; while priming with NaCl, Na2MoO4 and PEG showed no advantages over no priming for germination rate and seedling vigor & growth indices. In conclusion, pre sowing seed priming approach can be explored as a viable tool for increased seed germination and better seedling growth of winter rice under stress condition.

Aerobic rice or dry direct seeded rice is highly vulnerable to weeds because of lack of “head start” over weeds and standing water layer to suppress weeds. The risks of chemical control and the huge cost involvement in mechanical control demand an eco-friendly and cost-effective integrated weed management. Weed competitive rice cultivar may be considered as a viable tool for integrated weed management. In these circumstances, an experiment was designed to evaluate weed competitiveness of some selected winter rice varieties under aerobic soil conditions. The study was conducted during dry season (February to June) 2016 at the Agronomy Field Laboratory and Weed Management Laboratory, Bangladesh Agricultural University, Mymensingh. Fourteen rice varieties namely, BRRI dhan28, BRRI dhan29, BRRI dhan47, BRRI dhan50, BRRI dhan55, BRRI dhan58, BRRI dhan59, BRRI dhan67, Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10, BRRI hybrid dhan3 and Agrodhan-14 were grown under weedy and weed-free conditions. Plots with no rice were also maintained to observe the natural growth of weed in absence of rice. The experiment was conducted with split-plot design with three replications. Weeding regime was allocated in main plot and rice variety was allocated in sub-plot. Results showed that rice varieties varied widely in their yield performances and weed competitiveness. Among rice varieties, BRRI dhan59 allowed the minimum weed growth (19.2 g m-2) while Binadhan-5 allowed the maximum weed growth (62.8 g m-2). Grain yield ranged from 1.85 t ha-1 (BRRI dhan55) to 3.92 t ha-1 (Binadhan-5) under weed-free condition and between 0.41 t ha-1 (BRRI dhan55) and 2.06 t ha-1 (BRRI dhan59) under weedy condition. Weed inflicted relative yield loss ranged from 43.4% to 82.1% among the varieties. BRRI dhan59 allowed the least yield penalty (43.4%) while Binadhan-5 had the maximum yield penalty (82.1%) due to weed competition. Although Binadhan-5 is the most productive variety (3.92 t ha-1) for aerobic culture but its weed inflicted relative yield loss is higher (82.1%) than many other varieties with low yield potential. On the other hand, BRRI dhan59 appeared as the most weed competitive variety (only 43.4% relative yield loss) with productivity of 3.84 t ha-1. Therefore, weed competitive variety should be considered as a vital tool while designing integrated weed management system for aerobic rice.

On-farm two experiments were carried out at the Fulbaria upazila under Mymensingh district and Agronomy Field Laboratory, Department of Agronomy, Bangladesh Agricultural University (BAU), Mymensingh during the period from November 2011 to March 2012. The experiment comprised ten fields for each of the locations which composed of three weeding regime treatments, namely, unweeded, farmers’ weeded and weed free. The design was randomized complete block with ten replications. Data on weed density, yield contributing characters and yield of wheat were recorded. Except straw yield in Fulbaria all others yield contributing characters were affected significantly due to weeding regime treatment. The highest grain yield was recorded in weed-free treatment compared to farmers weeded and unweeded treatment in Fulbaria. Whereas, in Agronomy Field Laboratory at BAU, the highest grain yield was observed in weed-free treatment which was statistically identical to farmers’ weeded treatment. Five dominant weed species were identified in Fulbaria naimly Cynodon dactylon L. , Cyperus rotundus L. , Alternanthera sessilis L., Polygonum orientale L. and Chenopodium album L. and in Agronomy Field Laboratory at BAU namely Gnaphalium affine L. , Cyperus rotundus L. , Digitaria sanguinalis L., Cynodon dactylon L. and Panicum repens L. Infestation of Cynodon dactylon L. was more in Fulbaria due to control difficulties and Gnaphalium affine L. was more in BAU due to weed seed bank year after year and poor cultural management. So there is scope to increase yield potential of wheat by improving existing weed control practices. Progress. Agric. 2014. 25: 23-30

Aerobic rice is a potential water-wise rice production system, but high weed infestation has threatened its sustainability, which demands an efficient and cost-effective weed management technique. ...

Asystasia gangetica and Pennisetum polystachion are the most troublesome weeds in oil palm plantations in Malaysia and establishment of cover crops under oil palms is an integral part of sustainable weed management in plantations. Replacement-series experiments were conducted to evaluate the mode and strength of competitiveness of four legume cover crop species, Calopogonium caeruleum, Centrosema pubescens, Mucuna bracteata and Pueraria javanica, and one soft grass species, Axonopus compressus, against Asystasia gangetica and Pennisetum polystachion. Relative yield, relative yield total and relative crowding coefficient were calculated with reference to shoot biomass. Asystasia gangetica was a consistently weaker competitor than Pennisetum polystachion. The legume cover crop species had higher relative yield when grown in mixtures, whereas the yield of Asystasia gangetica was lower in mixtures with legumes than in monoculture. The higher competitiveness of legumes was due to greater canopy height...

Growing rice under aerobic soil conditions is a promising water-wise technology under the context of ever-mounting water scarcity, but it is subject to poor stand establishment and high weed pressure. The present study was, therefore, designed to explore the possibility of adopting seed priming as a sustainable tool for weed management in aerobic rice. The trough experiment was established with aerobic rice line Aeron 1 considering four priming techniques: hydropriming, hardening, Zappa® priming and untreated control; and two weeding regimes: weed-free and weedy. Treatments were arranged in a randomized complete block design with four replications. Seed priming significantly improved germination attributes, weed suppressive ability and yield of rice, whilst unprimed control exhibited inconsistent germination, poor stand establishment and less weed competitiveness resulting in poor yield. Seed priming resulted in reduced mean germination time and increased germination percentage, germination index...

Plant density is an important factor affecting soybean seed yield and but information regarding plant density effects on seed quality is highly scarce. The present study examines the relationship of seed yield and quality of two soybean varieties viz., PB-1 and G-2 with plant densities. The experiments were conducted in three consecutive seasons viz., Rabi 2004-05, Kharif 2005 and Rabi 2005-06 at the Agronomy Field Laboratory of Bangladesh Agricultural University, Mymensingh, Bangladesh. Six plant densities viz., 20, 40, 60, 80, 100 and 120 plants m -2 were established using an equidistant planting pattern having spacings of 22.4×22.4 cm, 15.8×15.8 cm, 12.9×12.9 cm, 10.0×10.0 cm and 9.1×9.1 cm, respectively. A split-plot design was used having variety as main plot and density as sub-plot with three replicates. The results revealed that soybean seed yield increased with increase of plant density and the highest yield was obtained at 80 to 100 plants m -2 depending on variety and season. The further increase in plant density reduced the seed yield. The seed yield, seed protein and mineral contents such as phosphorus, calcium, potassium, sulphur and zinc showed a quadratic relation with plant density. Seed protein content decreased with increase in plant density up to 80 or 100 plants m -2 and then increased with further increase in plant density while reverse occurred for seed yield and different minerals. The results also showed that seed protein content was inversely related with seed yield and mineral contents in seed.

Highly diversified tropical tree species could be a potential source of allelopathic compounds, which could lead to development of natural bio-herbicides for sustainable weed management. The present study was therefore designed to investigate into the allelopathic potential of sawdust obtained from eleven tropical tree species available in Bangladesh viz., Azadirachta indica, Swietenia macrophylla, Acacia auriculiformis, Tamarindus indica, Eucalyptus camaldulensis, Syzygium cumini, Mangifera. indica, Albizia. saman, Artocarpus. heterophyllus, Diospyros discolor and Tectona grandis. The aqueous sawdust extract of these plant species were diluted into four different concentrations viz. 1:5, 1:10, 1:15, 1:20 (w/v) and tested for their potentiality in inhibiting seedling growth of allelopathic sensitive plant Raphanus sativus under laboratory condition. A control (distilled water without extract) was also maintained in every cases and the bioassay experiment was replicated thrice. The results of this experiment showed that S. macrophylla, E. camaldulensis, M. indica and A. saman inhibited more than 90% shoot and root growth of R. sativus. The sawdust of these four plant species were selected to evaluate their potentiality in controlling paddy field weeds under filed condition. A total of 16 weed control treatments were considered in the field experiment viz., sawdust of selected four tree plant species at three application rates (1, 2 and 3 t ha-1), manual weeding (three times), chemical control (pre- + post- emergence herbicides), chemical + manual control and season long weedy (control). The results showed that the effect of different sawdust on the weed control varied significantly. Weed growth suppression by the sawdust was increased with the increase in application rate. The results revealed that manual, chemical weed control and application of E. camaldulensis saw dust @ 3 t ha-1 reduced the weed density by 79, 77 and 72%, respectively, and weed biomass by 86, 84 and 79%, respectively. On the other hand, manual weed control offered 100% rice yield increase while, chemical control and E. camaldulensis saw dust @ 3 t ha-1 both resulted in 92% rice yield increase over control. Although, manual and chemical weed control offered higher weed control efficiency and resulted in better rice productivity, but from environmental viewpoint application of E. camaldulensis sawdust @ 3 t ha-1 may be considered for sustainable weed management in rice. [Fundam Appl Agric 2019; 4(3.000): 906-915]

Peat moss (PM) is the most widely used growing substrate for the pot culture. Due to diminishing availability and increasing price of PM, researchers are looking for viable alternatives for peat as a growth media component for potted plants. A pot study was conducted with a view to investigate the possibility of using spent mushroom waste (SMW) for Kai-lan (Brassica oleraceavar. Alboglabra) production replacing peat moss (PM) in growth media. The treatments evaluated were 100% PM (control), 100% SMW, and mixtures of SMW and PM in different ratios like 1 : 1, 1 : 2, and 2 : 1 (v/v) with/without NPK amendment. The experiment was arranged in a completely randomized design with five replications per treatment. Chemical properties like pH and salinity level (EC) of SMW were within the acceptable range of crop production but, nutrient content, especially nitrogen content was not enough to provide sufficient nutrition to plant for normal growth. Only PM (100%) and SMW and PM mixture in 1 : 1 ratio with NPK amendment performed equally in terms of Kai-lan growth. This study confirms the feasibility of replacing PM by SMW up to a maximum of 50% in the growth media and suggests that NPK supplementation from inorganic sources is to ensure a higher productivity of Kai-lan.

Axonopus compressusis one of the native soft grass species in oil palm in Malaysia which can be used as a cover crop. The competitive ability ofA. compressusto overcomeA. gangeticawas studied using multiple-density, multiple-proportion replacements series under a glasshouse and full sunlight conditions in a poly bag for 10 weeks.A. compressusproduced more dry weight and leaf area when competing againstA. gangeticathan in monoculture at both densities in the full sunlight and at high density in the shade. Moreover, the relative yield and relative crowding coefficients also indicatedA. compressusis a stronger competitor thanA. gangeticaat both densities in the full sunlight and high density in the shade. It seemed thatA. gangeticaplants in the shade did not compete with each other and were more competitive againstA. compressusas could influenceA. compressusheight in the shade. It is concluded that although suppression ofA. gangeticabyA. compressusoccurred under full sunlight, irrespective of plant density, this ability reduced under shade asA. compressusdensity decreased. The result suggests thatA. compressusin high density could be considered as a candidate for cover crops under oil palm canopy.

This study investigated the allelopathic effect ofAxonopus compressuslitter onAsystasia gangeticaandPennisetum polystachion. In experiment 1 the bioassays with 0, 10, 30, and 50 g L−1of aqueousA. compressuslitter leachate were conducted. Experiment 2 was carried out by incorporating 0, 10, 20, 30, 40, and 50 g L−1ofA. compressuslitter leachate into soil. In experiment 3, the fate ofA. compressuslitter leachate phenolics in the soil was investigated.A. compressusleachates did not affect the germination percentage ofA. gangeticaandP. polystachion, but delayed germination ofA. gangeticaseeds and decreased seed germination time ofP. polystachion.A. compressuslitter leachates affected weeds hypocotyl length. Hypocotyl length reductions of 18 and 31% were observed at the highest concentration (50 g L−1) compared to the control inA. gangeticaandP. polystachion, respectively. When concentration ofA. compressuslitter leachate-amended soil increasedA. gangeticaandP. polystachionseedling shoot length, root length, seedling weight and chlorophyll concentration were not affected. The 5-week decomposition study ofA. compressusshowed that the phenolic compounds inA. compressuslitter abruptly decreased about 52% after two weeks and remained steady until the end of the incubation.