Effect of inoculum concentration, wetness duration and plant age on disease development by Exserohilum prolatum in itchgrass (Rottboellia cochinchinensis)

Exserohilum prolatum, a fungus isolated from diseased itchgrass plants in Peninsular Malaysia, has been considered as a potential agent for biological control of this serious grass weed. Inoculum concentration, wetness duration and itchgrass age significantly influenced disease development by E. prolatum in itchgrass when evaluated in glasshouse experiments. Disease development increased with increasing inoculum concentration from 2x104 to 2x107 conidia/ml. As wetness duration increased, disease development increased. Complete kill of itchgrass at 3 to 4 leaf stage was obtained at 2x106 conidia/ml and a 24 hr dew period. However, when formulated in 0.01% Tween 20 and 2% palm oil, E. prolatum reduced wetness duration requirement, and exposure to 12 hr dew period resulted in 80% reduction in itchgrass shoot dry weight. Susceptibility of itchgrass to the fungus decreased with increasing plant age. Itchgrass at two to six leaf stages were the most susceptible to fungus infection. يعتبر فطر(Exserohilum prolatum)  والذي تم عزله من عشبة أم بليلة في شبه جزيرة ماليزيا وسيلة مكافحة إحيائية فاعلة لهذه العشبة النجيلية الضارة. عوامل تركيز اللقاح ، فترة الرطوبة وعمر النبات أثرت معنوياً على تطور المرض بواسطة (E. prolatum) في عشبة أم بليلة عندما قيّمت بتجارب داخل صوبة زجاجية. وقد تلاحظ أن تطور المرض قد إرتفع إرتفاعاً معنوياً مع إرتفاع معدل تركيز اللقاح منx 2  104 وإلى 2 x 107 كونيديا/مل. من ناحية أخرى تلاحظ أن شدة الإصابة بالمرض إزدادات معنوياً بإزدياد فترة الرطوبة. هذا وقد حدت موت كلي للعشبة عمر 2-3 ورقات عندما تمت معاملتها بواسطة تركيز لقاح 2x106 كونيديا/مل وفترة رطوبة 24 ساعة. أدى إستخدام عامل إنتشار Tween 20 بنسبة 0.01% وزيت النخيل بنسبة 2% إلى تقليص الحاجة إلى فترة رطوبة ممتدة (24 ساعة) حيث إنخفض الوزن الجاف للمجموع الخضري بنسبة 80% عند معاملة العشبة بفترة رطوبة بلغت 12 ساعة. أبانت النتائج أن قابلية العشبة للإصابة بالفطر قد إنخفضت مع تقدم عمر النبات وأن الأعشاب عمر 2-6 ورقات كانت أكثر قابلية للإصابة

Influence of biofertilizer on growth improvement of aerobic rice genotypes

Biofertilizers have emerged as a potential environment friendly inputs that are supplemented for proper plant growth.Two field experiments were conductedat University Putra Malaysia (UPM), Selangor, Malaysia during 1st season (Mayto September 2015) and 2nd season (September to December 2015)to evaluate the performance of aerobic rice genotypes under different combinations of bioandchemical fertilizer. The experiment consisted of five (5)biofertilizer combinations (chemical fertilizer recommended rate (CFRR) (150 N; 60 P2O5;60 K2O kg ha-1) 100%,biofertilizer 1 ton+ 75%CFRR,biofertilizer 2 tons + 50%CFRR,biofertilizer 3tons+ 25%CFRR,and biofertilizer 4 tons)and three aerobic rice genotypes (MRIA1, MR219-4 and MR219-9)laid out in a split-plot in randomized complete block design(RCBD) with 3 replicates.Results revealed that application of biofertilizer 1 ton + 75%CFRR produced the highest plant height (102.65 cm) and an umberof tillers (20.38) in the 2nd season, the highest grain yield (4.30 t ha-1) than theother biofertilizer treatments in the 1st season. MR219-4 produced the highest number of tillers, leaf area and leaf photosynthesis rate in both seasons,grain yield (5.02 t ha-1) in 1st season while MR219-9 produced the highestcropbiomass (52.76 g hill-1) and crop growth rate (8.00 g hill-1week-1) at 12 WAS,grain yield (3.86 tha-1) than the other genotypes in the 2nd season.The trend in these results indicated that biofertilizer tend to be more effective with limited chemical fertilizer in the 1st season of low rainfall.These results concluded that 1 ton biofertilizer + 75% CFRR andMR219-4enhancesrice growth and grain yield in aerobic condition

Echinochloa crus-galli (L.) P. Beauv

Echinochloa crus-galli (L.) P. Beauv., a C4 annual grass, is locally known in Malaysia as Rumput Sambau and in English as Barnyardgrass. E. crusgalli was included in the Global Compendium of Weeds and is considered one of the world’s worst weeds (Randall, 2017) in rice and earlier it was also listed as a weed in at least 36 other crops in 61 countries throughout tropical and temperate regions of the world (Holm et al., 1991). E. crusgalli is also considered an environmental weed that has become invasive in natural grasslands, coastal forests and disturbed sites in Asia, Africa, Australia, Europe and America (FAO, 2014; USDA-ARS, 2014). In Malaysia, it was detected in 1925 (NWGIAS, 2014) and suspected to be introduced unintentionally through contaminated seeds (Moody, 1989). Since then, the weed has spread and becomes the most important weed in all rice growing areas. Ministry of Natural Resources and Environment (2009), Malaysia has included E. crus-galli as one of the Invasive Alien Species (IAS) that affects all sectors such as agriculture, forestry, fishery, marine and animals. In Malaysia, the adoption of double cropping and more rapidly maturing cultivars in rice cultivation and a shift from transplanting to direct- seeding has resulted in grasses such as E. crus-galli, largely replacing the previously dominant broadleaved weeds and sedges (Ho & ZuM, 1988). The limited success in the suppression of E. crus-galli is a concern (Begum et al., 2005,2005a). In this paper synthesized information is included on the ecology, current scenario of infestation, losses caused and management of E. crus-galli in Malaysia..

Allelopathic Potential of Rice Varieties against Spinach (Spinacia oleracea)

Two laboratory experiments were conducted to investigate the allelopathic effects of rice varieties on spinach (Spinacia aleracea L.). Fifteen rice varieties were included for evaluation. Two methods viz. Sandwich method and Relay seeding method were used to observe the allelopathic effects of rice varieties on seed germination, mean germination time, shoot and root length and dry matter production of spinach as a test crop. Average inhibition in spinach growth was calculated to evaluate the allelopathic potential of the rice varieties. All the selected varieties of rice were more or less detrimental to studied characters of spinach. WITA12 resulted in about 48% average percent inhibition of spinach growth. On the basis of average percent inhibition rice varieties ranked in order of WITA12>Dular>WITA3>BR26>BRRI dhan42>BRRI dhan39>BRRI dhan31>BRRI dhan44>BRRI dhan40>BR19>BRRI dhan43>BRRI dhan46>BRRI dhan47>BRRI dhan45>BRRI dhan28. Both the evaluation methods were positively correlated in determining percent reduction in most of the parameters of spinach due to allelopathic effects of rice

Toxicity assessment of groundwater quality in Bangladesh.

A study was conducted to assess long-term effect of ground water for irrigation at Chirirbandar upazila, 25 kilometers eastern from Dinajpur district in from February to April in 2006. All the waters were analyzed and classified into different categories for their suitability as irrigation, drinking and industrial usage. The chemical analyses were included pH, EC, TDS, Ca, Mg, Na, K, Fe, Cu, Mn, Zn, B, As, SO4, P, HCO3 and Cl. The SAR, SSP, RSC and HT were calculated for the research. The pH (6.55 to 7.75) showed slightly acidic to slightly alkaline. The TDS was rated as ‘fresh water’, EC and SAR were ‘medium’ (C2 ) class and ‘low alkali hazard’ (SI) class which jointly expressed as C3S1. The study was found that SSP was in ‘excellent’ category. Waters were free from RSC and belonged to ‘suitable’ category for irrigation. The waters were classified as ‘hard’ and ‘very hard’ based on hardness (HT). It was found that both Fe and Mn content of all samples were not having problem for industrial usage. Boron was identified as ‘suitable’ for drinking consumption and sulphate was ‘suitable’ for drinking and industrial usage. The relationship of pH vs. EC, pH vs. TDS, EC vs. TDS, EC vs. HT, TDS vs. HT, SAR vs. SSP, SAR vs. RSC, and SSP vs. RSC indicated significant positive correlation. Among the quality determining factors SSP and SAR were highly correlated where correlation coefficient was 0.964

Seedbank and Seedling Emergence Characteristics of Weeds in Ricefield Soils of the Muda Granary Area in North-west Peninsular Malaysia

Tlie experiment was conducted in the glasshouse of UPM from March 2003 to June 2004 to determine the soil seedbank in the ricefields ot\u27Muda rice granary area in Peninsular Malaysia. Six soil cores of 5 cm in diameter and 10 cm depth were sampled from each of 24 fields. All samples from each individual field were bulked and placed in plastic trays of 38 x 25 x 10 cm. Soil was moistened as required and emergence of weed seedlings were recorded over period of one year. After one year, remaining seeds were separated, removed and identified. The total seed bank was estimated at 1136.48 million/ha of which 62.35% (708.60 million seedlings ha"1) germinated within 12 months and 37.65% (427.88 million seeds ha"1) remained ungerminated. Total of 20 taxa were recognized. Based on importance value (I.V.) the five most dominant species in terms of emerged seedling were Fimbristylis miliacea, Leplochloa chinensis, LitJwigia hyssopifolia, Cyperus difformii and C. iria. Of the remaining seeds the five dominant species with decreasing trend in ranking were F. miliacea, Scirpus lateriflonis, Monochoria vagina/is, L. hyssopifolia and L. chinensis. Ranking of total seed reserves (seedlings+ remaining seeds) were similar to emerged seedling indicating that emerged seedlings reflect the actual weed flora in the Muda area. Among the dominant species F. miliacea accounted for 58.07% of emerged seedlings, 79.31% of remaining seeds and 66.07% of total seed bank. Total seedling emergence of all species was higher in the first observation in April 2003 and cumulative seedling emergence showed no clear peaks