[Show abstract][Hide abstract] ABSTRACT: Field studies were carried out to evaluate the influence of allelopathic plant water extracts applied alone or tank-mixed with a reduced herbicide dose on the weeds of wheat. Water extracts of sorghum (Sorghum bicolor (L.) Moench.) + sunflower (Helianthus annuus L.) + mulberry (Morus alba L.) were used alone (each at 20 L ha(-1)) or combined with iodo + mesosulfuron (3.6 and 7.2 g active ingredient (a.i.) ha(-1); 25 and 50% of the recommended dose, respectively). The recommended dose of herbicide, a weedy check and a weed-free treatment were included for comparison. Allelopathic water extracts alone suppressed the density of canary grass (Phalaris minor Retz.) and wild oat (Avena fatua L.) by 34-42%, and dry weight by 59-67%. The mixture of allelopathic plant water extracts combined with reduced doses of iodo + mesosulfuron gave weed control equal to the recommended dose of the herbicide. Integration of plant water extracts with reduced herbicide rates provide effective weed control and a wheat yield comparable to using the recommended herbicide dose.
[Show abstract][Hide abstract] ABSTRACT: Allelopathy is a naturally occurring ecological phenomenon of interference among organisms that may be employed for managing weeds, insect pests and diseases in field crops. In field crops, allelopathy can be used following rotation, using cover crops, mulching and plant extracts for natural pest management. Application of allelopathic plant extracts can effectively control weeds and insect pests. However, mixtures of allelopathic water extracts are more effective than the application of single-plant extract in this regard. Combined application of allelopathic extract and reduced herbicide dose (up to half the standard dose) give as much weed control as the standard herbicide dose in several field crops. Lower doses of herbicides may help to reduce the development of herbicide resistance in weed ecotypes. Allelopathy thus offers an attractive environmentally friendly alternative to pesticides in agricultural pest management. In this review, application of allelopathy for natural pest management, particularly in small-farm intensive agricultural systems, is discussed.
[Show abstract][Hide abstract] ABSTRACT: Effects of organic manures on grain yield and yield components of wheat (Triticum aestivum L.) cultivar Bhakar-2002 were studied at adoptive research farm Karor, Layyah during 2006 to 2007 season. In the present study five organic manures; green manure (GM), farm yard manure (FYM), poultry litter (PL), press mud (PM) and sewage sludge (SS) were evaluated. Six treatments were established by different combinations of these manures. A treatment with recommended NPK was also maintained. Results indicated that maximum weed density (63.50 m -2) having high dry weight (13.53 g m -2) was found where GM+FYM+PM each @ of 10 t ha -1 was used while minimum weed density (42.75 m -2) and dry weight (1.53 g m -2) of weeds were observed where weeds were controlled chemically. Combination of PL+SS each @ 10 t ha -1 with GM (T 6) gave maximum productive tillers, number of grains per spike (48.25), thousand grain weight (37.23 g), economic yield (3.10 t ha -1) and harvest index (39.28%) while in recommended NPK treatment, the productive tillers (189.8), biological yield and harvest index was at par with T 6 . The combination of GM, FYM and PM gave minimum number of grain per spike (34.25), grain yield (1.95 t ha -1) and harvest index (31.40%). Economic analysis showed that the combination of PL, SS and GM gave maximum net benefit (Rs. 38040) with high marginal rate of return (4032%) while minimum net benefit (Rs. 21912) was found where GM, FYM and PM was used. However in marginal analysis, all other treatments were dominated due to less benefit than preceding treatments.
[Show abstract][Hide abstract] ABSTRACT: In a field study, the growth, grain yield and economic traits were studied under different intercropping systems in direct seeded rice under strip plantation at the University of Agriculture, Faisalabad for two consecutive years. The intercropping systems comprised rice alone, rice + maize, rice + sesbania, rice + mungbean, rice + ricebean, rice + cowpea and rice + pigeonpea. Rice was seeded in 75 cm spaced 4-row strips (15/75 cm), while the intercrops as forage were seeded on the vacant spaces between the rice strips. The results revealed that dry matter of rice was decreased substantially due to intercropping of different forage legumes and non-legumes as compared to sole cropping of rice. Rice growth was more suppressed with a sesbania companion crop than with maize because of relatively thick shading effect of sesbania due to its vigorous vegetative growth rate. The results also revealed that rice grain yield was decreased to a significant level by forage intercrops compared to monocropped rice, which varied from 10.94 to 25.87%, with the maximum (25.87%) by sesbania against the minimum (10.94%) by maize intercrop. Among the intercrops, maize grown in association with rice produced significantly the highest forage yield (40.70 t ha -1). In terms of total rice grain yield equivalent (TRGYE), the highest TRGYE (6.45 t ha -1) was recorded for rice + forage maize intercropping system. Similarly the net field benefits obtained from different intercropping systems were considerably higher than the sole cropping of rice. The maximum net benefit of Rs. 42325 ha -1 was recorded for rice + maize, which is 37.32% more than sole rice. The dominance analysis showed that rice + maize, rice + cowpea and rice+pigeonpea intercropping systems are more profitable than growing rice alone and other intercropping systems. According to marginal rate of return, the highest MMR (2244%) was realized from rice + forage maize intercropping system followed by rice+cowpea (158%) against rice alone. It was also inferred from all sensitivity analysis options that rice+maize and rice+cowpea intercropping systems were economical and viable against sole rice.
[Show abstract][Hide abstract] ABSTRACT: The carry-over effect of sub-lethal herbicides was investigated on the germination of seeds collected from surviving Chenopodium album plants, which had received 1/8, 1/8 twice, 1/8 three times, 1/4, 1/2, 1/1 doses of either pre-emergence ioxynil or post-emergence bentazone in a previous onion (Allium cepa) crop. Seeds were also collected from surviving C. album plants, which had received 1/4, 1/2, 1/1 of either pre-emergence pendimethalin, propachlor and linuron, or 1/8, 1/8 twice, 1/8 three times, 1/4, 1/2, 1/1 of post-emergence ioxynil or linuron in a previous leek (Allium porrum) crop. Seeds of surviving plants were collected and tested for germination at temperature of 5, 10, 15, 20 and 25 degrees C. The effect of different temperatures on the total number of germinated seeds was significant. Germination was minimum at low temperatures (5 degrees C or 10 degrees C). Herbicides did not show any effect on germination of C. album and resulted in the same final germination percentage as seeds collected from the unsprayed control plots.
Anais da Academia Brasileira de Ciências 12/2009; 81(4):873-9.
[Show abstract][Hide abstract] ABSTRACT: Water extracts obtained from the roots, shoots, and fruits of mature wild onion (Asphodelus tenuifolius) plants and soil taken from an A. tenuifolius field were used to determine their allelopathic effects on the germination and seedling growth of chickpea (Cicer arietinum) in the laboratory. The roots, shoots, and fruits of A. tenuifolius were soaked individually in water in a ratio of 1:20 (w/v) for 24 h to prepare the extracts. Distilled water was used as the control. The germinated seeds were taken out from the Petri dishes and counted every day for 12 days. The seeds of chickpea were also sown in sand and in each of the controlled, normal soil and the soil taken from the A. tenuifolius-infested field in Petri dishes to record the length and weight of the roots and shoots 18 days after sowing. The mean germination time reached the maximum amount for the stem and fruit extracts. The fruit extract caused the most reduction in the germination index and the germination percentage of chickpea. The different wild onion organ extracts significantly reduced the root and shoot length and biomass of the chickpea seedlings compared with the distilled water. The fruit extract of wild onion proved to be the most detrimental to the root length, shoot length, and dry weight of the chickpea seedlings. The soil beneath the A. tenuifolius plants significantly reduced the emergence, root length, shoot length, shoot dry weight, and seedling dry weight but increased the root dry weight of the chickpea seedlings. It is suggested that A. tenuifolius releases phytotoxic compound(s).
Weed Biology and Management 05/2009; 9(2):146 - 151.
[Show abstract][Hide abstract] ABSTRACT: Phosphorus accounts for one of the largest energy inputs in canola production. Understanding the effects of phosphorus on yield and oil quality of canola will help in increasing its chances to better fit in the present cropping systems of Pakistan. This study determined the response of canola hybrids to different sources of phosphatic fertilizers. Two canola hybrids, namely Hyola-43 and Hyola-401 were grown using four different sources of phosphorus (MAP, DAP, NP, SSP) during 2004-05 and 2005-06. Canola hybrids differed significantly for all the yield and oil quality traits during both years of study. Hyola-43 resulted in 6.7 and 13.4% increase in seed yield over Hyola-401 during 2004-05 and 2005-06, respectively. Hyola-43 also produced significantly higher values of oil and protein content over Hyola-401. Increase in oil and protein content varied from 3.3-5.5% and 5.0-5.1% in 2004-05 and 2005-06, respectively. Differences in seed yield, yield parameters and oil quality were non-significant in response to phosphatic fertilizers.
[Show abstract][Hide abstract] ABSTRACT: Water stress is a major limiting factor for sunflower production in the arid and semi arid regions in the world. A field experiment was conducted to assess the impact of different planting pattern and irrigation levels on growth and yield of spring planted sunflower. Four planting patterns (P 1 = 60 cm spaced single row flat sowing, P 2 = 60 cm spaced single row ridge sowing, P 3 = 90 cm spaced double row strip flat sowing, P 4 = 90 cm spaced double row bed sowing) and four irrigation levels (I 0 = normal irrigations, I 1 = irrigation skipped at pre-anthesis stage, I 2 = irrigation skipped at anthesis stage, I 3 = irrigation skipped at post-anthesis stage) were used. Maximum LAI and CGR were recorded at P 2 , whereas post anthesis stress treatment produced maximum crop growth. Maximum value of NAR was observed at P 3 treatment and at anthesis stress. Highest achene yield (kg ha -1) was recorded at P 2 I 0 (38% more yield than P 3 I 1) treatment.
[Show abstract][Hide abstract] ABSTRACT: As maize is a chilling-sensitive crop, low temperatures during the early stages of development can be injurious to crop growth and development. Prime mechanism behind chilling-induced damage is oxidative stress. This study was undertaken to improve the chilling tolerance in hybrid maize by seed priming with KCl. For priming, seeds of the maize hybrid Hycorn 8288 were soaked in 50, 100 and 150 mg l−1 aerated solution of KCl for 24 h and then re-dried close to original weight. Primed and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Seed priming improved the performance of maize under both normal and stress conditions. It was found that the chilling tolerance in maize is well associated with the enhanced capacity of the anti-oxidative system. Priming with KCl significantly improved the chilling tolerance mainly by the activation of antioxidants including catalase, superoxide dismutase and ascorbate peroxidase enzymes. KCl treatments also improved the germination rate and time, root and shoot length, and fresh and dry weights of seedlings compared with control. Soluble sugars and α-amylase activity determined as general metabolic indicators of stress were also improved by seed priming with KCl. Other possible bases of chilling tolerance in maize included maintenance of high tissue water contents, reduced electrolyte leakage and carbohydrate metabolism. Seed treatment with 100 mg l−1 KCl was the best treatment to improve the performance of hybrid maize both under normal and chilling stress conditions.
Journal of Agronomy and Crop Science 09/2008; 194(6):438 - 448.
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