Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

Seed dispersal into wetlands: techniques and results for a restored tidal freshwater marsh

Abstract: Although seed dispersal is assumed to be a major factor determining plant community development in restored wetlands, little research exists on density and species richness of seed available through dispersal in these systems. We measured composition and seed dispersal rates at a restored tidal freshwater marsh in Washington, DC, USA by collecting seed dispersing through water and wind. Seed dispersal by water was measured using two methods of seed collection: (1) stationary traps composed of coconut fiber mat along an elevation gradient bracketing the tidal range and (2) a floating surface trawl net attached to a boat. To estimate wind dispersal rates, we collected seed from stationary traps composed of coconut fiber mat positioned above marsh vegetation. We also collected a small number of samples of debris deposited along high tide lines (drift lines) and feces of Canada Goose to explore their seed content. We used the seedling emergence method to determine seed density in all samples, which involved placing the fiber mats or sample material on top of potting soil in a greenhouse misting room and enumerating emerging seedlings. Seedlings from a total of 125 plant species emerged, during this study (including 82 in river trawls, 89 in stationary water traps, 21 in drift lines, 39 in wind traps, and 10 in goose feces). The most abundant taxa includedBidens frondosa, Boehmeria cylindrica, Cyperus spp.,Eclipta prostrata, andLudwigia palustris. Total seedling density was significantly greater for the stationary water traps (212±30.6 seeds/m2/month) than the equal-sized stationary wind traps (18±6.0 seeds/m2/month). Lower-bound estimates of total species richness based on the non-parametric Chao 2 asymptotic estimators were greater for seeds in water (106±1.4 for stationary water traps and 104±5.5 for trawl samples) than for wind (54±6.4). Our results indicate that water is the primary source of seeds dispersing to the site and that a species-rich pool of dispersing propagules is present, an interesting result given the urbanized nature of the surrounding landscape. However, species composition of dispersing seeds differed from vegetation of restored and natural tidal freshwater marshes, indicating that planting is necessary for certain species. At other restoration sites, information on densities of dispersing seeds can support decisions on which species to plant.

Tillage and Residue Effects on Wheat, Sorghum, and Sunflower Grown in Rotation1

Abstract: Tillage methods affect soil surface conditions and amounts of crop residue retained on the soil surface, which, in turn, affect water infiltration and subsequent evaporation. The objectives of this study were to determine the effect of tillage methods and wheat residue levels on soil water storage and use, and on crop growth and yields. The study, conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls), involved an irrigated winter wheat (Triticum aestivum L.)-dryland grain sorghum [Sorghum bicolor (L.) Moench]-dryland sunflower (Helianthus annuus L.) cropping system. A 330-d fallow period occurred between wheat harvest and sorghum planting and a 210- to 270-d fallow period (overwinter) occurred between sorghum harvest and sunflower planting. Wheat was planted 30 to 60 d after sunflower harvest. After wheat harvest, residues were partially removed from one-half of the plots; residues on the other half were not removed. Then, moldboard-, disk-, rotary-, sweep-, and no-tillage treatments were applied. Soil water content increases during fallow after wheat averaged 89, 109, 85, 114, and 141 mm for the respective tillage treatments, and averaged 97 and 118 mm for the low and high residue treatments. Precipitation averaged 316 mm during fallow. The differences in stored water significantly affected sorghum growth; grain and forage yields; and seed test weight, weight/seed, and protein. Sorghum grain yields averaged 2.56, 2.37, 2.19, 2.77, and 3.34 Mg/ha with the respective tillage treatments. The tillage treatments had no residual effect on subsequent sunflower and wheat yields. However, including sunflower in the rotation apparently allowed extraction of water from deeper in the profile than that extracted by sorghum, thus increasing the utilization of water resources for crop production. In addition, the earlier harvest date for sunflower allowed wheat to be planted at a more optimum time than that which is possible when wheat is planted after grain sorghum harvest

Influence of sowing density and spatial pattern of spring wheat (Triticum aestivum) on the suppression of different weed species

Abstract: To better understand the potential for improving weed management in cereal crops with increased crop density and spatial uniformity, we conducted field experiments over two years with spring wheat (Tr iticum aestivum) and four weed species: lambsquarters (Chenopodium album), Italian ryegrass (Lolium multiflorum), white mustard (Sinapis alba), and chickweed (Stellaria media). The crops were sown at three densities (204, 449, and 721 seeds m −2 ) and in two spatial patterns (normal rows and a highly uniform pattern), and the weeds were sown in a random pattern at a high density. In most cases, the sown weeds dominated the weed community but, in other cases, naturally occurring weeds were also important. There were strong and significant effects regarding the weed species sown, the crop density, and the spatial distribution on the weed biomass in both years. The weed biomass decreased with increased crop density in 29 out of 30 cases. On average, the weed biomass was lower and the grain yield was higher in the uniform compared to the row pattern in both 2001 and 2002. Despite the differences in weed biomass, the responses of L. multiflorum, S. media, and C. album populations to crop density and spatial uniformity were very similar, as were their effects on the grain yield. Sinapis alba was by far the strongest competitor and it responded somewhat differently. Our results suggest that a combination of increased crop density and a more uniform spatial pattern can contribute to a reduction in weed biomass and yield loss, but the effects are smaller if the weeds are taller than the crop when crop‐weed competition becomes intense.

Rice Seed Invigoration: A Review

Abstract: Rice (Oryza sativa L.) provides about 55–80% of the total calories for people in South Asia, Southeast Asia, and Latin America. Elsewhere, it represents a high-value commodity crop. Change in the method of crop establishment from traditional manual transplantation of seedlings to direct seeding has been adopted in many Asian countries in the last two decades, in view of rising production costs, especially for labor and water. Seed invigoration is ascribed to beneficial treatments, applied to the seeds after harvest but prior to sowing, that improve germination or seedling growth or facilitate the delivery of seeds and other materials required at the time of sowing. Many seed invigoration treatments are being employed in a number of field crops, including rice, to improve seedling establishment under normal and stressful conditions. The treatments used to invigorate rice seed include hydropriming, seed hardening, on-farm priming, osmopriming, osmohardening, humidification, matripriming, priming with plant growth regulators, polyamines, ascorbate, salicylicate, ethanol, osmolytes, coating technologies, and more recently presowing dry heat treatments. In the wake of the day-to-day increasing cost of labor and shortage of water, direct seeding approaches in rice cropping systems are the subject of intensive investigation throughout the world and offer an attractive alternative to traditional rice production systems. In this regard, seed invigoration techniques are pragmatic approaches to achieving proper stand establishment in the new rice culture. They help in breaking dormancy and improving seedling density per unit area under optimal and adverse soil conditions. Induction and de novo synthesis of hydrolases, such as amylases, lipases, proteases; and antioxidants such as catalases, superoxide dismutase and peroxidases are reported to be the basis of improved performance using these techniques. The rice seed priming can be performed by soaking simply in water, a solution of salts, hormones, osmoprotectants, matric strain-producing materials, and other nonconventional means. Despite certain limitations, such as water potential, oxygen and temperature, rice seed invigoration has been worthwhile in improving rice yield and quality. Nevertheless, in-depth studies are imperative for understanding the physiological and molecular basis of rice seed priming.

Influence of potassium fertilization and foliar application of zinc and phosphorus on growth, yield components, yield and fiber properties of Egyptian cotton (Gossypium barbadense L.)

Abstract: Aims Supplying optimal quantities of mineral nutrients to growing crop plants is one way to improve crop yields. Nutrients need to be used rationally in order to avoid a negative ecological impact and undesirable effects on the sustainability of agricultural production systems. Excessive application of nutrients also affects the farmer’s economy. In order to calculate the amount of fertilizer to be applied to crops, it is necessary to develop recommendation programmers that adjust nutrient rates to crop requirements. Methods Experiments in two successive seasons were conducted to investigate the effect of K fertilization and foliar application of Zn and P on yield and fiber properties of cotton cv. Giza 86. Potassium (0.0 and 47.4 kg of K ha ) was soil applied, while chelated zinc (0.0 and 57.6 g of Zn ha , applied twice at 70 and 85 days after sowing ‘DAS’) and phosphorus (0.0, 576, 1 152 and 1 728 g of P ha , applied twice at 80 and 95 DAS) were applied to the foliage. Important findings Dry matter yield, total chlorophyll concentration, K, Zn and P uptake per plant, number of opened bolls per plant, boll weight, seed index, lint index, seed cotton yield per plant, seed cotton and lint yield ha 1 and earliness of harvest increased with the application of K, Zn and P. Treatments generally had no significant effect on lint percentage and fiber properties, with exceptions, for micronaire reading and flat bundle strength, and uniformity ratio, where the mean values of these characters were significantly increased over the untreated control by applying K, and for the micronaire reading in the first season, when applying P at 1 728 g ha , and uniformity ratio in the second season, when applying Pat 1 152 and 1 728 g ha , where the mean values of these characters were significantly increased over the untreated control by applying P. Under the conditions of this study, applying K fertilization at 47.4 kg ha 1 combined with spraying cotton plants with zinc at 57.6 g ha 1 and also with P at 1 728 g ha 1 improved growth and yield of Egyptian cotton.