PEMBERIAN PAKAN ALAMI BERBEDA UNTUK MENINGKATKAN PERTUMBUHAN DAN KELANGSUNGAN HIDUP BENIH IKAN NILA SULTANA OREOCHROMIS NILOTICUS

Pakan alami merupakan pakan yang paling sesuai digunakan sebagai pakan benih ikan yang mendukung pertumbuhan dan kelangsungan hidup benih ikan . Penelitian ini bertujuan untuk mengetahui pemberian pakan alami (Dapnia sp, Tubifex sp, Cacing Darah) terhadap pertumbuhan dan kelangsungan hidup benih ikan nila Sultana. Metode yang digunakan dalam penelitian adalah rancangan acap lengkap (RAL) dengan tiga perlakuan dan tiga kali ulangan : Daphnia sp. Tubifex sp. dan Cacing Darah. Peningkatan Pertumbuhan Benih ikan nila selama 35 hari pemeliharaan menunjukkan peningkatan berat tertinggi terdapat pada perlakuan Tubifex sp, dari 8,6 menjadi 16,0 gr, selanjutnya diikuti pada perlakuan Cacing Darah dari 8,47 menjadi 9,36 gr, dan berat terendah terdapat pada perlakuan Daphnia sp dari 7,97 menjadi 8,7 gr. Tingkat kelangsungan hidup Benih tertinggi terdapat pada perlakuan Tubifex sp sebesar 83%, kemudian Cacing Darah 68%, dan terendah pada perlakuan Daphnia sp 65%. Pengaruh pemberian pakan alami tidak berpegaruh nyata terhadap pertumbuhan spesifik, sedangkan kelangsungan hidup Ikan Nila Sultana berpengaruh nyata. Natural feed is the most suitable feed used as fish seed feed that supports the growth and survival rate of fish fry. This study aims to determine the provision of natural food (Dapnia sp, Tubifex sp, Blood Worm) on the growth and survival rate of Sultana tilapia fry. The method used in this study was a randomized complete design (CRD) with three treatments and three replications: Daphnia sp. Tubifex sp. and Blood Worms. The increase in the growth of tilapia seeds during 35 days of rearing showed the highest increase in weight was found in the Tubifex sp treatment, from 8.6 to 16.0 g, followed by the Bloodworm treatment from 8.47 to 9.36 g, and the lowest weight was found in Daphnia sp treatment from 7.97 to 8.7 gr. The highest seed survival rate was found in the treatment of Tubifex sp by 83%, then Bloodworms 68%, and the lowest in the treatment of Daphnia sp 65%. The effect of natural feeding had no significant effect on specific growth, while the survival of Tilapia Sultana had a significant effect.

Cyclone “Seed” Survival Affects Hurricane Season Intensity

Understanding how seed storms grow into full-blown hurricanes and typhoons could help predict hurricane season intensity in a changing climate.

Burial Environment Drives Seed Mortality of Kochia (Bassia scoparia), Wild Oat (Avena fatua), and Volunteer Canola (Brassica napus) Irrespective of Crop Species

Models of weed population demography are critical to understanding the long-term viability of management strategies. The driving factors of weed seedbank persistence are often underrepresented in demographic models due to the cumbersome nature of seedbank research. Simplification of weed seedbank dynamics may induce substantial error in model simulations. A soil bioassay was conducted to determine whether growth of different crop species, including wheat (Triticum aestivum L.), canola (Brassica napus L.), and field pea (Pisum sativum L.), differentially impact seed mortality of kochia [Bassia scoparia (L.) A.J. Scott], wild oat (Avena fatua L.), and volunteer canola in seven burial environments in western Canada. Weed seed survival after the 7 week burial period varied widely among burial environments (from 8% to 88% when averaged among weed and crop species), whereas growth of the different crop species had negligible impact on seedbank persistence. Among environments, wild oat seed survived the greatest (79%), followed by kochia (20%), and volunteer canola (6%). Weed seed survival was associated with soil physical properties (texture) and seed microsite characteristics (temperature), but not crop species or soil chemical properties. Overall, these data support the need for greater integration of soil and environmental parameters into models of weed population demography.

Seed longevity of two nutrient-dense vegetables (Amaranthus spp.)

For many traditional vegetables, seed longevity is unknown, limiting proper seed bank management. In this study, the comparative seed longevity of two nutrient-dense leafy vegetables, blood amaranth (Amaranthus cruentus) and edible amaranth (A. tricolor), was compared together with two reference crops, crookneck squash (Cucurbita moschata) and soya bean (Glycine max). Seed lots of four genebank accessions of the corresponding vegetable species were treated under accelerated ageing (AA) conditions with an average of 41.1°C and an average of 89.9% relative humidity for 33 days to generate single seed survival curves and calculate the time taken for seed viability to fall to 50% (p50). The seed survival curves of all four species had values of goodness to fit (R2) values between 0.43 and 0.85. Seeds of the A. cruentus and A. tricolor accessions had high p50 values of 19.5 and 32.8 days, respectively, compared with the C. moschata and G. max accessions, which returned p50 values of 8.2 and 4.9, respectively. This means that these leafy amaranths have a long seed longevity compared with other vegetable crops. This suggests that properly dried seeds of amaranth crops can be stored for long periods of time at 5°C in aluminium foils.

Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

Chaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of weed seed containing chaff material into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavourable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, while chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine 1) the influence of chaff lines on the summer-autumn seed survival of selected weed species; and 2) the influence of chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P>0.05) in survival of seed of four weed species (rigid ryegrass, wild oat, annual sowthistle and turnip weed) when these seed were placed beneath or beside chaff lines. There was one instance where wild oat seed survival was increased (P<0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship where there was approximately a 2.0% reduction in emergence with every 1.0 t ha-1 increase in chaff material. This relationship was consistent across wheat, barley, canola and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies indicated that chaff lines may not affect the over summer-autumn survival of the contained weed seeds but the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40 t ha-1).

Black Plastic Tarps Advance Organic Reduced Tillage I: Impact on Soils, Weed Seed Survival, and Crop Residue

Intensive tillage degrades soil structure, decreases soil organic matter, and can cause soil compaction and erosion over time. Organic vegetable farmers are often dependent on tillage to incorporate crop residue, control weeds, and prepare seedbeds. Black, impermeable, polyethylene tarps applied on the soil surface and removed at planting can help suppress weeds before planting and reduce farmers’ reliance on tillage. However, little is known about how black tarps affect planting conditions and how they can be used to advance reduced tillage production systems. This study investigated the effects of tarp use and tarp duration on the soil environment, surface cover crop residue, and weed suppression to assess the efficacy of using tarps to improve reduced- and no-till practices for organic vegetable production. Experiments were conducted at three sites in the northeastern United States (Freeville, NY; Riverhead, NY; and Monmouth, ME) for 2 years. Following the termination of an oat cover crop, tarps were applied over untilled soils and left in place for four time periods: untarped (control), 3 to 5 weeks (short), 6 to 8 weeks (mid), and 10 or more weeks (long) before two removal dates. Soil moisture and temperature, cover crop residue, soil inorganic nitrogen, weed seed survival, and weed percent cover were measured after tarp removal. Soil moisture and temperature were generally higher under tarps at the time of removal compared with untarped areas at 10% to 55% and 1 to 3 °C, respectively, but the effects were inconsistent. Tarps significantly increased soil nitrate concentrations by 2-times to 21-times with longer tarp durations, resulting in higher concentrations compared with untarped controls. Tarps did not affect the amount of soil covered by cover crop residue and had no consistent effects on weed seed survival of Amaranthus powellii S. Wats. or Chenopodium album L., two common annual weed species in the Northeast. Tarping for at least 3 weeks reduced the weed percent cover by 95% to 100% at the time of removal. Increasing tarp duration beyond 3 weeks did not affect any measures except soil nitrate concentrations. These results indicate that tarps can facilitate the use of reduced-till and no-till practices for organic vegetables by creating a nutrient-rich and moist soil environment free of emerged weeds before planting without soil disturbance.