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.

Pre-sowing treatments for improving emergence of bitter gourd seedlings under optimal and sub-optimal temperatures

Abstract: Bitter gourd (Momordica charantia L.) requires high temperature (between 25 and 28°C) for successful seedling emergence, and poor emergence is common at sub-optimal temperature. This study evaluated the effect of suboptimal temperature on seedling emergence and several physiological characteristics related to seedling growth in bitter gourd cultivar Special Six. Priming was achieved by mixing the seeds with moist No. 3 vermiculite, incubating at 25°C for 36 h, then air-drying to the original moisture level. Warm water soaking was achieved by soaking the seeds in water at 50°C for 60 min, and then air-drying to the original moisture level. Seedling emergence from vermiculite was determined at 25, 20 and 15°C. The emergence of non-treated seeds at 25°C was 50%. No seedlings emerged at 20 or 15°C. However, both priming and warm water soaking improved the emergence responses of bitter gourd seeds under 25 and 20°C. The observed decrease and delay in emergence at sub-optimal temperature were linked to the reduced activity of enzymes (i.e. isocitrate lyase, malate-synthase and malate dehydrogenase) involved in lipid and sucrose conversion. Both priming and warm water soaking improved the low temperature (20°C) seedling emergence. These improvement were attributed to the increased enzyme activities. Nevertheless, the morphological changes and softening in seed coat and seed treatment-stimulated embryo growth might also play crucial role in speeding up the seedling emergence.

Dry matter accumulation and water use relationships in wheat crops

Abstract: In order to better understand crop growth (dry matter accumulation, DM), crop evapotranspiration (Et), and their interrelationships, we studied dryland crops of wheat (Triticum aestivum L. cv. Timgalen) sown at various dates and seeding densities in each of three years at Tamworth, N.S.W. Soil water stress was minimal before anthesis in each year, but in two years substantial stress arose before maturity. DM was increased consistently by increased plant density, and decreased at anthesis and maturity by later sowing. Crop growth rates determined over 2-week intervals around anthesis ranged from 3 to 20 g m-2 d-1, representing a range in efficiency of utilization of intercepted total solar radiation of 0.48 to 2.35%, variation which was adequately explained (R2 = 0.80) by ontogeny (days from anthesis) and Et / Ep ratio (Ep = class A pan evaporation). Et at anthesis, but not at maturity, was increased slightly by higher seedmg density; crop Et was not consistently affected by sowing date. Et / Ep over 2-week periods around anthesis was related to leaf area index, and to a lesser extent to available soil water and Ep (R2 = 0.58). For the period from the first sowing date in June or July until the middle of October, the relationship of total Et to DM production was linear and close each year, but the slope varied from 6.2 g m-2 mm-1 (cold dry year) to 14.0 g m-2 mm-1 (wet year). This variation could be attributed to annual variation in the soil evaporation component of Et, and in the ratio of DM to crop transpiration (= transpiration efficiency, TE). For 2-week periods around anthesis, TE ranged from 2.9 to 5.4 g m-2 mm-1 and was inversely related to Ep (R2 = 0.56). Provided soil evaporation can be allowed for, since it ranged from 18 to 41% of crop Et from sowing to maturity, it is argued that the crop transpirationtranspiration efficiency approach is particularly useful for analysing the growth and water use of dryland wheat.

Effect of sowing date on the temperature response of leaf emergence and leaf size in barley

Abstract: Rate of leaf emergence of barley grown in the field in each of 2 years was affected by sowing date and, where direct comparisons were possible, it was found that leaves on late-sown plants emerged more quickly. Rate of leaf emergence fluctuated throughout the season, slowing almost to zero in the winter. Much of this variation in rate was removed when the number of leaves was plotted against accumulated temperature rather than time. When emergence rates for each sowing were calculated using a common base temperature they were found to be well correlated with rate of change of daylength. However, it was (bund that base temperature as well as temperature response was affected by date of sowing. The pattern of change of size of leaves was also affected by date of sowing. It appeared that in low temperatures and short days, there was no increase in leaf size from leaf position to leaf position. The responses of leaf emergence, extension and final size to date of sowing appear to adapt the plant to grow quickly when sown early but to cease growth and possibly frost-harden at low temperatures.