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.

Climate-driven simulation of global crop sowing dates

Abstract: Aim To simulate the sowing dates of 11 major annual crops at the global scale at high spatial resolution, based on climatic conditions and crop-specific temperature requirements. Location Global. Methods Sowing dates under rainfed conditions are simulated deterministically based on a set of rules depending on crop-and climate-specific characteristics. We assume that farmers base their timing of sowing on experiences with past precipitation and temperature conditions, with the intra-annual variability being especially important. The start of the growing period is assumed to be dependent either on the onset of the wet season or on the exceeding of a crop-specific temperature threshold for emergence. To validate our methodology, a global data set of observed monthly growing periods (MIRCA2000) is used. Results We show simulated sowing dates for 11 major field crops world-wide and give rules for determining their sowing dates in a specific climatic region. For all simulated crops, except for rapeseed and cassava, in at least 50% of the grid cells and on at least 60% of the cultivated area, the difference between simulated and observed sowing dates is less than 1 month. Deviations of more than 5 months occur in regions characterized by multiple-cropping systems, in tropical regions which, despite seasonality, have favourable conditions throughout the year, and in countries with large climatic gradients. Main conclusions Sowing dates under rainfed conditions for various annual crops can be satisfactorily estimated from climatic conditions for large parts of the earth. Our methodology is globally applicable, and therefore suitable for simulating sowing dates as input for crop growth models applied at the global scale and taking climate change into account.

Seed Ageing and Smoke: Partner Cuesin the Amelioration of Seed Dormancyin Selected Australian Native Species

Abstract: Seed germination of many Australian native plant species has consistently proven to be fractious. With the discovery of smoke-mediated germination, it is now possible to better understand the heterogeneity in germination patterns for a wide range of species both in situ and ex situ. In the present study, over 180 species were examined as to viability and smoke responsiveness of freshly collected seed. Soil storage and a number of commonly used seed pre-treatments were employed in combination with smoke to examine both longevity in artificially constructed seed banks, and the role of seed ageing in improved germination. Methods of smoke application for commercial use were also investigated. Viability decline over 1 year varied between 10% and 80%. Reductions of as little as 15% were found to compromise the ability of a number of species to successfully recruit in consecutive seasons. When fresh seed was used,almost 70% of species tested responded positively to smoke whether applied prior to or after sowing. Variation in success between the two methods confirmed earlier conclusions that substances contained in plant-derived smoke may be inhibitory at high concentrations for particularly sensitive species. Only 10% of species under investigation recorded optimum germination with seed ageing alone but when smoke was applied as a treatment after soil storage, 60% of species responded positively. Implications for horticulture, rehabilitation, seed bank research and habitat management are discussed.

Effect of increasing temperature on yield of some winter crops in northwest India

Abstract: The effect of increase in temperature on grain yield of some winter crops (wheat, mustard, barley and chickpea) in northwest India was evaluated on the basis of historic records and through a dynamic crop growth model, WTGROWS. The optimal date of sowing was also evaluated in view of the increase in seasonal temperature. The yield of these crops, especially wheat, already showing signs of stagnation in most places of northwest India, is most likely to be affected by temperature changes. The solar radiation-temperature interactions study in wheat reveals some interesting trends and is seen to vary from one location to another. Keeping in view the trends in global climate change, a shift in sowing time, as an adaptation strategy is recommended. The simple and empirical relations between yield and seasonal temperature change can be well used for a crude estimate of yield dependence of temperature rise of these winter crops.

Stabilizing Rainfed Wheat Yields with Supplemental Irrigation and Nitrogen in a Mediterranean Climate

Abstract: The West Asia-North Africa (WANA) region, with a Mediterranean-type climate, has an increasing deficit in cereal production, especially bread wheat (Triticum aestivum L.). Rainfed cropping coincides with the relatively cool, rainy winter season, usually from October to May. Cereal yields are low and variable in response to inadequate and erratic seasonal rainfall and associated management factors, such as lack of N and late sowing. In an area where water is limited, small amounts of supplemental irrigation (SI) water can make up for the deficits in seasonal rain and potentially produce satisfactory yields. This field study (1992-1993 to 1995-1996) on a deep clay soil (a Calcixerollic Xerochrept) in northern Syria was conducted for four growing seasons to assess the effects of SI (rainfed, 1/3, 2/3, and full irrigation) combined with N rate (0, 50, 100, and 150 kg ha -1 ) and sowing date (early, normal, and late) on one traditional (Mexipak 65) and three improved bread wheat cultivars (Cham 4, Cham 6, Gomam). Yields of rainfed wheat varied with seasonal rainfall and its distribution, with all main factors having significant effects. A delay in the sowing date from November to January consistently reduced yields and the response to both SI and N. With irrigation, crop responses were generally significant up to 100 kg N ha -1 , while optimum response for rainfed conditions was with 50 kg N ha -1 . An addition of only limited irrigation (1/3 full irrigation) significantly increased yields, but near maximum yields were obtained by 2/3 of full irrigation. Responses to N and SI were greatest for the higher-yielding cultivars. Use efficiency for both water and N was greatly increased by SI. Thug with minimum irrigation during the winter growing season combined with appropriate management, inputs, and varieties, wheat output could be substantially and consistently increased In the semiarid Mediterranean zone. Production functions developed from this dataset can help predict the effects of changing any of these parameters in other locations in the region.