Annual Crops: Wheat

"Annual Crops" delves into the world of crops that complete their life cycle within a single growing season. This book provides an in-depth exploration of various annual plants, from essential food crops like wheat, corn, and rice to lesser-known vegetables and legumes.

With a focus on the agricultural and ecological significance of annuals, the book covers everything from planting techniques and soil requirements to harvesting and crop rotation strategies. It explores how these crops contribute to sustainable farming practices and the global food supply.

Through rich case studies, scientific insights, and practical advice, Annual Crops serves as a valuable resource for farmers, gardeners, and agricultural enthusiasts alike. Whether you're a beginner or a seasoned professional, the book equips readers with the knowledge to grow, manage, and optimize annual crops for maximum yield and environmental benefit.

Perfect for those seeking to understand the nuances of annual crop production, this guide emphasizes the importance of these plants in shaping modern agriculture and ensuring food security worldwide.

2. TEMPERATE CEREALS

2.1. Wheat

Wheat (Triticum aestivum L.) is one of the major food crops in the world. A recent report by FAO (2012) estimates the world wheat production to have risen to a record 700 million tons in the year 2011 from 553.92 million tons in 2003/2004, 607 million in 2007 and 655.7 million tons in 2010 (FAO, 2012). In Kenya, wheat is second to maize in importance with an annual production of 0.2 million tons in 2009, 0.25 million tons in 2010, 0.2 million tons in 2011 and 0.25 million tons in 2012. Production cannot meet the demand which has been growing at 5% per annum in recent years to 0.9 million tons in 2012 (FAO, 2012) which only meets 40% 0f national requirement. Wheat production in Kenya and other sub-saharan countries is challenged by drought coupled with a number of factors ranging from biotic for instance disease, weed and pest attacks to abiotic for low soil fertility etc. This has caused production to stagnate.About 32% of the wheat cultivating regions in developing countries experience drought stress during the growing season.

Wheat or bread wheat (Triticum aestivum) can be classified as winter wheat or spring wheat (depending on season) or by gluten content, such as hard wheat (high protein content) vs. soft wheat (high starch content), or by grain color (red, white or amber). Bread wheat protein content ranges from 10% in some soft wheats with high starch contents, to 15% in hard wheats. This protein can determine the suitability of a wheat to a particular use since a strong and elastic gluten present in bread wheats enables dough to trap carbon dioxide during leavening, but elastic gluten interferes with the rolling of pasta into thin sheets. The gluten protein in durum wheats used for pasta is strong but not elastic. Many wheat varieties are reddish-brown due to phenolic compounds present in the bran layer which are transformed to pigments by browning enzymes. White wheats have a lower content of phenolics and browning enzymes, and are generally less astringent in taste than red wheats. The yellowish color of durum wheat and semolina flour made from it is due to a carotenoid pigment called lutein, which can be oxidized to a colorless form by enzymes present in the grain.

Agronomy

Wheat normally needs between 110 and 130 days between planting and harvest, depending upon climate, seed type, and soil conditions (winter wheat lies dormant during a winter freeze). Optimal crop management requires that the farmer have a detailed understanding of each stage of development in the growing plants. In particular, spring fertilizers, herbicides, fungicides, growth regulators are typically applied only at specific stages of plant development.

AGRO-ECOLOGYSUITABLE FOR WHEAT FARMING

-Best climate is medium to high altitude areas with altitude range from 1200 masl to 2400 masl.

-Rainfall should be 1000-2000 mm rainfall with 500-750mm per growing season

-Temp 15-22 0C and night temps should not fall below 70C causing frost damage

-Soils should be clay light loams with good fertility, low acidity, pH 5-7

Nutrient requirements

DAP at 200kg/ha at planting, if N is deficient Calcium ammonium nitrate (CAN) can also be applied just before sowing (basal) or broadcast (top dressing) at tillerig and at boot stage, i.e., just before the panicles (heads that bear flowers) emerge. It may also applied as foliar with fungicides. Copper (Cu) is a micronutrient and therefore required in very small amounts for protein and enzyme production. Copper is involved in the following ways:-

· It promotes seed production and formation, It plays an essential role in chlorophyll formation and is essential for proper enzyme activity

If wheat is grown in deficient soils, the plant leaves becomes yellow, the leaf tips start die and become twisted. Seed / grain formation is inhibited and crop can die in severe deficiencies.

Remedy

Application: The rate of 1kg /ac is usually a general recommendations for Kenyan soils that are deficient in Cu. Its application is therefore intended to correct deficiencies and should be incorporated before planting, (along with other fertilizers), or as foliar application (on leaves). Foliar applications of Cu is most effective when applied attillering. Tillering occurs between 30 50 days after sowing. Copper sulfate (CuSO₄) is the most commonly used material for foliar

Major Diseases

Wheat stem rust has been a major problem to wheat farmers in East africa. Its caused by fungus called Puccinia tritici. The stem rust had been controlled through breeding of resistant varieties by KALRO Njoro until late 1990s when a new strain of disease called Ug 99 was introduced from Uganda in 1999 that broke down the resistance of most varieties and damaged all varieties in Kenya causing huge losses mainly in medium and high altitude areas. -Global work is working to prevent the spread of Ug99 to Asia, which is estimated to produce 26 percent of the global wheat crop. Stem rust also known as black rust is a fungal disease that causes yield reductions to wheat farmers in Kenya. The disease can move long distances by wind and develops in warm and moist environment, which is typical of all the wheat growing areas of Kenya.

Symptoms

It attacks all the above parts of the plant. The symptoms are long reddish brown of spores on the affected part of the wheat plant. The spores are known as urediospores which are similar to rusted iron rod or metal. The epidermis is ruptured and rough. As the plant approaches maturity, the spores turn dark brown to black (hence the name black rust). Stem rust produces reddish-brown, elongated pustules on the stems, leaves, glumes, awns and kernels. These contain masses of brown spores. As the plant matures later in the season, the pustules produce black overwinter spores. Infected plants produce few tillers, harvested grains are smaller and shriveled, hence low yield of low quality. If not controlled, the disease can cause up to 70% or even 100% loss in yield, in case of an epidemic. It is always evolving to new races that can infect previously resistant varieties. The latest race of stem rust, popularly known as Ug99 was reported in 1999 in Uganda. The Ug99 was confirmed in Kenya and Ethiopia since 2005, and has led to the susceptibility of commercial wheat cultivars causing serious damage.