GUAR:forgotten cropgrowing in most marginal conditionsmany modern applications
Guar - Introduction • Guar is a drought tolerant annual legume that grows in hot, semiarid regions with sandy soils • The major world suppliers are India, Pakistan, the United States and smaller acreages in Australia and Africa • The world demand for Guar increased which lead to introduction of Guar in other countries
Guar - Crop properties • Guar is an upright course-growing summer annual legume (18-40 inches) (45-100 cm) • The deep roots reach deep moisture • Leaves, stem and pods are smooth • The Guar bean has a large endosperm • The endosperm contains large amounts of gum which is the marketable product of the plant
Guar – Some examples of use The gum of Guar forms hydrates rapidly in water into a viscous gel and is therefore used in various products • In Asia: • Beans for vegetable consumption • Crop for cattle feed • As green manure • In the United States: • No calorie binding agent • fi stiffener in soft ice cream • In pharmaceutical industry • In cloth and paper manufacture • Oil well drilling muds
Guar – climate and soil • Drought resistant • High toleration of temperature (77 to 95˚F) (25 to 35˚C) • Grows well under a wide range of soil conditions, but preferably fertile, medium textured and sandy loam soils • Salinity and alkalinity tolerant • Soil improving crop • Fits in crop rotation program (with grain sorghum, small grains or vegetables)
Cultivation - Seed preparation • Select seeds with same size and colour • Selected seed must be free from other crop and weed seed • Select seed from the most recent varieties (New varieties are more resistant to diseases) • Inoculate the seed before planting with a special guar inoculant (or a cowpea inoculant) • Plant the seeds in moist soil within 2 hours after inoculation • The seed bed should be free of weed
Cultivation – Seeding date • Plant Guar when soil temperature is over 70˚F (21°C) • Optimum temperature for germination is 86˚F (30°C) • Essential conditions: • Warm seedbed • Adequate soil moisture • Warm growing weather
Cultivation – Seeding and fertility • With row crop planter, Guar can be planted in rows from 36 to 40 inches. (90-100 cm) • Planting depth of 1 to 1.5 inches deep (2.5-4 cm) • Guar requires a high level of phosphorous (22 to 34 kg of P2O5/ha) and a medium level of potash (45 to 56 lb of K2O/ha) • Apply fertilizer before planting and below the seed • Optimum pH value is between pH 7 an pH 8
Guar varieties in USA • Brooks; (1964); first improved variety. High yielding and resistant to major diseases. • Hall; later maturing compared to Brooks. Resistant to bacterial blight and Alternaria leaf spot. Best adapted to heavier soil types and higher elevation. • Mills; Early maturing and also resistant to bacterial blight and Alternaria leaf spot. Lower yields than Hall and Brooks. • Kinman; (1975) a week earlier in maturity than Hall. Highly resistant to bacterial blight and Alternaria leaf spot. • Esser; (1975) medium to late in maturity. Better disease tolerance than Brooks. • Lewis: (1986) Medium to late maturing. Seed yields are approximately 25% higher than Kinman.
Control Measures Weed control Because of the slow growing rate of young Guar plant, weed control is important • Mechanical control: • Do not seed Guar in fields with Johnson grass and other perennial weeds • Early land preparation minimizes weed problems • Chemical control: • Treflan (selective herbicide) can be used to control annual grasses and annual broadleaf weeds Diseases control • Select disease-resistant varieties and high quality certified seed to prevent Guar from Alternaria leaf spot (fungal disease) and Bacterial blight (seed-borne disease causing plant losses) Control of insects and other predators • Guar Midge is the primary insect pest in the Southwest of the USA. Rainfall or sprinkler irrigation may reduce the midge population
Harvesting • Seed pods are brown and dry at maturity • To speed up drying and to kill weeds, Gramoxone (paraquat) can be used • Guar beans can be harvested with a normal grain combine • To clean out foreign materials use a high fan speed • Reels should be set deep enough in the Guar to control stalks (15 to 30 cm ahead of the cutterbar) • For hay: cut crop when first pods turn brown • For green manure: Guar should be turned under when lower pods turn brown • For seeds: after harvesting Guar can be used as mulch when it is plowed under
After harvesting • Income and production costs vary every year and are also depending on soil types • Yields vary from 55 to 360 kg per hectare • Production costs are between 8 and 16 USD/hectare. (depends on fertilizer usage and other production practices
Situation in Pakistan • Guar is poor man’s crop • Only a few guar gum processing plants – that are struggling to survive • Quality issues • Guar processing needs revival and international marketing effort!
Sources of Pictures • Sheet 1 – www.niemagazine.com • Sheet 2 - www.plthomas.com/guar.html • Sheet 3 - juniper.tamu.edu/Agronomy/guar_pods.htm • Sheet 4 - http://www.shreevinayakcorp.com/guar-gum.html • Sheet 8 - http://www.guar-tex.com/images/seed.jpg • Sheet 12 - http://milksci.unizar.es/bioquimica/temas/azucares/ auxiazucar/cyamopsis.jpg