Effect of Intercroping Maize-Soybean on Grain Quality Traits in Kenya

An experiment was conducted in Kenya to determine the effect of intercropping maize-soybean on soybean grain quality traits. A randomized complete block design replicated three times with seven treatments was used. Data were collected and analysed for soybean protein content, oil content and dry matter while grain size was done for maize and soybean. Data were subjected to ANOVA and means separated using LSD0.05. The results showed that TGX1990-5F variety recorded high protein content (p ≤ 0.05) in sole crop compared to intercropping with 42.96% and 38.4% respectively while SB19 obtained 36.57% and 40.41% of protein between sites for the first season. A bout the second season, TGX1990-5F gave 40.84% of protein compared to 31.98% for GAZELLE in intercrop at both sites. GAZELLE showed higher oil content followed by TGX1990-5F and SB19 was the last in both seasons. TGX1990-5F showed higher dry matter followed by GAZELLE and SB19 was the last in intercrop. In addition, GAZELLE a local variety showed greater size than SB19 in both rainy seasons. Intercropping affected slightly the protein content, oil content and gain size than sole crop but it did not affect the dry matter in both seasons.Thus, TGX1990-5F can be recommended to small-scale farmers for intercropping with maize because it produced higher value of protein and small-scale farmers could use it to fight mal nutrition. GAZELLE variety can be also recommended for oil production. Maize grain size was not affected by intercropping system.


Introduction
Soybeans (Glycine max) serve as one of the most impotant crops in the world, not only as an oil seed crop and feed for livestock and aquaculture, but also as a good source of protein for the human diet and as a biofuel feestock (Masuda & Goldsmith, 2009).The world soybean production increased by 4.6% annually from 1961 to 2007 and reached average annual production of 217.6million tons in [2005][2006][2007] (Masuda & Goldsmith, 2014).Weinhold and Killick (2011) reported that, the increase of soy production both reduces poverty indicators and raises median rural incomes.Soybean cultivation is highly concentrated geographically, with only four countries-USA, Brazil, Argentine and China-accounting for almost 90% of wold output.Asia-excluding China-and Africa, the two regions where most of the food insecure countries are located, together account for only 5% of production.Among countries classified as undernourished, only India and Bolivia are significant producers of soybeans (Thoenes, 2015).In addition, Bill and Melinda (2011) reported that, for the African coutries, the leading production is South Africa (588 k MT), Zambia (112 k MT), Zimbabwe (50 k MT), Malawi (73 k MT), Mozambique (18 k MT), Angola (15 k MT) and DRC (5 k MT).The remarkable success of the soybean in temperate zones is well known, but there is also a good potential role for the crop in many cropping systems of the tropics and subtropics, where farms tend to be smaller and less mechanized (Thoenes, 2015).Among those tropics countries Kenya is included but its pourcentage soybean production is quite low and is not quoted above as soybean producer counrty.The cropping system which could help small scale famers to raise their production could be the intercropping.However, Protein content, oil content and grain size can be affected positively or negatively by growth conditions of crops (Lithourgidis et al., 2011).Intercropping, the agricultural practice of cultivating two or more crops in the same space at the same time, is an old and commonly cropping system used which targets to match efficiently crop demands to the available growth resources and labor (Lithourgidis et al., 2011).The stability under intercropping can be attributed to the partial restoration of diversity that is missed under sole crops.According to this statement of view, intercropping allows high insurance against crop failure, notably in environments known for heavy weather conditions like frost, flood, drought, and overall provides hight financial stability for farmers (Lithourgidis et al., 2011).Moreover, legumes enrich soil by fixing the atmospheric nitrogen transforming it and other mineral from an inorganic form to forms that are avaible for uptake by crops (Li et al., 2012).However, more interaction mechanisms that happen between plant species when intercropped as well as the effect of intercrop on the following crop in the fallow might have effects on grain quality.This has been shown determining the effect of intercropping on a series of quality factors, such as physical grain quality, ratio of nitrogen and sulphur concentrations, protein quality for wheat and fababean (Erik, 2005).Musa et al. (2011) reported that intercropping increased chemical composition as dry matter, ash, protein, fibber content and tannin content of cowpea in maize-cowpea intercropping.Eskandari and Ghanbari (2009), Yucel and Avci (2009) showed that, intercropping legume-cereal increased crude protein than monocrop, while Jayanta et al. (2015) found that, intercropping maize-soybean increased protein and nitrogen content in both grains, nitrogen content in stover and total nitrogen uptake with 75-100% of recommended nitrogen.Moreover, Abdel et al. (2016) revealed that intercropping soybean-sunflower spaced at 20 cm (soybean) had the highest grain oil yields per ha compared to other spacing.In addition, intercropping maize-soybean affected negatively the value of soybean protein and oil content where in pure crops soybean showed 38.47% compared to 36.76% in intercrop for protein and 19.15% compared to 17.97% for oil content respectively in sole crop compared to the intercrop (Mirela & Roman, 2013).Dragicevic et al. (2017) reported that, some chemicals content (antioxidant) were enhanced mostly by alternating strips in maize grain and by alternating rows in soybean grain, in maize-soybean intercropping system.Furthermore, intercropping maize-soybean with increasing N application can improve grain of maize and soybean physiological characters, but their effects will be decreased with increasing N fertilisation rate (Zhang et al., 2014).However, intercropping of pea-barley like a way of improving complementary N, increases the protein production and reduces weed problem in intercropping systems without herbicide use (Hauggaard et al., 2001).Laurent et al. (2014) reported that, intercropping seems to be a important agronomic solution for organic arable cropping, especialy in low-N input systems, by improving yields of environmental competition for resource use, cereal grain protein concentration due to non proportional competition for soil mineral N and other plant growth factors, weed control, compared to sole crops.Nevertheless, analysis of grain quality in cereals-legumes cropping system showed that, crude protein concentration of intercropped cereals increased compared to sole crops in all experimental sites.Pea increased the concetration of crude protein in intercrops yield compared with sole cereals in the Dotnura site (Kadziuliene et al., 2009).Moreover, Staniak et al. (2014) found that, intercropping of cereals-legumes enhances protein content in the grain cereals, increasing also the yield of crude protein in the biomass of the component crops.Šarūnaitė et al. (2010) said that,the increases of crude protein was higher in wheat grain yield when wheat had been grown in intercrop with bean.In addition, intercropping had no significant effect on grain oil content of castor.It was concluded that, castor, could be intercropped efficientely with beans without affecting food crop production and the resultant grain oil content of castor.Hence the need in this study to assess the effect of intercropping maize-soybean on protein, oil content and grain size at Embu and Mwea sites in Kenya.

Materials and Methods
The experiments were carried out in two sites during two rain seasons of (2016 and 2017).The first site was KALRO-Embu, located in Embu County in the Eastern part of Kenya and lying between latitudes 0°08′35″ S and a longitude 37°27′02″ E. KALRO-Mwea is in Kirinyaga county, situated in the Central Region of Kenya at a latitude of 00°37′ S and a longitude of 37°20′ E (Kirinyaga county, 2014 and Embu county, 2014).Land preparation was done by ploughing using ox-drawn equipment.The varieties of soybean used were: SB19, GAZELLE, TGX1990-5F and one variety of maize (Duma 43) for intercropping with soybean.The experiment was laid out in a randomized complete block design (RCBD) replicated three times with seven treatments including: T 1 : SB19 (Hybrid), T 2 : GAZELLE (Local), T 3 : TGX1990-5F (Hybrid), T 4 : SB19+MAIZE, T 5 : GAZELLE+MAIZE, T 6 : TGX1990-5F+MAIZE, T 7 : MAIZE (DUMA 43).The spacing used and densities were: Monocrop soybean: 166,666.66plants ha -1 (40 cm × 15 cm), Soybean intercropped with maize: 83,333.33plants ha -1 (80 cm × 15 cm), Monocrop maize: 50,000 plants ha -1 (80 cm × 25 cm), Maize intercropped with soybean: 50,000 plants ha -1 (80 cm × 25 cm).The total area of the experiment was 420 m 2 .In total, the experiment had 2700 plants of soybean in which 900 plants were in intercrop with maize and 1800 plants were in sole crops.The total density in whole experiment for maize was 720 plants in sole crops as in intercrop.The arrangement of intercropping was 1:1 with, one row of maize intercepted by one row of soybean.The experiments received a basal application of 10.5 kg of DAP per site at the rate of 250 kg ha -1 , meaning that each plot received 300 g of

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Soybean g SB19 reco value of 2. last was G same in th sites and s with 1.7% showed th for SB19 bigger than soybean w affected ne Mwea site other varie was 96% a Fi Grain size (p ≤ 0.05).against (7 seasons.In    t rains 2016-20 016, but diffe her in the long % to 43% at M hort rains, it ra ring the long bu while it wa wed by GAZE duced more pr 9% at Embu.F 9.36% in sole the higher valu showed the hig in content of s (p ≤ 0.05), SB19 in inter followed by S content becaus Table 1).How nd GAZELLE B19 with 16.46 0-5F with 12 ues of oil conte 2.78%.GAZE west oil conte 990-5F was in ontent for both seasons (p ≤ 0 14% to 16% fo op.The signif y matter of 18 y showed the ter of 15%.Fo n 16.77% for S of 18.82% follo uring the long ntercropping an ge (Table 1).Note.LSD: Least significant difference; CV: Coefficient of variation.

Effects of Intercropping Maize-Soybean on Grain Size
The higher values of soybean grain size had 6.5 mm in both sites, where GAZELLE recorded 79.33% compared to SB19 with 0.67%.Intercropping affected negatively soybean grain size according to the results found in both rainy seasons.This could be due to not only the competition of maize against soybean on nutrient, light and air but also the results of shading of maize on soybean.From this results, William (2012) reported that variety with early maturity are the most to give poor grain quality especially for those variety which their maturity are not unifom.Wet conditions, shading, pressures of some diseases, poor conditions between pysisological maturity and harvest can enhance decreasing of grain quality.SB19 variety known for early maturity produced poor grain quality because of criticals conditions which revealed during the two rainy seasons.Ranking soybean size, GAZELLE had better grain size followed by TGX1990-5F and the last is SB19 (Figure 5).From results, Foundation (2011) reported that GAZELLE is a variety largely cultivated in Kenya and was released in 2009 by KARI Njoro and is high yielding, large grain size, and attractive color.Whan et al. (2014), reported that, grain size is an important trait of both basic plant reseach, since grain formation and development is a fundamental aspect of reproduction, and breeding, as a component of yield and vigour.Thus, each control methods determining grain size tend to either know if grain size did increase or decrease depending of growing conditions.The high value of soybean good grain size ranged from 5.6 mm to 8 mm.These results have been confirmed by Shahin and Symons (2005) who reported that, depending on the varieties of soybean, grain size can range between 5.56 mm to 7.54 mm.

Effects of Intercropping Maize-Soybean on Protein, Oil Content and Dry Matter
According to the results found, TGX1990-5F showed significant difference producing high value of protein ranged between (34.94% to 43.02%) at both sites and during two rains seasons.The second variety to produce high value of protein is the local variety which is GAZELLE and the last is SB19.Intercropping affected slightly the protein content considering the higher value of protein content for each variety produced in sole crop than in intercropping.GAZELLE variety produced highest value of oil content (21.08%) compared to SB19 (16.46%) at Embu in long rains of 2016.The variety which had the lowest value of oil content was SB19.GAZELLE produced high value of oil content both sites and both rain seasons.Intercropping affected slithly the value fo oil content than sole crop.This could be attributed on the shading of the maize on soybean which could not allow good panetration of light, air, and the competition of nutrient, hence, low protein and oil production.Depending on the results obtained Lithourgidis et al. (2011) found that grain quality traits, protein content and oil content can be affected positively or negatively by growth conditions of crops.In contrary, Erik (2005) reported that, intercropping can have series of quality factors, such as physical grain quality, ratio of nitrogen and sulphur concentrations, protein quality for wheat and fababean.The spacing of soybean between plant was 40 cm while it was15cm within plant which allowed good oil production in maize-soybean intercropping.That was not the case for Abdel et al. ( 2016) who reveled that intercropping soybean-sunflower spaced at 20 cm (soybean) had the highest grain oil yields per ha compared to others spacing.Ayu et al. (2004) recorded maximum protein yield of sorghum under soybean plus sorghum system than sole sorghum.In many cereal-legume intercropping systems there is emanation of favourable exudates from the component legume to the associated cereal and this is suspected to have effects on the quality of the cereal in terms of protein yield.Moreover, Staniak et al. (2014) found that, intercropping of cereals-legumes enhances protein content in the grain cereals, increasing also the yield of crude protein in the biomass of the component crops.Šarūnaitė et al. (2010) said that,the increases of crude protein was higher in wheat grain yield when wheat had been grown in intercrop with bean.However, depending on dry matter, TGX1990-5F gave significant diference of dry matter (18.82% compared to 15.11%) for SB19 at Mwea for long rains of 2016.Embu site did not give significant difference during long rain of 2016 and short rains of 2016-2017.Futhermore, Musa et al. (2011) reported that intercropping increased chemical composition as dry matter, ash, protein, fiber content and tannin content of cowpea in maize-cowpea intercropping.In addition, Rusdy (2014) showed that intercropping of Panicum maximum and Centrosema pubescens gave dry matter which was significantly different (p < 0.05) than their monocrops.

Conclusion
Intercropping maize-soybean showed that TGX1990-5F variety presented high value of protein content in sole crops and in intercrops followed by GAZELLE compared to SB19.For the oil content, GAZELLE came first showing high value of oil content while TGX1990-5F was second.TGX1990-5F can be recommended to smallscale farmers for intercropping with maize because it can produce high protein content and fight against mal nitrution, and increase maize yields.GAZELLE had higher grain size compared to other varieties. Figu

F
Fig

Table 1 .
Soybean protein content, oil content and dry matter atEmbu and Mwea 2016-2017