Journal of Agronomy

Year: 2005 | Volume: 4 | Issue: 4 | Page No.: 333-339
DOI: 10.3923/ja.2005.333.339

Agronomic Factors on Selected Hulless Barley Genotypes

Hamid Reza Balouchi, Zeinalabedin Tahmasbi Sarvestani and Seyed Ali Mohammad Modarres Sanavy

Abstract: Yield and yield components evaluation of different hulless barley (Hordeum vulgare L.) genotypes with objective determination of the best plant density and nitrogen fertilizer rate is necessary for obtaining maximum quality and quantity yield. In the first year, for these propose twenty genotypes were evaluated in aspect of quality and quantity yield. In second experiment, ten best genotypes selected from the first experiment were evaluated for agronomic factors such as plant density and N fertilizer rate application. Both experiments were conducted in Research Farm of Tarbiat Modarres University, College of Agriculture, Tehran, Iran during 2001-2003 growing season. The experimental designs of first and second experiments were Randomized Complete Block and Split-Split-Plot laid out in Randomized Complete Block designs, respectively, with three replications and a total of ten genotypes (as main plot), 2 levels of nitrogen fertilizer (90 and 120 kg nitrogen ha^-1 as subplot) and 3 plant densities (300, 400 and 500 plants m^-2 as sub sub-plot). The results showed that a significant difference between genotypes and plant density interaction in grain yield and harvest index. The highest grain yield, spike number m^-2 and grain number spike^-1 were produced by ALLSO`S`/C103902-2 genotype under 500 plant m^-2. FICC2595 Genotype showed the highest thousand-kernel weight (46 g) and FICC1570 genotype produced the highest spike number m^-2 (958 spike m^-2). The mean comparison of protein yield in different plant density m^-2 showed that 500 plants m^-2 treatment produced the highest protein yield (58.48 g m^-2).

Keywords: yield components, yield, nitrogen fertilizer, plant density, Hordeum vulgare L., and Hulless barley

INTRODUCTION

Barley (Hordeum vulgare L.) has the widest geographical range of distribution of all cereals. In temperate, humid climate, barley can be sown in an autumn and harvested after about 300 days. It also grows under arid climates. The varieties adapted to the respective conditions are quite different from each other. All of these many types of barley developed characteristic traits, which always refer to the environmental conditions. One character of special interest, which has developed in different areas, is the feature of free threshing grains, i.e., the grains are not covered with the glumes after threshing (hulless barley).

Hulless barley research and development is now receiving more emphasis with potential for feed, food and industrial uses. Variety selection is and will become more important as the various industries demand specific characteristics. Feeding value depends on its protein and energy contents. In agriculture, besides the grain quality, the adaptation of the varieties to the respective site of cultivation is the greatest importance.

Hulless barley is important source of water-soluble plant fiber needed in human diets to lower serum cholesterol. Reported benefits of water-soluble plant fiber from hulless barley^[1] in lowering human serum cholesterol have increased the interest in producing hulless barley for human consumption. Thus, production practices such as plant density and N fertilization may be important.

The hull comprises 10-13% of barley dry matter^[2], therefore its absence in hulless forms results in the greater content of nutrients, mainly protein and fat. The presence of hull, which is made up of chiefly cellulose and lignin, decreases the digestibility of all nutrients.

Hulless barley is very well suited to Iran region fitting well with the cropping systems and potentially providing grain for the poultry industries in addition to current uses. Hulled barleys have not generally been fed due to the high fiber content and hulless barley has not been utilized due to the low yield varieties for the Iran region.

Hulless barley has the potential to produce yields similar to wheat with a combination of positive nutritional qualities from hulled barley and wheat^[3].

Compared with hulled barley cultivars, hulless cultivars have reduced fiber content and increased starch content due to the absence of the hull^[4]. The crudeprotein of hulless barley typically exceeds that of comparable hulled types and should be 1-2% greater. Hulless barley has a major advantage over conventional barley in transportation, processing and storage. Removing the hull fraction increases the bulk density (weight-per-unit volume) compared to conventional barley by about 25 %.

Grain yield in barley depends mainly on spikes m^-2 and kernels spike^-1[5-8]. Yield components are formed during successive stages in the ontogeny of plants and earlier formed components influence those that develop later^[5]. Previous studies have shown that yield components such as grain yield; spike number m^-2, grain number spike^-1 and thousand kernel weight interact with yield and thereby in the affect grain yield^[5,7,8]. Thus plant population density influence on spikes m^-2 and thereby in the affect grain yield.

Good understanding from plant nitrogen future is major objective in developing utilization of nitrogen and mineral fertilizer and reducing contamination of subterranean water^[9]. Morgan and Smith^[10] investigated the effect of 0, 45, 90, 135 and 180 kg ha^-1 nitrogen rates on spring wheat. They showed that the most grain yield and grain nitrogen rate were obtained from 135 and 180 kg ha^-1 nitrogen treatments, respectively. Previous studies reported positive effect of optimum nitrogen fertilizer application on grain yield^[11-14]. High nitrogen application increased forage protein yield due to more nitrogen absorption and increasing vegetative growth (15).

Numerous studies have been conducted to examine the effect of plant density and N fertilizer on yield of small grains. However, few experiments have examined the influence of agronomic factors in hulless barley. The objective of this study was to rank 20 barley genotypes on the basis of their protein and yield. Then the selected genotypes were evaluated for the best nitrogen fertilizer rates and population densities for acquiring the maximum quality and quantity yield.

MATERIALS AND METHODS

This study included two field experiments planted at the Research Farm of Tarbiat Modarres University, College of Agriculture, (35°43´ N Latitude, 51°8´ E Longitude and 1215 m Altitude), Iran, for two growing seasons in 2001-2002 and 2002-2003. Yearly average rainfall is 247.4 mm and yearly averages of the maximum and minimum temperatures were 37 and 0°C. The soil characters are shown in Table 1. Two experiments were conducted separately due to have different materials and methods.

Experiment 1: The experimental field was planted to wheat in 2000 but was a fallow in 2001. Basal fertilizers were applied to the soil including 60 kg ha^-1 (P₂O₅) ammonium phosphate and 120 kg ha^-1 urea. N fertilizer was applied two times (½ basal and ½ at active tillering stage) as top dressing. Standard cultural practices were followed. The experimental design was Randomized Complete Block with three replications. Twenty hulless barley genotypes were used for this study. Each experimental plot consisted of five 1.5 m rows with a row spacing of 20 cm. Plant density was consist of all genotypes and was 350 plants m^-2. Two middle rows in each plot were harvested for yield determination. Grain yield, thousand kernel weight and spike number m^-2, grain number spike^-1, harvest index and protein percent were recorded for each plot. Superior genotypes were selected for higher grain and protein yield. Then selected genotypes were used in second experiment.

Experiment 2: The experimental field was planted to wheat in 2001 but was a fallow in 2002. Before preparing field, soil samples were taken from 0-30 cm deep for soil physical and chemical determining. Fertilizer was applied in basis of soil analysis (Table 1). A main fertilizer including 300 kg ha^-1 ammonium phosphate (46% P₂O₅ and 18% N) was applied to the soil before planting.A split split-plot was designed with 10 genotypes (Table 2) as main plots, N treatments (90 and 120 N kg ha^-1) as sub-plots within the main plots and plant density (300, 400 and 500 plants m^-2) as sub sub-plots. There were 3 replications. Each sub sub-plot was made up of four rows of 2 m length. The rows were 20 cm apart. The adjacent sub sub-plots were separated by two blank rows. The distance between main plots was 1.5 m. Urea fertilizer (46%) were applied two times (½ basal at planting date and ½ at active tillering stage) according to N treatments. Genotypes seeds was sown on 15 November 2003. Seeds were surface sterilized with 0.02% (w/v) Mankozeb fungicide (IMP and Exp Corporation). Experimental plots were kept free of weeds and pests. At maturity, two rows of each sub sub-plots were harvested and the following data were recorded: grain yield; spike number m^-2, grain number spike^-1, thousand kernel weight, harvest index, protein percent and yield.

Statistical analysis: Results were statistically analyzed for variance using the SAS system^[16]. When analysis of variance showed significant treatment effects, Duncan’s multiple range tests was applied to compare the means at p<0.05^[17].

RESULTS AND DISCUSSION

Experiment 1
Grain yield: Present results indicated that genotypes had (p<0.01) significant difference for grain yield, thousand kernel weight, spike number m^-2, grain number spike^-1, harvest index and protein percent (Table 3). Mean comparisons showed the maximum grain yield for FICC1571 genotype with 3963 kg ha^-1 and minimum grain yield for FICC0406 genotype with 1714 kg ha^-1 (Table 4). It is seems that high yield of FICC1571 genotype is due to its high harvest index and spike number m^-2 in comparison with other genotypes (Table 4). Low grain yield in FICC0406 genotype was due to low spike number m^-2 and grain number spike^-1 in this genotype (Table 4). Many researchers^[18-22] also that believe increasing yield are due to enhance spike number m^-2.

Thousand kernel weight: FICC2712 and FICC2595 genotypes had more thousand kernel weight (47 and 46 g, respectively) than other genotypes. The lowest thousand kernel weight was obtained from FICC0409 and FICC0598 genotypes (24 g) (Table 4). More thousand kernel weight in FICC2712 and FICC2595 is due to have awn and low grain number in spike in these genotypes than others. Plant current photosynthesis is most important source for grain barley storage in suitable condition. Awn increase plant photosynthesis potential and as a result seed length and width increase and thereby in the end affect thousand kernel weight. Low thousand kernel weight in FICC0409 and FICC0598 genotypes is due to high grain number in spike of these genotypes.

Spike m^-2: ALLISSO”S”/C103909-2 genotype had the most spike m^-2 (389). This trait was the lowest in FICC0406 and FICC1329 (196 and 202, respectively) (Table 4). Higher spike number in ALLISSO”S”/C103909-2 is related to high genetic potential. There is positive correlation between spike number and grain yield. As was shown here the ALLISSO”S”/C103909-2 genotype had high grain yield. Some researchers have reported that spike number m^-2 have direct effect on grain yield, although high spike m^-2 cause to decrease grain number spike^-1[23]. As was shown (Table 4) FICC1329 genotype had the highest and lowest grain number spike^-1 and spike number m^-2, respectively.

Grain number in spike: Analysis of variance on grain number/spike was shown that grain number spike^-1 had significant difference among hulless barley genotypes (Table 3). Mean comparisons showed that the maximum grain number spike^-1 was for FICC0963 and FICC1329 (54 grain) and the minimum was observed in FICC2712 and FICC2595 genotypes (21 grain) (Table 4). Higher grain number spike^-1 in FICC0963 and FICC1329 genotypes in comparison with other genotypes are due to higher genetic potential, lower thousand grain weight and spike number m^-2 (Table 4).

Lower grain number spike^-1 in FICC2712 genotype is due to lower spike number m^-2 and thousand grain weight in comparison with other genotypes. Increasing spike number and plant population enhance competition between plants and as a result decrease grain number and increase thousand grain weight due to compensation effects.

Grain protein percent: FICC1461 and FICC0406 had the most grain protein percent (11.61 and 11.31%, respectively). The lowest grain protein percent was belong to FICC 1570 genotype (Table 4). Protein percent was high in FICC1461 and FICC0406 genotypes due to low grain number spike^-1 and spike number m^-2. There are negative correlation between protein percent with grain yield, harvest index, grain number spike^-1 and spike number m^-2. Thus FICC0406 genotype had the maximum protein percent and minimum grain yield and harvest index.

On the whole, FICC1571, FICC1725, FICC 0409, ALLISSO”S”/C103909-2 and FICC 1301 genotypes produced 3963, 3700, 3650, 3510 and 3408 kg ha^-1 yield, respectively and these genotypes had more yield than others.

FICC 1461 and FICC 0406 had the most protein percent (11.61 and 11.31, respectively). FICC 0963 had the most spike grain number and relatively high protein percent. FICC1570 had the most harvest index. The most thousand kernel weight was belong to FICC2595 and FICC2712. Therefore FICC1725 genotype with 3700 kg ha^-1 grain yield and 10.40% protein and also ALLISSO”S”/C103909-2 genotype with 3510 kg ha^-1 grain yield and 10.14% protein were determined as the best genotypes in this environment.

Experiment 2
Grain yield: There was significant interaction (p<0.01) between genotypes and plant densities for grain yield (Table 5). ALLISSO”S”/C103909-2 genotype had the most grain yield (5874 kg ha^-1) at 500 plant m^-2 (Table 6). Higher grain yield in ALLISSO”S”/C103909-2 is related to its high spike number m^-2, grain number spike^-1, thousand grain weight and 6 row-spike in comparison with other genotypes (Table 8). FICC2712 genotype with low grain yield had low spike number m^-2 and two-row spike.

Yield in other genotypes enhance with increasing population density up to somewhat and then decrease due to sensitiveness of genotypes to high population and inter competition appearance. Mazurek et al.^[24], Grabinski^[20], Anderson^[25], Piegh et al.^[21] and Stankowski^[22] which showed spike density enhancement increased grain yield. Yield decrease in high plant population decrease grain yield due to stem lodging. Grain yield had the highest correlation with spike number m^-2 (r = 0.564) and harvest index (r = 0.743).

Thousand kernel weight: The most thousand kernel weight was observed in FICC2595 (45 g) genotype (Table 8). More thousand kernel weight in FICC2595 genotype is due to its awn, more spike length (data not shown) and low grain number in spike. Plant current photosynthesis is the most important source for seed barley storage in suitable condition. Awn and spike length increase plant photosynthesis potential and as a result seed length and width increase and thereby in the affect thousand kernel weight. There was non significant effect between different plant population, nitrogen fertilizer rates and their interaction effects on thousand grain weight. These results according to Kabirian et al.^[19] Garcadel et al.^[7].

Spike number m^-2: FICC1570 genotype had the most spike number m^-2 (625) (Table 8). Higher spike number in FICC1570 genotype is related to high genetic potential. Plant density increased spike number m^-2. The most spike number m^-2 was observed at 500 plant m^-2 plant density (Table 7). There is positive correlation between spike number and grain yield, Although high spike m^-2 decreased grain number spike^-1[23]. This result is comparable to the previous report of Kabirian et al.^[19] which showed high plant densities decreased spike number m^-2 due to competition. Some researchers reported that high plant densities did not change spike number m^-2.

Grain number spike^-1: The result showed that genotypes were difference for grain number spike^-1 (p<0.01) (Table 5). Nitrogen treatments changed grain number spike^-1 in genotypes (p<0.05) (Table 5). FICC1329 and FICC0963 genotypes produced maximum grain number spike^-1 (64 and 58 respectively) (Table 8). One hundred and twenty kg nitrogen ha^-1 produced the most grain number spike^-1 (50) (Table 10). The result is similar to previous report by Kabirian et al.^[19]. High grain number spike^-1 of FICC1329 and FICC0963 genotypes is due to high genetic potential and thousand-grain weight in these genotypes.

Genetic factors control fertile floret number spike^-1, but environmental condition also has effect on floret from pollination to grain maturity^[26]. Thus, nitrogen fertilizer has positive effect on grain number spike^-1[27].

Harvest index: Genotype and plant population interaction effect on harvest index was significant at p<0.01 (Table 5). Highest harvest index was 40.32% for ALLISSO”S”/C103909-2 genotype at 500 plants m^-2 and 39.15% for FICC1570 genotype at 300 plants m^-2 (Table 7). High harvest index in FICC1570 genotype was related to its dwarf trait. High spike number and grain yield of ALLISSO”S”/C103909-2 genotype increased harvest index. Significant and positive correlation existed for harvest index with grain (r = 0.74), thousand grain weight (r = 0.37) and spike density (r = 0.16).

Grain protein percent and protein yield: Protein percent was not affected by any of treatments, but genotypes had different protein yield in different plant densities (Table 5). The most protein yield (58.48 g m^-2) was obtained at 500 plants m^-2 (Table 9). Higher protein yield can be attributed to higher grain yield. Protein yield had positive correlation (p<0.01) with grain yield (r = 0.906), thousand-grain weight (r = 0.206) and spike density (r = 0.639). Although grain protein percent had not significant difference among genotypes but protein percent had negative and significant correlation (p<0.01) with grain yield (r = –0.523) and harvest index (r = –0.652).

CONCLUSIONS

Generally, high genetic diversity was observed among genotypes for grain yield and yield components. Nitrogen rate and suitable plant density are two important factors in high production. Therefore, the following cases were proposed as conclusion:

Therefore ALLISSO”S”/C103909-2 was the best genotype in respective of grain yield, harvest index and protein yield.

ACKNOWLEDGMENTS

The authors thank to Iran Seed and Plant Improvement Institute for providing the seeds of hulless barley and like to thank Mr. A. Salehi for his excellent technical assistance.

REFERENCES