yield and quality parameters in · pdf file03.09.2010 · 5th international congress...

5th International Congress FLOUR‐BREAD ʹ09 7th Croatian Congress of Cereal Technologists

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YIELD AND QUALITY PARAMETERS IN CONVENTIONALLY AND ORGANICALLY GROWN WHEAT

UDC 633.11 : 539.501 631.52

V. Samobor1, Ž. Vukobratović1, D. Nađ2, I. Turk2, M. Jošt3

1Agricultural College at Križevci, Croatia; e‐mail: [email protected] 2Belje d.d. Darda, PC Mlin, Beli Manastir, Croatia 3JOST seed‐research, Križevci, Croatia

ABSTRACT

Identical wheat micro trials were conducted in 2007/08 season at two separate locations near Križevci with conventional (with mineral fertilizers and pesticides) and organic (no mineral fertilizer and pesticides) approach. Surprisingly, organically grown wheat had in average 1.1 t/ha (16%) higher grain yield but bread making quality parameters were lower. The paper discusses the growing conditions and concludes that due to the green manure (Lupinus albus) organically grown wheat had enough accessible nitrogen during a heavy spring drought (enhanced tillering), while in the period of grain formation nitrogen was insufficient, resulting in lower bread making quality parameters.

In the conventional agrotechnic, due to a heavy spring drought, the applied N was accessible only after the rain (in heading period) – resulting in lower plant density but with positive effects on bread making quality parameters.

Although the experiments were conducted in only one year, the conclusion is clear: organically grown wheat, if all required conditions are fulfilled, could give equal and even greater grain yield than wheat in conventional agrotechnics. The belief of some agronomy experts that organically grown crops are less yielding is based on wrong supposition.

Key words: organic wheat, grain yield, quality parameters.

INTRODUCTION

In the second half of 20th century, as results of the Green Revolution, the global trends were industrial agriculture, based on heavy application of synthetic fertilizers and pesticides, narrow crop rotation or even monoculture, with an emphasis on a few export crops [1]. Although the average crop yields rose up tremendously, this enhanced crop production proved to be unsustainable as it degrades soil, water and environment, caused dramatic loss of biodiversity and associated traditional knowledge.

In the face of such global trends, the concepts of food sovereignty and ecologically based production systems have gained much attention in the last two decades. Demand, as well as selling prices for organic, or so called ʹhealthy foodʹ, has increased recently.


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The advocates of globalized industrial (conventional) agriculture claim that organic agriculture yield less and are not able to feed the world. Although the conventional wisdom is that small organic family farms are backward and unproductive, research shows that small farms are much more productive than large farms if total output is considered rather than yield from a single crop [1].

The aim of this paper was to compare yield and breadmaking quality parameters of conventionally and organically grown winter wheat, and to determine the production potential and quality of organically grown wheat.

MATERIALS AND METHODS

A long term experiment with winter wheat grown at two different test sites, in conventional and organic agricultural practice started in 2007/08 growing season. At the same conventional and organic test site wheat will be grown again after several (if possible 7) years of crop rotation, and effects of soil improvement, as well as grain yield, bread making and nutritive quality, will be studied. Also the economics – cost of wheat unit produced by conventional and organic practice, will be calculated.

At Križevci, in one season (2008/09) eleven wheat genotypes (3 cultivars: Divana, Koleda, Renan, and 8 breeding lines: J801‐1, J801‐2, J801‐10, J801‐35, J802‐12, J802‐24, J803‐22 and J803‐37) were grown in an experiment of 5 square meters plots, in randomized block design, at two separate locations/cropping systems ‐ conventional and organic. The soil at conventional test site was very acid (pH = 4.21), with low organic matter (1.5%), but rich in P2O5 (28.7 mg/100 g) and K2O (17.7 mg/100 g), while the soil at organic test site was mild acid (pH = 6.25), with moderate organic matter (2.57%), very poor in P2O5 (3.4 mg/100 g) and moderate in K2O (10.0 mg/100 g). Applied agrotechnics for both test sites are presented in Table 1.

Table 1. Agrotechnics applied

Conventional Organic Preseeding crop: Fertilization – pure elements Herbicide Insecticide Fungicide

Corn for grain N 145 kg/ha P2O5 80 kg/ha K2O 120 kg/ha Cougar 1.8 l/ha Chromorel D 0.5 l/ha Bavistin 0.3 l/ha and Tilt CB 2 l/ha

Lupinus albus ‐ N‐fixing legume crop for green manure Stone powder (Ekorast) 500 kg/ha mechanical weeding none none


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After harvest standard analytical methods were applied and results are presented in Tables and Figures.

RESULTS AND DISCUSSION

Preliminary results of the first year are reported. The growing season 2007/08 was characterized with very dry winter and early spring. So needed rain came at grain filling stage (end of May). As consequence of dry soil, at conventional test site mineral fertilizers were not dissolved and nitrogen was not accessible to plant at tillering and steam elongation phases. The opposite situation was at organic test site: N fixed at roots of green manure crop (Lupinus albus) was on disposal to growing wheat plants. As a result, the average plant height was significantly higher in organic grown wheat (diff. = 9 cm). Also tillering was much better, and as result the average number of heads per square meter was significantly higher (diff. = 493). Finally, the average grain yield of organically grown wheat was also for 1.104 t/ha or 16% higher than yield of conventionally grown wheat. This was a real surprise. In test weight and thousand kernel weight there were no significant difference between the two different agricultural practices compared (Table 2).

In contrast to degraded, depleted and hyper acid soil of conventional test site, with poor microbial activity, the soil at organic test site is full of life (earthworms, large myriapods, snails, pot worms, springtails, mites, nematodes and microbes). Organic soil is literally alive with a network complexity greater than that if human brain tissue [2]. Soil in the immediate vicinity of plant roots is influenced profoundly by root‐derived nutrients and microbial activity. The predominant organisms in this region are the vesicular‐aebuscular mycorrhizal (VAM) fungi, having their greatest impact when plants are exposed to growth‐limiting environmental stress [3]. The studies also suggested that VAM improve the drought resistance of plants [4, 3]. Green manures not only provides a readily available source of nutrients for the growing crop, but also increases soil organic matter, and hence water retentive capacity [5], which was very important in this growing season.


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Table 2. Average yield components and grain yields of eleven wheat genotypes grown in conventional and organic practice

Practice Plant height cm

Heads per sqm

Yield t/ha

Test weight kg/hl

TKW g

Conventional 92 742 6.854 80.92 42.35 Organic 101 1235 7.958 80.44 43.20 Difference

9 **

493 ** 66 %

1.104 ** 16 %

‐ 0.48 NS

0.85 NS

** Difference significant at P=0.01, NS ‐ not significant

G x AE interaction ‐ Agricultural sustainability emphasizes the potential dividends that can come from making the best use of the genotypes (G) of crops and the agro‐ecological (AE) conditions under which crops are grown or raised [5]. Based on the results of G x AE interaction (the yield difference of a genotype between conventional and organic practice) we can choose most suitable cultivar for organic agriculture. In this experiment the largest yield improvement was recorded at cv. Divana (1.818 t/ha), while the smallest at cv. Renan (0.486 t/ha). According to this data it is possible to conclude that cv. Divana is more suitable for organic and cv. Renan for conventional agricultural practice.

Rheological parameters of wheat grown in conventional and organic practice

Beside grain yield, the bread making quality parameters are important. As well as grain yield of organically grown wheat was a positive surprise, the results of the rheological tests were disappointing. Organically grown wheat has proved to be less suitable for bread making industry (Table 3). We know that yield and quality parameters are in negative relation. But in this particular case the reason for mentioned difference is not the grain yield, but poor N supply in grain feeling stage. Beside N‐fixed by preseeding legume crop, organic test site did not get any additional amount of N‐fertilizer, while due to lack of rainfall, all applied synthetic N‐fertilizer become available to conventionally grown wheat right in grain feeling stage – the stage most responsible for grain quality formation.


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CONVENTIONAL yield: 5.175 t/ha; qual. gr. A1

ORGANIC yield: 6.993 t/ha; qual. gr. A2

Figure 1. Cultivar DIVANA ‐ rheological parameters


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CONVENTIONAL yield: 7.650 t/ha; qual. gr. A2

ORGANIC yield: 8.136 t/ha; qual. gr. B1

Figure 2. Cultivar RENAN ‐ rheological parameters


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It is obvious, if we would like to keep high quality in organic practice, additional foliar application with organic N in heading is necessary, and we will keep this in mind for the following experiment.

Table 3. Average rheological parameters of eleven wheat genotypes grown in conventional and organic practice

Quality parameters Conventional Organic Difference Protein content (%) 14.4 11.7 ‐2.7 Wet gluten (%) 32.5 25.0 ‐7.5

FARINOGRAPH Water absorption (%) 66.9 66.2 ‐0.7 Development time (min) 3.3 2.4 ‐0.9 Stability (min) 4.0 1.3 ‐2.7 Resistance (min) 7.3 3.6 ‐3.7 Degree of softening (BU) 34 66 32 Quality number 79.1 66.2 ‐12.9 Quality group A1‐A2 A2‐B2

EXTENSOGRAPH A Energy (sq cm ) 85.0 57.1 ‐27.9 B Extensibility (mm) 150 137 ‐13 C Resistance (EU) 296 238 ‐58 D Max. resistance (EU) 449 334 ‐115 Proportion C/B 2.00 1.73 ‐0.29 Proportion D/B 3.00 2.43 ‐0.57

AMYLOGRAPH Max. viscosity AU 1340 1246 ‐94

CONCLUSIONS

A common, though erroneous, assumption about agricultural sustainability is that it implies a net reduction in input use, thus making such systems essentially extensive. There are likely to be many pathways toward agricultural sustainability, and further implies that no single configuration of technologies, inputs, and ecological management is more likely to be widely applicable than another [5]. It was shown that, if all prerequisite for good yield are fulfilled, organic wheat production could be competitive with conventional. However, in the future more research is needed in this direction.


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REFERENCES

1. Altieiri, A.M. 2009. Agroecology, small farms and food sovereignty. Monthly Review, July‐August. http://www.monthlyreview.org/090810altieri.php

2. Warshall, P. 2002. Tilth and technology – The industrial redesign of our nationʹs soils. In: Kimbrell A. (Ed.) Fatal harvest – The tragedy of industrial agriculture. Island Press, pp. 221‐226.

3. Sylvia, D.M. and S.E. Williams. 1992. Vesicular‐Arbuscular micorrhizae and environmental stress. In: G.J. Bethlenfalvay and r.g. Linderman. Micorrhizae in sustainable agriculture. ASA Special publication No. 54, p.p. 101‐124.

4. Fitter, A.H. 1986. Effect of benomyl on leaf phosporus concentration in alpine grasslands: A test of mycorrhizal benefit. New Phytol. 103:767‐776.

5. Pretty, J. 2009. Can Ecological Agriculture Feed Nine Billion People? Monthly Review, Nov. http://www.monthlyreview.org/091123pretty.php

yield and quality parameters in · pdf file03.09.2010 · 5th international congress...

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