IPI International Potash Institute
IPI International Potash Institute

Research Findings: e-ifc No. 15, March 2008

Research work from Argentina: Wheat varieties and management practices for disease control

Ferraris G.N., and L.A. Couretot1. An extract from the original, edited and translated by R. Melgar

(1)Exp. St. Pergamino INTA, Buenos Aires

Introduction
Some nutrients like chloride indirectly affect yields by increasing foliar area duration. This response to chloride can be likened to a fungistatic effect in a response to fungicide application. Several works have been conducted in the Pampas region of Argentina reporting the increase in wheat yields by applying chloride fertilizers. There are no detailed plant physiological explanations to account for this benefit so that the responses of increased yield may be considered in relation to chloride induced improved phytosanitary effects.

Table 1. Treatments applied in the wheat experiments for all wheat varieties.
Treatment KCl Fungicide
  (kg/ha)  
Check 0 0
KCl 100(1) 0
Fungicide 0 Kresoxim-metil 12.5% +
Epoxiconazole 12.5%(2)
KCl + Fungicide 100(1) Kresoxim-metil 12.5% +
Epoxiconazole 12.5%(2)
Fungicide X2 0 Kresoxim-metil 12.5% +
Epoxiconazole 12.5%(2)
Metconazole 9%(3)
Notes: (1) KCl was given at sowing; (2) Spray at Zadoks 39; (3) Spray at Zadoks 79.

The objective of this experiment was to generate information regarding the varietal behaviour of wheat and its interaction with disease management practices including fungicide control and chloride nutrition. The trial was conducted during the 2004 and 2005 season on a fertile and productive Typic Argiudol of Pergamino, under no tillage following soybean.

Eight wheat varieties from six different seed companies were tested: 1) PMol: Produsem Molinero; 2) A304: ACA 304; 3) B11: Nidera Baguette 11; 4) B10: Nidera Baguette 10; 5) BMat: Buck Mataco; 6) BGua: Buck Guapo; 7) RTij: Relmó INIA Tijetera and 8) Kcap: Klein Capricornio. Incidence of disease was evaluated on each plot, as well as grain yield at harvest.

The source of chloride was fertilizer KCl, and fungicides used were Kresoxim-metil and Epoxiconazole. The treatments are described in Table 1.

Results
On average for all cultivars, the application of fungicide significantly increased grain yield (Fig. 1), but one application at the physiological growth stage of 39 on the Zadoks scale (before flag leaf sheath extension) was sufficient, and there was no need for the second application at Zadoks 79 (anthesis). The application of KCl improved grain yield by 269 kg/ha (8.8%), and the combination of both KCl and fungicide did not further increase yield. However, grain yield of each cultivar responded differently to the two factors tested, namely the application of KCl, fungicide, and the combination between them.

Fig 1. Wheat yields in the various KCl and fungicide treatments (results are average of eight wheat varieties).
Fig 1. Wheat yields in the various KCl and fungicide treatments (results are average of eight wheat varieties).

The response of each cultivar to both KCl and fungicide application is described in Table 2. Clearly, some wheat cultivars responded well to both KCl and the different fungicide applications (varieties B11P, B10 and Bgua)) but with no significant interaction to either factor. Other cultivars responded well only to KCl (PMol) or fungicide (Rtij), while other varieties did not respond to KCl (A304, Bmat, Rtij and Kcap) or fungicide (Pmol, A304 and Kcap). On average, both KCl and fungicide contributed equally 8 per cent to grain yield.

Table 2: Effect of KCl and fungicide on eight wheat varieties.
Variety

 
Pmol A304 B11P B10 Bmat Bgua Rtij Kcap Mean
  kg/ha
Control 3,934
a
3,691
ab
4,022
a
3,347
bc
3,491
bc
2,756
de
3,142
cd
2,598
e
3,372
Additional yield with:                  
KCl(1) 1,056 78 300 344 67 467 -233 78 270
Fungicide(2) 67 39 239 478 228 617 689 -100 207
Notes: (1) average for treatments with and without fungicide; (2) average for treatments with and without KCl.

During the 2004/05 season, climatic conditions were good and wheat reached high productivity levels. Disease expression was low in severity and affected cultivars were those more sensitive to rust (Puccinia recóndita). In this scenario, there were significant differences between treatments. KCl and application of fungicides at the expanded flag leaf stage resulted in increased yields, whereas fungicide application at anthesis was not effective in controlling disease.

There were three varieties which responded well but interaction between variety and management practice were not statistically significant. However, different cultivars expressed some variability in response to different management strategies, dividing the cultivars between those of naturally high phytosanitary status, from those which responded to KCl or fungicide application.

Published in: Proyecto Agricola. Campaña 2004. Est. Exp. Agr. Pergamino INTA. 245 p. The full paper is available on-line.

Wheat: yield response to chloride fertilization on different cultivars and its effect on foliar disease severity

By J. Castellarín, H.M. Pedrol, L. Ortis, M.C. González, M. González, and O. Rosso. Exp. St. Oliveros INTA. Santa Fe. An extract from the original, edited and translated by R. Melgar.

The effect of fertilization with sulphur, potassium and chloride on plant health is clearly seen. The picture is from the IPI-INTA project 1998-2004 on Long-Term Effects of Fertilization with K, S, and Chloride in the Pampa region. Arecifes, Buenos Aires, 2001. Photo by IPI.
The effect of fertilization with sulphur, potassium and chloride on plant health is clearly seen. The picture is from the IPI-INTA project 1998-2004 on Long-Term Effects of Fertilization with K, S, and Chloride in the Pampa region. Arecifes, Buenos Aires, 2001. Photo by IPI.

An experiment was performed to study the yield response of wheat to KCl application and its effects on foliar disease severity in different varieties varying in phytosanitary behaviour. A field trial was conducted in Oliveros, Santa Fe province, evaluating grain yield and disease incidence on a factorial designed experiment with six wheat varieties, (Don Mario Onix, Baguette Premium 13, Baguette 11, ACA 304, Don Mario Cronox and INIA Sirirí), four levels of KCl (0, 30, 60 and 90 kg K2O/ha), with and without fungicide treatment (Pyraclostrobin, 133 g/l + epoxiconazole, 50 g/l).

Table 1: Incremental yield response due to KCl application in different wheat varieties.
Variety Yield Incremental yield
response for KCl
  NPS
control(1)
Average Maximum
  kg/ha %
Don Mario Onix 5,076 5.3 6.9
Baguette
Premium 13
4,349 9.4 12.6
Baguette 11 3,803 13.4 18.4
ACA 304 3,232 10.4 19.7
Don Mario
Cronox
3,164 9.7 13.1
INIA Sirirí 3,099 11.8 14.0
Notes:  (1)N=126; P2O5= 52; S=15 kg/ha.

Fig. 1 and Table 1 show that all tested wheat varieties differentially benefited from fungicide application (Fig. 1), and also from increased levels of KCl (Table 1). Yield response to KCl was on average increased between 5 to 13 per cent. However, at best it could reach even a 20 per cent yield increase. Except for Baguette 11, all other varieties responded best to the highest level of K applied (90 kg K2O/ha). On average, there was a significant yield response to KCl application, with best yield achieved with the high KCl rate (90 kg K2O/ha; Fig. 2). Response to KCl in some cultivars did not relate to foliar disease as measured by percentage of severity. However, the infection and the incidence of disease was rather low. The yield increase due to KCl differed according to the cultivar. Response to fungicide application varied depending on fertilization treatment. Increasing KCl rate resulted in a decreased response to fungicide.

Fig 1. Yield response of different wheat varieties to fungicide application.
Fig 1. Yield response of different wheat varieties to fungicide application.

Fig 2. Average yield response of different wheat varieties to KCl application. Significance at Duncan at 5% represented by different letters.
Fig 2. Average yield response of different wheat varieties to KCl application. Significance at Duncan at 5% represented by different letters.

Results suggest that fertilization with KCl, even at K levels in soil, as high as 1.3 meq/100 g soils, benefits yield of various wheat varieties and provides a promising alternative and complementary means of controlling foliar diseases in wheat.

Published in: TRIGO - Para Mejorar la Producción Nº 34 E.E.A. Oliveros INTA. pp. 38-42. Full paper on-line

Nutritional evolution of drip irrigated peach (Prunus persica L.) trees

By A. Bermejillo, V. Lipinski, M.F. Filippini, M. Venier, D. Cónsoli, and A. Valdés. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. An extract from the original, edited and translated by D. Kirschbaum.

Few studies have been made on the nutritional standards required for optimal production of fruit trees in the province of Mendoza, Argentina because of the complexity of the work and time required for these investigations.

This study describes the nutrient seasonal variations of peach trees during three to four production seasons (years 2002-2006) in two 7-year-old peach orchards in Villa Seca (Tunuyán), Mendoza.

The orchard in El Desafío was planted with the variety "Dr. Davis" and in El Porvenir the variety was "Heese". Both orchards are fertigated using a drip system and N, P, and K were applied via the fertigation system. Leaf samples were taken during the summer, twice weekly from a mean height of 1.5 m, taking the fourth leaf from the apex of each branch. These leaf samples were analysed for N, P, K, Ca, Mg, Fe, Mn, Zn and Cu and graphs describing changes in leaf nutrient status for each element were obtained. In this summary, only the graphs for K are presented.

Fig. 1. Potassium concentration in leaves of 'Dr. Davis' peaches
Fig. 1. Potassium concentration in leaves of "Dr. Davis" peaches

Fig. 2. Potassium concentration in leaves of 'Heese' peaches.
Fig. 2. Potassium concentration in leaves of "Heese" peaches.

According to the literature, values <1% are deficient, 1-1.9% are low, 2-3% are normal, 3.1-4% are high, and >4% very high.

For all years, in El Desafío, K values were relatively low (2%) at the beginning of the season (ca 2%), probably as a consequence of a naturally poor K content of the soil. Later, when fertigation was implemented, K values rose to 3% and remained stable more or less at this value during the rest of the season (except in 2003-04).

K contents in leaves at the El Porvenir site increased from year to year, possibly reflecting good K fertigation management.

It is important to note that fertilization with K is crucial at the end of the season in order to prevent K decreases to below critical values. In both locations, K is applied from December with the purpose of improving fruit quality.

In 2005-06, foliar K values were higher than usual in December and January probably because the fruit load this season was lower than in normal years.

This occurred either because of inclement climatic conditions early in the season, or improved K fertigation management of the orchard or both these factors.

Published in: Proceedings of the III Jornadas de Actualizacion en Riego y Fertirriego. 10-11 Aug 2006, Mendoza, Argentina. Full paper on-line

Seasonal variation pattern of nutrients in blueberry plants grown in the northern Buenos Aires province.

By Pescie, M.A., Lacarra, H. and Lopez, C.G. An extract from the original, edited and translated by D. Kirschbaum.

Experimental blueberry plantation in North Argentina. Photo by H. Magen, 2000.
Experimental blueberry plantation in North Argentina. Photo by H. Magen, 2000.

Blueberry is a species for which nutrient requirements have not been evaluated because it is native to sandy areas, where nutrient levels are low and supplied at a pH between 4 and 5. In Argentina, where blueberries are a relatively new crop, there is no information about its nutrient requirements. This study determined the seasonal variation of macronutrients (N, P, K, Ca, Mg, and Na) in two major varieties of southern highbush blueberry varieties (O'Neal and Misty). Mature leaves were collected in fruiting branches from the four cardinal points of healthy uniform 7-year-old plants, every 15-30 days (depending on the phenological phase of the crop), from the emergence of the first leaves to the end of the summer. Leaves were dried at 65°C. Nitrogen was determined by Micro-Kjeldahl and P by spectrophotometry. Other nutrients were determined by atomic absorption spectrophotometry. Both, N and P concentrations tended to diminish progressively until the end of the studied period, stabilizing after the end of harvest (December). Potassium increased slightly after harvest, remaining stable until the end of the study. Sodium and Mg contents remained stable throughout the entire growing season, while Ca increased until harvest, then decreased, and increased again at the end of the growing season. The period of highest stability of nutrients was January.

Published in: Horticultura Argentina. 2006. 25:86.