Identification of Resistance Sources in Wheat to Brown and Yellow Rust

W (Triticum aestivum L.) is an important crop and staple food for the people of Pakistan. It contributes 34% to GDP (Anonymous, 2015). During recent studies, it has been reported that 100g of edible portion of wheat grains contain 11.50% proteins, 59.40% carbohydrates, 9.70% fats, 10.60% crude fibers and 1.80% ash (Agarwal et al., 2005). In Pakistan, wheat ranked first as staple food followed by rice and maize. The cultivated area of wheat has been recorded 8.49 million ha with production of 23.52 million tons (Anonymous, 2015). This alarming gap between ever increasing demand and current production is a big challenge for all plant scientists. This challenge can be met over by increasing: (a) area under production, (b) yield per unit area and (c) minimizing the production losses. Increasing area seems almost impossible because of constraints like drought, salinity, water logging and trends in urbanization. The wheat crop is attacked by many diseases, of which rusts are of great importance. There are three types of rusts which are found on wheat. Leaf rust or brown rust is caused by Puccinia recondita f.sp. tritici while stripe rust or yellow rust is caused by Puccinia striiformis f. sp. tritici and stem rust or black rust is caused by Puccinia graminis f. sp. tritici. Leaf and stripe rusts appear periodically on wheat crop and induce heavy losses in yield (Kolmer et al., 2009). Leaf rust or brown rust of wheat is a serious production hazard in wheat all over the world and is an air-borne foliar disease on which early maturing wheat cultivars largely escape serious rust damage. Round to oblong, brick-red pustules (uredia) appear on leaves, stems Abstract | Current research was depicted the level of resistance among the available wheat germplasm in Pakistan against the deadly rust disease. 152 lines of the wheat were screened against brown and yellow rust of wheat which are a serious pathosystem of wheat throughout the world. Some varieties were found resistant some were found moderately resistant while some were in susceptible response against the both rust disease. No variety was found to be resistant at all against the rust pathosystems. Correspondingly, in the results of yellow rust some varieties were found resistant and some were found to be the most susceptible on the record. The epidemiological studies showed the correlation of the relative humidity of morning, evening and temperature positively in both of the rust disease. Fungicidal application showed great reduction in the management of the disease. Ateeq ur Rehman1, Syed Atif Hasan Naqvi1*, Ummad-ud-Din Umar1, Muhammad Irfan Zafar1, Faqeer Hussain2, Muhammad Asif Zulfiqar3 and Azhar Ali Khan3

and later on heads.As the crop ripens, black spores (telia) are produced.Similarly, stripe rust or yellow rust, is one of the most common fungal diseases of bread wheat in many countries because it is also an air borne disease.In the same way oblong, brick red pustules (uredia) appear on leaves, stems and later on heads and as crop ripens the black spores are produced (Hafiz, 1986).Hussain (1989) reported the occurrence of race one hundred and four Puccinia recondita f. sp.Tritici of which three pathotypes were distinguished.However, the new race was unable to overcome the resistance gene Lr13 and Lr26 most probably occurring in Pakistan cultivars.Environmental conditions play an important role in the development of the disease.Khan (1985) studied fifteen varieties of Wheat genotypes on slow rusting response in relation to environmental factors on these varieties.Different varieties showed slow rusting response at 77-78% R.H, 22-28 °C maximum temperature and 16-18 °C minimum temperature.Keeping in view the above facts regarding the rust diseases of the wheat the current research was planned to evaluate the collection of resistant sources against the rust disease of wheat and to determine the conducive environmental variable facilitating the disease in the field.

Establishment of rust screening nursery
Seeds of 152 genotypes were collected from the Ayub agriculture research institute (AARI) Faisalabad.Nursery was sown in area of wheat research institute (WRI) of ARRI.Nursery was sown in normal wheat season in experimental area.Line sowing 3m was done with R×R = 30cm.In order to maintain crop health and vigor agronomic practices were followed to keep the crop in good condition.

Artificial inoculation of wheat plants
Artificial inoculation was done by spraying urediospore suspension (30 gram of spore/16 liter of water).After every 5th line/variety a line of highly susceptible wheat cultivar i.e.Morocco, was sown to act as rust spreader row.(Morocco is highly susceptible to all the prevalent rust races and provides a substrate for rapid multiplication and distribution of rust inoculums).The nursery was also surrounded by sowing two rows of morocco to increase the inoculums pressure.

Data collection
Leaf and Stripe rust reaction, symbol field response and response value were recorded by the modified Cobb's scale described by Peterson et al. (1948).Disease severity was recorded after seven days' interval.Rust data were recorded up to physiological maturity of the wheat.The disease severity data was for leaf and stripe rusts was converted into coefficient of infection by multiplying severity with constant value for field response as described by Stubbs et al. (1981) and Raelf et al. (1992).Cobb's scale (Peterson et al., 1948) was used to record the rust severity data (Table 1).

Meteorological data collection
Environmental data consisting of maximum and minimum air temperature, relative humidity and sunshine were recorded by conventional instruments installed in meteorological section of Ayub agriculture research institute Faisalabad.

Fungicidal management
Different chemicals were applied to evaluate the efficiency of chemicals in controlling the rust diseases.Susceptible variety MORROCO was selected for this purpose.Trial was conducted at experimental area of Ayub Agricultural Research Institute (AARI), Faisalabad.Fungicides were applied between leaf emergence and booting stages.Three chemicals, Tilt, Myco-guard and Score were evaluated at 200mL/10L, 125 ml/10 L and 125mL/10 L the recommended dose concentration respectively.Trial was conducted in Randomize Complete Block Design (RCBD) with three replications.Data was analyzed statistically to determine the effectiveness of fungicides at 5% least significant difference using appropriate statistical tools.

Statistical analysis
All the collected datasets were subjected to analysis of variance by using SAS Carry Inc. 8.1 USA to determine the level of variability among the various genotypes through new Duncan's multiple range tests.3).

Relationship of environmental variables with disease severity of leaf rust and stripe rust
Effect of maximum temperature on leaf rust: The correlation of maximum temperature with leaf rust infection was found to be positive in all five genotypes/varieties.There was increasing trend in leaf rust disease development with maximum air temperature.The data shows that the disease severity increase with the increase in Temperature in varieties MANTHAR, MAXPAL 65, SHALIMAR 88, MOROCCO and LR-30 (Figure 1).

Effect of minimum temperature on leaf rust:
The correlation of minimum temperature with leaf rust infection was found to be positive in all five genotypes/ varieties.There was increasing trend in leaf rust disease development with minimum air temperature.The data shows that the disease severity increase with the increase in Temperature in varieties MANTHAR, MAXPAL 65, SHALIMAR 88, MOROCCO and LR-30.(Figure 2).

Effect of relative humidity on leaf rust:
The correlation of relative humidity with leaf rust infection was found to be positive in all five genotypes/varieties.There was increasing trend in leaf rust disease development with relative humidity.The data shows that the disease severity increase with the increase in Temperature in varieties MANTHAR, MAXPAL 65, SHALIMAR 88, MOROCCO and LR-30 (Figure 3).

Effect of rain fall on leaf rust:
The correlation of rain fall with leaf rust infection was found to be negative in all five genotypes/varieties.There was decreasing trend in leaf rust disease development with rain fall.
The data shows that the disease severity decrease with the increase in rain fall in varieties MANTHAR, MAXP AL 65, SHALIMAR 88, MOROCCO and LR-30 (Figure 4).

Effect of maximum temperature on stripe rust:
The correlation of maximum temperature with leaf rust infection was found to be positive in all five genotypes/varieties.There was increasing trend in leaf rust disease development with maximum air temperature.The data shows that the disease severity increase with the increase in Temperature in varieties C H A N NA B -2 0 0 0 , G A -2 0 0 2 , M A N T H A R , ROHTAS 90 and SARSABZ (Figure 5).

Effect of minimum temperature on stripe rust:
The correlation of minimum temperature with leaf rust infection was found to be positive in all five genotypes/varieties.There was increasing trend in leaf rust disease development with minimum air temperature.The data shows that the disease severity increase with the increase in Temperature in varieties CHANNAB-2000, GA-2002, MANTHAR, ROHTAS 90 and SARSABZ (Figure 6).

Effect of relative humidity on stripe rust:
The correlation of relative humidity with leaf rust infection was found to be positive in all five genotypes/varieties.There was increasing trend in leaf rust disease development with relative humidity.The data shows that the disease severity increase with the increase in Temperature in varieties CHANNAB-2000, GA-2002, MANTHAR, ROHTAS 90 and SARSABZ (Figure 7).

Effect of rain fall on stripe rust:
The correlation of rain fall with leaf rust infection was found to be negative in all five genotypes/varieties.There was decreasing trend in leaf rust disease development with rain fall.The data shows that the disease severity decrease with the increase in rain fall in varieties CHANNAB-2000,GA-2002, MANTHAR, ROHTAS 90 and SARSABZ (Figure 8).

Chemical control of brown rust and yellow rust:
At the start of the experiment when no treatment was applied the value of mean disease severity was 40.After three days' mean disease severity was reduced in those blocks where fungicides were applied and in the block of control.Values remain constant which was 40.After 7 days and 10 days' mean disease severity was also calculated (Table 4, Figure 9, Table 5, Figure 10).
Plant diseases are a great threat to plants, in such that fungal diseases facade a potential threat to successful cereal production in general and particularly wheat in Pakistan.Wheat is a staple food for the people of Pakistan so the rust diseases are of too economic      that out of 188 cultivars, 150 responded with RRI value ≥7 ≤9 and were found in the desirable range; 28 cultivars were included among the acceptable range having RRI value ≥5 ≤ 7.However, only 10 cultivars showed RRI value <5 and were placed under undesirable range.Ahmad et al. (2010) screened thirty six genotypes against yellow rust to check their level of susceptibility or resistance.Among these, 18 were susceptible, 6 were moderately susceptible to susceptible, 7 were moderately resistant to moderately susceptible and 5 genotypes remained resistant.Minimum temperature and relative humidity remained positively correlated while the maximum temperature showed negative correlation with stripe rust severity.With the rise of minimum temperature and relative humidity a rise up in stripe rust infection was seen while as the maximum temperature rise stripe rust infection decreased on different genotypes.From this study it may be concluded that epidemiological factors played important role in the dispersion of the disease which resulted in yield losses.

Figure 1 :
Figure 1: Relationship between maximum temperature and Leaf rust for varieties.

Figure 2 :
Figure 2: Relationship between minimum temperature and Leaf rust for varieties.

Figure 3 :
Figure 3: Relationship between relative humidity and Leaf rust for varieties.

Figure 4 :
Figure 4: Relationship between rain fall and Leaf rust for varieties.

Figure 5 :
Figure 5: Relationship between maximum temperature and Yellow rust for varieties.

Figure 6 :
Figure 6: Relationship between minimum temperature and Yellow rust for varieties.importance for Pakistan because they pose a serious threat to the wheat production.During the current research all the varieties showed a varying response regarding the development of disease with moderately resistant to highly susceptible.Yet it is too alarming that no variety is resistant against the rust pathogen in Pakistan.Afzal et al. (2009) during 2005-2007, carried out variability for field based partial resistance

Figure 7 :
Figure 7: Relationship between relative humidity and Yellow rust for varieties.

Figure 8 :
Figure 8: Relationship between rain fall and Yellow rust for varieties.against stripe rust among 188 wheat breeding lines grown at the experimental area of the PMAS Arid Agriculture University, Rawalpindi, along with Morocco as susceptible check.The wheat lines and commercial varieties were screened out under natural climatic conditions of arid zone of Pakistan.Average Coefficient of Infection (ACI) and Relative Resistance Index (RRI) values of two year trial showed

Figure 9 :
Figure 9: Relationship of disease severity reduction of brown rust with days.

Figure 10 :
Figure 10: Relationship of disease severity reduction of yellow rust with days.
Wheat yield lost due to varying level of yellow rust Identification of resistance sources in wheat March 2019 | Volume 32 | Issue 1 | Page 195

Table 1 :
Leaf and Yellow rust reaction, symbol field response and response value.

Table 2 :
Response of different genotypes against leaf or brown rust of wheat.

Table 3 :
Response of different genotypes against stripe or yellow rust of wheat.

Table 4 :
Effect of different treatments on the disease severity of brown rust.