The rice situation in Iran¹

N. Shobha Rani

Directorate of Rice Research, Rajendranagar, Hyderabad, 500 030 India

The Islamic Republic of Iran is a vast country, covering 1 648 000 km² and located between latitudes 25° and 40°N and longitudes 44° and 63°E. The country is dominated by two mountain ranges - Elburg and Zagros - while two great deserts extend over much of the central region, leaving about 20 million ha for crop production.

On account of the highly diverse climatic and soil conditions, only 12.5 million ha are cultivated annually with a wide range of food crops. Wheat, rice and barley are the most important cereals cultivated.

RICE SCENARIO

Rice is the staple food in Iran, with the quality of cooked rice outweighing all other considerations for Iranian consumers. The total area under rice is more than 600 000 ha and rice is grown in 15 provinces. However, more than 80 percent of rice area is distributed in the two northern provinces of Mazandaran and Gilan. It is estimated that 265 000 ha those in Mazandaran (including areas in Gorgan) and 230 000 ha in Gilan are under rice cultivation. The monthly temperatures and rainfall of Gilan - which are similar to those of Mazandaran - during the rice-growing season vary from 19° to 25°C and 25 to 125 mm, respectively. From 1.8 million tonnes in the late 1980s, rice production in Iran increased to 2.36 million tonnes in 1991 and 2.65 million tonnes in 1993, with the average yield being 3 780 kg/ha (rough rice). The per caput consumption of rice is around 28 kg per caput/year. As the demand and supply of rice in Iran are still not evenly balanced, the country imports around 400 000 to 500 000 tonnes of rice for domestic consumption (Fig.).

Figure: The rice situation in Iran - production, supply and imports

Almost all rice is grown under irrigated conditions in normal soils (pH 7.0-7.5) and yields are high, at 3 to 3.5 tonnes/ha for local and 5 to 7 tonnes/ha for improved varieties. Normally one crop of rice is taken from April/May to August/September with 100- to 130-day varieties, with the appropriate duration being 110 to 125 days. Some areas in Gilan and Mazandaran Provinces are suitable for producing a second crop, but careful thought needs to be given to whether a short-duration rice crop or a ratoon crop is better or, alternatively, whether another cropping pattern might be more profitable for farmers.

Drought is a problem in specific areas of certain southern provinces, while 200 000 to 300 000 ha in Mazandaran and Khuzistan are affected by salinity. The government at present is making determined efforts to bring in land consolidation at the rate of 1 000 ha per year in order to introduce farm mechanization.

The most important research priorities in Iran are breeding for high-yielding, quality rices and stabilizing yields through the incorporation of genes for resistance to blast, which is the major disease - bakanae disease, sheath blight and sheath rot are of minor importance. Research on stem borer is focused on biological control, and has shown so far that 80 percent control can be achieved in farmers' fields with the release of Trichogramma in floodwater. The Rice Research Institute of Iran (RRII), located at Rasht in Gilan Province, together with its affiliate in Amol in Mazandaran, is making a concerted effort to increase productivity per unit area so as to attain self-sufficiency. There is further scope for increasing area under rice in the southern provinces, which would raise rice production overall of Iran.

VARIETAL STATUS

Despite the low yields of local varieties (averaging 2.5 to 3.5 tonnes/ha), because of their excellent quality traits, more than 80 percent of the total rice area in Iran is still under these varieties, which are similar to basmati types and are characterized by tall stature (125 to 135 cm), a weak culm and droopy leaves. They have a long slender grain and a head rice recovery (HRR) of 60 to 63 percent, an intermediate amylose content (AC), aroma and elongation qualities. They are prone to lodging and are also susceptible to blast and stem borer. The most popularly grown local varieties are Hasan sarai, Domsiah, Binam, Hasani, Salari, Ambarboo and Sang tarom (Table 1).

The primary classification of Iranian rices is based on physical grain shape and market value. They are broadly classified into three categories by grain and shape:

i) Sadri: very long slender grain; >7 mm kernel length; superior cooking and eating qualities; aromatic; high grain elongation; susceptibility to blast and stem borer; average yield about 5 tonnes/ha. These rices sell in the market at a very high price of 400 tomans or more than US$1/kg.

ii) Champa: medium grain; smaller kernel and lower market value than the Sadri category but more resistant to environmental stresses, diseases and insects; higher yield than the Sadri group.

iii) Gerdeh: short and round grain; much lower market value but more resistant and higher yielding than the first two categories.

RESEARCH EFFORTS

Since the 1960s, research has been carried out on all aspects of rice agronomic practices related to seed rate, date of sowing, spacing, plant density, fertilizer schedule, pests and diseases and weed management practices. The varietal improvement projects have mainly concentrated on improving the local varieties through mass selection and hybridization, followed by the pedigree method and mutation breeding. Until the 1990s, these studies were scattered attempts among several of Iran's discipline-oriented research institutions.

However, for the purpose of unifying these disparate activities, RRII was established in 1993. The main focus of the new centre is the promotion of research related to the development of high-yielding rice varieties that are resistant to diseases and pests; modern techniques for increasing domestic rice production; and the implementation of research projects on farm mechanization, tillage systems and post-harvest technology.

The disciplines at RRII, in Rasht and Amol, are:
i) plant breeding; ii) pest, disease and weed control;
iii) water and soil science; and iv) agricultural engi-neering. Important activities include:

Plant breeding

• Evaluation of INGER nurseries;
• pedigree breeding method for improving grain quality;
• use of mutation tool for selective rectification of defects in high-quality local types;
• development of hybrid rice technology;
• evaluation of IRRI basmati lines;
• genetic studies of quantitative and quality traits by use of mating systems such as diallel mating;
• correlation and path analysis for yield and its components;
• estimating the extent of variability and heritability for grain yield and its components;
• evaluation of Iranian germplasm for yield, quality and pest disease reaction;
• characterizing Iranian germplasm using biochemical markers;
• production of dihaploid pure lines from F₁s through anther culture;
• mapping genes that control grain quality traits so as to allow the development of marker-assisted selection methods;
• studies on grain quality of traditional Iranian cultivars, including the effect of ageing, processing and the environment on quality parameters.

Plant pathology, entomology and weed control

• Studies on biological agents controlling bakanae disease in rice-fields;
• studies on control of rice blast with fungicides;
• testing the efficiency of new fungicides for seed treatment to control bakanae disease;
• studies on Trichogramma for controlling stem borer (Chilo suppressalis) in rice in Gilan and Mazandaran Provinces;
• studying the synthetic sex pheromone for mating disruption in stem borer;
• evaluation of new herbicides in rice-fields;
• studies on sheath blight variation and biological control using either Trichoderma spp. or antagonistic bacteria (Pseudomonas spp.);
• evaluation of resistance of native and improved rice varieties to stem rot disease in Gilan and Mazandaran Provinces;
• investigation of effective factors in increasing resistance of rice cultivars to stem borer;
• studying the effect of potassium on yield and blast disease infection in Mazandaran Province.

Agronomy and soil science

• Studying the effect of planting date and spacing on yield and quality parameters;
• determining the nitrogen requirement for IRRI basmati lines;
• crop growth analysis;
• identification of early-maturing varieties for double cropping;
• experiments on lock lodging to study the feasibility of raising second rice crops by ratooning;
• studying the uptake pattern of macronutrients during different stages of rice plant growth;
• identifying associated N₂-fixing bacteria isolated from the rice rhizosphere and determining nitrogen efficiency by the ARA method;
• long-term evaluation of the cumulative effect of chemical fertilizer application on the fertility of paddy soils;
• studying the effect of zinc on rice yields in continuously flooded soils;
• evaluation of potassium status by modified Q/L and buffering power in Gilan paddy soils;
• studies on sowing density in seedling boxes for transplanting through machines;
• comparing the application of sprinkler and submerged irrigation for direct seeded and transplanted rice;
• long-term experiments on the NPKS and Zn supplying capacity of soils for rice cultivation.

RESEARCH IN VARIETAL IMPROVEMENT

Hybridization breeding programmes have been aimed at improving the yield of local varieties and developing high-yielding varieties (HYVs) with desirable cooking and eating quality traits. At Rasht and Amol in the 1980s, several HYVs were developed (Table 2) with a high yield potential, ranging from 5 to 7 tonnes/ha, and a high degree of resistance to blast. About 60 000 ha in Mazandaran Province, which has about one-third of the total rice land in Iran, were planted to Amol 2 and Amol 3. Gradually they are being replaced by Khazar and Sepeed rood. In Gilan, Gil 1 and Gil 3 were the major varieties planted but Khazar, Sepeed rood and Bejar now occupy most of the area under HYVs. Except for Khazar and Gil 3, however, all these varieties lack aroma and have a high amylose content. As the Iranian market is dominated by aromatic rices that are flaky and soft when cooked, in spite of their high yield advantage, these varieties fetch a lower price than the traditional local types. Nemat, a newly released variety with high yield potential (>7 tonnes/ha) with a mild aroma and good grain quality, coupled with resistance to blast and tolerance to stem borer, is believed to have been planted to 13 000 ha in 1996 and may replace some of the traditional local types. Neda, another promising culture, also compares well with Nemat and covers 20 000 ha in Mazandaran Province. Dasht is another variety, with a yield of 6.5 to 7 tonnes/ha and resistance to blast, which occupied about 10 000 ha in 1996. Two IRRI basmati lines, IR62871-264-3-4 and IR62871-75-1-10, have been extensively tested over the last three years. They may be suitable and are likely to be released on account of their high yield (6.5 to 7.5 tonnes/ha) and desirable quality characters.

Reducing the plant height of Mosa tarom (198 to 97 cm), its susceptibility to blast (from 9 to 4 or 5) and days to maturity from (132 to 117 days) as well as reducing days to maturity in Amol 3 are some of the objectives strongly pursued through gamma irradiation methods. An important project is under way to characterize the valuable Iranian rices using isozyme markers. Attempts are being made to develop rice hybrids following the three-line approach, but further support is needed in this area. Several studies on the genetics of quality, increased yields and agronomic traits are being studied by selective mating systems.

But most important is the collaborative study initiated under the IRRI-IRAN project which was successful in cloning and synthesizing the STS markers and RFLP markers to the aroma gene, which is a commendable achievement. Using bulk segregant analysis, material is being built up to identify RAPD markers linked to the blast resistant gene, which is yet another project planned with IRRI's technical cooperation. A double dose of the BT gene has been introduced in Tarom and Khazar through ballistic bombardment, and a large area in Mazandaran (18 000 ha) and Gilan (10 000 ha) Provinces use Trichogramma to control stem borer biologically.

PROBLEM SOLVING

Iranian rice production would benefit from:

• the development of HYVs with superior grain quality of early and medium maturity groups, resistant to blast and tolerant of stem borer - such varieties could replace the traditional low-yielding local types, thereby stepping up overall rice production and productivity in the country;
• suitable varieties tolerant of drought and salinity - such varieties would enable higher productivity in problem areas;
• the possibility of raising a second rice crop in areas where it is feasible;
• better extension backup to increase the area under HYVs.

The methods that are being followed to overcome the first point mentioned above (the need for improved HYVs) are:

• the pedigree breeding method;
• mutation breeding;
• hybrid rice technology; and
• using biochemical and molecular markers to determine the linkage groups controlling grain quality traits and eventually to develop marker-assisted selection (MAS) methods.

Considerable progress has been achieved in developing HYVs by the pedigree method, as outlined above. Were it not for their lack of certain desirable quality traits, including aroma, HYVs would have replaced the local varieties over a considerable area in both provinces. However, owing to poor consumer acceptance at present, the area under HYVs is estimated to be only about 20 to 25 percent. Mutation breeding and hybrid rice technology have yet to produce findings that can be applied at the field level, while the collaborative studies under the IRRI-IRAN project on marker-assisted selection for quality traits is in the process of development, so the application of such innovative techniques will take a few more years.

Although development of HYVs that have superior grain quality and are of early and medium maturity groups is the main objective, the parental materials used in crossing are not altogether the best quality donors. The parentage of Gil 1, Gil 3, Khazar, Sepeed rood, Bejar, Dasht and a few others (Table 3) as well as IR5, IR8, IR28, IR29, IR498 and the sister line of IR36, which do not possess desirable quality traits (Table 4), have been used as one of the parents, although the other parents are quality rices of Iran. All the IR varieties used have a high amylose content (AC) and IR29 is waxy as well. Varieties with a high amylose content cook dry, are less tender and become hard on cooling. Waxy rices, which have almost no amylose, become sticky and glossy on cooking. When the preference in Iran is for a long grain, intermediate amylose types with aroma and direct single crosses may not be the answer. Only IR36 is somewhat acceptable because of its intermediate gelatinization temperature (GT) and high amylose content but medium gel consistency (GC). The sister line of IR36 might have a soft gel consistency; hence Khazar, a derivative of the IR36 sister line/TNAU 7456, is the only variety with the best combination of traits (intermediate/medium amylose content, intermediate gelatinization temperature and a soft gel consistency. Since it also has a high yield potential, it has gained considerable acceptance among farmers as well as consumers, although caution must be exercised in selecting the parental materials.

Recommendations

i) There is a need to widen the genetic base. Although most Iranian rices are endowed with the best mix of quality traits, quality dwarf and tall rices from countries such as India, Thailand, Pakistan, the Philippines, INGER nurseries and IRRI basmati lines should be evaluated and utilized. Sterility problems, which are normally encountered when aromatic types are crossed with other groups of rice types, may not be a barrier with the availability of the wide compatibility (WC) gene in different genetic backgrounds. Convergent breeding, which aims at converging genes from diverse sources into a single hybrid, would be more useful. Three-way, double- and backcrosses and intermating between two F₂ populations of single crosses to increase the frequency of useful recom-binants should also be attempted.

ii) A priori selection may not work, as the quality of rice cannot be judged by assessing the plant stature, agronomic and yield components. Donors and parental lines (in the case of a hybrid programme) must be screened for major quality traits and for blast resistance in uniform blast nurseries.

iii) Parental selection must either be on the basis of parental performance or according to methods that evaluate the parent on the basis of its progeny. Studies are being done on genetic action, combining ability for yield and quality characteristics and generation mean analysis. If parental selection is based on the results of such studies, including screening, it should be possible to isolate better and useful recombinants that combine both yield and quality.

iv) Since quality is the single most important factor in Iran, laboratories must first be strengthened at Rasht and Amol with the full involvement of a breeder and a cereal chemist. This is very important, as Iran is also attempting to develop hybrids. And experience (e.g. in India) shows that the reason for non-acceptance of hybrid varieties is their inadequate quality.

v) The exchange of local and improved germplasm with other countries with similar programmes must be encouraged. A highly successful breeding programme is one where the genetic diversity of experimental materials is sustained, thereby minimizing the genetic vulnerability that is inherent in the cultivation of uniform and closely related cultures over wide areas. The vast collection of quality rices available in Iran must be evaluated for agromorphological and quality parameters and disease resistance - especially to blast - although a large project to characterize these rices based on isozyme markers is under way.

vi) Iran has explored the possibilities of using DNA markers to map genes for aroma and gelatinization temperature via bulk segregant analysis, and work is in progress in collaboration with IRRI on the identification of RAPD markers linked to blast-resistant genes. Such efforts should be continued, as these studies would help not only in understanding the complex nature of quality traits but also in aiding marker-assisted selection.

vii) Emphasis may be put on the development of aromatic hybrids with desirable quality traits, and advantage should be taken of the CMS and restorer lines already developed in other countries.

La situation du riz en Iran

Voici un extrait du rapport d'une mission de consultation de la FAO dans le cadre de la CTPD. Les Iraniens, pour qui le riz est la nourriture de base, s'intéressent tout particulièrement à la qualité du riz cuit. La superficie totale vouée au riz dépasse 600 000 ha; dans les 15 provinces où celui-ci est cultivé, ses rendements sont élevés allant de
3-3,5 tonnes à l'hectare pour les variétés traditionnelles et de
5-7 tonnes à l'hectare pour les variétés améliorées. La priorité absolue en matière de recherche est la sélection de riz à haut rendement et la stabilisation des rendements par incorporation de gènes de résistance à la pyriculariose, la maladie de Bakanie, au flétrissement et à la pourriture. L'Institut iranien de recherche sur le riz, situé à Rasht dans la province de Gilan, et son annexe à Amol, dans la province de Mazandaran, sont responsables de la recherche dans le pays. Les recommandations de la mission de consultation incluent la nécessité d'élargir la base génétique du riz en Iran, l'examen des résultats des lignées parentales pour l'amélioration variétale de la qualité et de la productivité, l'échange de matériel génétique avec des pays voisins comme l'Inde, le Pakistan, etc., un renforcement des travaux sur les marqueurs de l'ADN liés aux gènes de résistance à la pyriculariose en collaboration avec l'IRRI, et la mise au point d'hybrides aromatiques possédant de bonnes caractéristiques de qualité.

Situación del arroz en el Irán

A continuación se ofrece un resumen del informe de una misión de consulta de la FAO en el contexto de la cooperación técnica entre países en desarrollo. El arroz es el alimento básico de la población del Irán, siendo la calidad del arroz cocinado la consideración preponderante para los consumidores iraníes. La superficie total plantada de arroz es superior a 600 000 ha, el arroz se cultiva en 15 provincias y los rendimientos son elevados, estando comprendidos entre 3,0 y 3,5 toneladas/ha para las variedades tradicionales y entre 5,0 y 7,0 toneladas/ha para las variedades mejoradas. La máxima prioridad de la investigación es obtener arroz de calidad de alto rendimiento y estabilizar los rendimientos mediante la incorporación de genes para aumentar la resistencia al añublo, a la enfermedad de Bakanae, al tizón de la espata y a la marchitez de la vaina foliar. El Instituto de Investigación sobre el Arroz del Irán, que tiene su sede en Rasht, en la provincia de Gilán, y su subinstituto en Amol, Mazandarán, están encargados de las investigaciones sobre el arroz en el país. La misión de consulta formuló varias recomendaciones relativas, entre otras cosas, a la necesidad de ampliar la base genética del arroz en el Irán, el examen de los resultados de las líneas parentales para mejorar tanto la calidad como la productividad de las variedades, el intercambio de material genético con países vecinos como la India, Pakistán, etc., la intensificación de las actividades relacionadas con marcadores de ADN asociados a genes de resistencia al añublo, en colaboración con el IRRI, y la obtención de híbridos aromáticos con los rasgos de calidad deseados.

 ¹ Excerpt from the report of an FAO/TCDC Mission to the Islamic Republic of Iran.