[en] Full text: Chickpea is the most important grain legume crop of Pakistan. Ascochyta blight (Ascochyta rabiei) and Fusarium wilt (Fusarium oxysporum F. sp cicer) are most serious diseases, having the potential to devastate a crop. A multiple disease resistant and high yielding mutant CM 88 has been developed through 100 Gy gamma irradiation treatment of variety 'C 727'. This was once a widely grown and popular variety, which lost its resistance to Ascochyta and was replaced. The selection of mutants was performed in the M2 generation grown in the Ascochyta blight nursery and sixteen mutants were selected. In the subsequent generations CM 88 proved resistant to both Ascochyta blight and Fusarium wilt, and exhibited superiority in agronomic characteristics. CM 88 was also tested for many years in the various yield trials on research stations and farmers fields throughout the country. In these trials it out yielded both the parent and standard varieties. The mutant CM 88 has been approved by the Punjab Seed Council on 27 October 1994 for general cultivation in the Punjab Province, especially the Thal area which accounts for more than 70% of the area under chickpea cultivation. (author)

[en] Blackgram (Vigna mungo L. Hepper) is an important pulse crop extensively grown in India. It is the cheapest source of protein for millions of Indians. The seeds contain about 22% protein. The area under cultivation in India is about 3.25 million hectares with an annual production of 1.45 million tons. About 70% of the total area is in the Central and Southern part of the country, which contributes about 77% of the total production. In the past there have been attempts to increase the production and productivity of this crop using conventional breeding approaches at different Agricultural Research Centres. However, the yield remains around 500 kg/ha. We have used induced mutation techniques to break the yield barrier. The induced mutations were used in cross breeding to synthesise an ideal plant type with high yield potential suitable for different agroclimatic conditions

[en] Seeds of six niger (Guizotia abyssinica Cass.) varieties ('GA-10', 'ONS-8', 'IGP-72', 'N-71', 'NB-9' and 'UN-4') were treated with 0.5, 0.75 and 1% ethyl methanesulphonate. After four generations of selection, 29 mutant lines were developed and those were evaluated from 1990-92 during Kharif (July to October) and Rabi (December to March) seasons. Average plant characteristics and yield data of four high yielding mutants along with 'IGP-76' (National Check), GA-10 (Zonal Check) and 'Semiliguda Local' (Local Check) are presented

[en] Full text: At present, the industry of flower cultivation in Mexico has been demanding new varieties produced locally. There are 6,000 hectares dedicated to the cultivation of flowers for domestic use, however the export is very low. The main production area is located in Villa Guerrero, a small town near Mexico City, where 80% of the total national production is grown. In addition, approximately 10 hectares of greenhouses are dedicated to the production of flowers for export, mainly in the Peninsula de Baja California and the Altiplano Central (Central Plateau). Unfortunately, the production of flowers in Mexico has been affected by two factors: the first, stock plants must be imported from Holland, France and the United States; and the second, there are some government restrictions on their import. Due to these factors, producers are behind in recent innovations related to new varieties. An alternative to solve this problem would be meristem in vitro culture. Plantlets from two varieties 'Polaris Yellow' pompom type and 'Dramatic' margarita type, were obtained through the meristems tip culture in the MS culture medium, to which kinetin 1.0 mg/l and NAA 0.05 mg/l were added. In preliminary studies, the plant material was irradiated with doses between 10 to 60 Gy and it was possible to determine that doses higher than 35 Gy were lethal for both varieties. In this experiment, plantlets were irradiated with seven doses (7.5, 10, 15, 17.5, 20, 22.5 Gy) of ⁶⁰Co gamma rays. They were then subcultured using three types of explants: bud, leaf and internode. The best variety for production of direct organogenesis was Polaris Yellow in a range of doses between 7.5 and 15 Gy, the buds being the best explant, while the internordes and leaves were not so suitable. In contrary, the leaf was considered to be the best explant for the induction of indirect organogenesis in the variety Dramatic, in a range of doses between 10 and 20 Gy. It was possible to obtain some mutants for color, size and shape of flowers from these materials and it is expected that in the near future they will rise to new varieties. (author)

[en] Tungro is the most serious virus disease of rice in South and Southeast Asia. It is a composite disease of two kinds of viruses, rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). Damage to the plant is mostly caused by RTBV, while RTSV acts to facilitate RTBV acquisition and transmission by insect vector. Both viruses are transmitted mainly by green leafhopper (GLH). Resistance to GLH is common in rice germplasm but extremely rare for the two viruses. To induce mutations for tungro resistance, a susceptible variety IR22 was treated with N-methyl-N-nitrosourea (MNH) following the procedure of Satoh and Omura. The panicles of rice variety 'IR22' were soaked in 1 mM MNH solution for 45 minutes at 16 to 18 hours after flowering. Two thousand six hundred and forty fertile M₁ plants were produced. From these plants M₂ lines with 10 or more seedlings were planted in the field to evaluate their reaction against tungro under natural conditions in the 1990 dry season on the IRRI central research farm, Los Banos, the Philippines. Of these, 124 M₂ lines were selected by visual evaluation. Five plants were harvested individually from each selected line. A bulk was also made from all the remaining plants in the line. In the M₃ generation, each family consisted of five sister lines and one bulked line. One line (M₃-723) showed no tungro symptoms and its related bulk segregated for resistance but all other M₃ lines from the same family were susceptible to tungro. The resistant line, M₃-723, showed low infection with RTBV and RTSV when leaves were tested by enzyme-linked immunosorbent assay (ELISA) to diagnose tungro infection. All M₄ lines from M₃-723 showed uniform resistance in the field. They were not infected with RTBV and were resistant to RTSV infection

[en] In vitro grown shoot cultures of two Indian potato varieties 'Kufri jyoti' and 'Kufri Chandramukhi' were subjected to gamma irradiation at 20 and 40 Gy. The irradiated shoot cultures were subcultured to yield a generation of plantlets. After 4-6 weeks of incubation, these shoots were transferred onto MS medium supplemented with benzylaminopurine, BAP (10mg/1) and sucrose (8% w/v) and incubated at 20 deg. C. The M₁V₃ plants were screened in vitro for late blight resistance by detached leaf method. The resistant plants were screened in M₁V₄ generation by artificial inoculation of sporangial inoculum on the pot sown plants. Chlorophyll persistence is a simple screening method for heat tolerance. Chlorophyll persistence of different plantlets showed that the percentage of injury was less in the case of plants, which had been obtained from irradiated material. In the case of control plants, there was one hundred-percent damage to the plants. The mutation frequency was calculated for characters like late blight resistance and heat tolerance (in vitro microtuberisation and chlorophyll persistence). The gamma ray dose of 40 Gy was observed to produce a higher mutation frequency

[en] The ultimate goal of crop breeding is to develop varieties with a high yield potential and desirable agronomic characteristics. In Egypt, the most important qualities sought by breeders have been high yield potential, resistance to major diseases and insects, and improved grain and eating quality. However, breeding efforts should concentrate on varieties with the potential to minimize yield losses under unfavorable conditions such as drought, and to maximize yields when conditions are favorable. Rice (Oryza sativa L.) in Egypt is completely irrigated and a significant portion of the rice cultivated area is subject to water deficit resulting from an inadequate or insufficient irrigation supply. Drought tolerance is a complex trait in that it results from the interaction of histological and physiological characters of plant with environmental factors, both above-ground and under-ground. Accordingly, root characters are closely related to drought tolerance. Little attention has been paid in Egyptian breeding programs to root characters and their relation to shoot characters. Furthermore, induced mutations are considered as one of the most important methods to induce useful mutants, especially with improved root characters, to overcome the drought problem. The present investigation aimed to study the effect of different doses of gamma rays on several characters of three Egyptian rice varieties, i.e. 'Giza 171', 'Giza 175' and 'Giza 176' and to induce one or more mutants possessing drought tolerance

[en] In pulses especially in chickpea (Cicer arietinum L.), genetic variability has been exhausted due to natural selection and hence conventional breeding methods are not very fruitful. Mutation techniques are the best methods to enlarge the genetically conditioned variability of a species within a short time and have played a significant role in the development of many crop varieties. Investigations on the effects of ionizing radiations and chemical mutagens in induction of macro-mutations have received much attention owing to their utmost importance in plant breeding. The present study reports a bold seeded mutant in chickpea, the most dominating pulse crop on the Indian subcontinent. Fresh seeds of chickpea variety 'Pusa-212' were procured from IARI, New Delhi and treated with different doses/concentrations of gamma rays (⁶⁰Co source at NBRI, Lucknow) and ethyl methanesulphonate (EMS), individually as well as in combination, to raise the M1 generation. Seeds of M₁ plants were sown to raise M2 plant progenies. A bold seeded mutant was isolated from 400 Gy gamma ray treatments. The mutant was confirmed as true bred, all the mutant seeds gave rise to morphologically similar plants in M₃, which were quite distinct from the control. The bold seeded mutant showed 'gigas' characteristics and vigorous growth. The plant remained initially straight but later on attained a trailing habit due to heavy secondary branching. The leaves, petioles, flowers, pods and seeds were almost double that of the parent variety, in size. The flowering occurred 10 days later than the parent and maturity was also delayed accordingly. Observations were recorded on various quantitative traits. Plant height and number of primary branches showed a significant improvement over the parent. It is interesting to note that the number of pods and number of seeds per pod significantly decreased. However, the hundred seed weight (31.73±0.59g) in the mutant plants was more than double in the parent variety (12.64±0.14g). This ultimately resulted in an increase in the overall yield of the mutant plant (38.86±1.69g) as compared to Pusa-212 (30.05±0.59g). Gamma ray induced bold seeded mutants have been reported earlier by different workers. The decrease in the number of seeds per pod and pods/plant and increase in seed weight is evidence of the fact that each trait is affected independently by the mutagenic treatment. Although the mutant was morphologically distinct, cytologically it was normal. There were 8 perfect bivalents at metaphase and the anaphase segregation was normal. It is concluded that bold seeded mutant may be utilized in various breeding programs as a donor parent for boldness character of the mutant. On the other hand the mutant may also itself be improved through crosses with other parents to accommodate more seeds in its large sized pod, which remained almost 50% empty

[en] Castor (Ricinus communis L.) is an important oilseed crop in India. To create variability mutations were induced in two cultivars 'TMV5' (maturing in 130-140 days) and 'CO1' (perennial type). Gamma rays and diethyl sulphate and ethidium bromide were used for seed treatment. Ten doses, from 100 to 1000 Gy were employed. For chemical mutagenesis five concentrations of mutagenes from 10 to 50 mM were tried. No economic mutants could be isolated after treatment with the chemical mutagens. The following economic mutants were identified in the dose 300 Gy of gamma rays. Annual types from perennial CO 1 castor CO 1 is a perennial variety (8-10 years) with bold seeds (100 seed weight 90 g) and high oil content (57%). Twenty-one lines were isolated with annual types (160-180 days) with high yield potential as well as bold seeds and high oil content. These mutants, identified in M₃ generation were bred true in subsequent generations up to M₈ generation. Critical evaluation of the mutants in yield evaluation trials is in progress

[en] Brassica oilseeds are the second most important source of vegetable oil in Pakistan. Due to the low priority attached to these to these crops in the past, no systematic breeding work was undertaken to develop improved varieties of rapeseed/mustard, resulting in a narrow genetic base of these crops. At the Nuclear Institute for Food and Agriculture (NIFA), gamma radiation was used to induce genetic variability in traits of economic importance thus diversifying the genetic base of indigenous/exotic cultivars of Brassica oilseeds