Enzymes of Ammonia Assimilation and Transamination in Relation to Hybrid Vigour in Pearl Millet (Pennisetum americanum L. Leeke)

Changes in the activities of enzymes of ammonia assimilation viz., glutamate dehydrogenase (GDH), glutamine synthetase (GS) and glutamate synthase (GOGAT), together with the activities of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) were analysed in the topmost fully expanded leaf of pearl millet (Pennisetum americanum L. Leeke) hybrid BJ-104 , and its parents, J-104 and 5141-A , during the entire period of growth in field. Ammonia assimilation enzymes showed strong ontogenic trends and the hybrid attained activities either equal to the better (male) parent or showed better parental heterosis. In contrast to this both GOT and GPT activities were slightly higher than the poor (female) parent. The role of these enzymes in relation to chlorophyll synthesis and transport of metabolites from cellular compartments of C₄ plants, are discussed. Surveying the literature on attempts to propose biochemical criteria for hybrid vigour, it is proposed that there cannot be a universal criterion, rather rate limiting steps in different cultivars should be searched.     

Gene Action in Pearl Millet (Pennisetum americanum L. Leeke)

Grain yield was largely governed by non-additive (SCA) type of gene action with the significant existence of additive (GCA) type of gene action. GCA variance due to females was significant whereas due to males was non-significant under all environments. SCA variance was highly susceptible to the changing environments as compared to GCA component of females, whereas GCA component of males was not at all interacting with environments. Proportion of SCA and GCA variances distorted on pooling the data and was contradictory. Such distortion of the proportion on pooling was observed due to large amount of g x e interactions. Impact of interaction of genetic variance components with environments, its proportion, utility and breeding approaches are discussed.     

Growth Analysis Using Classical and Curve-Fitting Methods in Relation to Productivity in Pearl Millet (Pennisetum americanum L. Leeke)

The factors controlling productivity (dry matter production) in a pearl millet ( Pennisetum americanum L. Leeke) hybrid BJ-104 and its inbred parents, J-104 and 5141-A , were investigated using the harvest interval and curve-fitting methods. During initial stages, the hybrid showed highest total dry weight, leaf dry weight and leaf area, than the inbred lines. However, with age these differences decreased considerably. The male parent attained total dry weight almost equal to the hybrid by d 45, whereas the female parent attained it by d59.
The derived growth parameters like RGR, LAR, LWR and SLA showed strong ontogenic decline. Further, considerable cultivar variations were also recorded. Importance of the growth parameters in determining productivity is discussed and it is emphasized that higher accumulation of dry matter during initial seedling stages may be an important factor.     

The Potential for Exploiting Variation in Salinity Tolerance in Pearl Millet (Pennisetum americanum (L.) Leeke)

Shoot and root growth and plant dry weight were determined for twenty four accessions of pearl millet, Pennisetum americanum (L.) Leeke, after two weeks growth in saline solution culture at EC 20 dS m^-1. The EC was achieved using NaCl + CaCl₂ 1:1 by weight in solution culture. Although salinity markedly inhibited growth of all accessions, three, 93613, KAT/PM-2 Kitui, and Kitui local produced significantly greater dry matter, and they and 93612 had longer shoots than the other accessions. Accessions WCA 78 and Bulk 7704 were highly sensitive to salinity in all 3 characters measured. There was considerable variation between the 24 accessions, suggesting that selection for increased tolerance to salinity in pearl millet should be possible. This was examined using normal seed of the cultivar Al/3. A first cycle of selection screened 16,000 seeds after 15 days growth in nutrient solution at EC 26 dS m^-1. 106 individuals were selected to form the S₁ selection line. Selected seedlings were grown to maturity and polycrossed. In a second cycle of selection, 30,000 S₁ polycross progeny were screened as previously, but at EC 30 dS m^-1. A selection intensity of 0.08% was achieved. The selected plants were again grown to maturity and again polycrossed. Efficiency of the selection procedure was assessed from comparison in sand culture of the performance of the selected line with the unselected Al/3 line and Kitui local which from the previous assessment of the 24 accessions was rated as relatively salinity tolerant. The selection line was superior to the other two lines at four salinity levels. The results of this study suggest that further improvement in salinity tolerance in pearl millet may be expected from further selection and breeding, using the methods described here.     

Inheritance of genetic malesterility in Pennisetum americanum (L.) Leeke

Summary A spontaneously occurring male sterile condition was located in an inbred line Vg 272 of Pennisetum americanum. Male sterility was inherited as a monogenic recessive condition and showed independent assortment with hairy leaf surface phenotype. Transfer of male sterile allele to inbreds Vg 212 and IP 482 revealed no cytoplasmic effects on the expression of male sterility. Stigmas of the male sterile plants were found to possess the same amount of receptivity upto three days with normal seed set, upto six days with reduced seed set and almost with nil receptivity on the seventh day.     

Chlorophyll Content, Hill Reaction and PEPcase Activity in Relation to Hybrid Vigour in Pearl Millet during Early Seedling Growth

Three hybrids of Pennisetum americanum L. Leeke were analyzed for growth and photosynthetic components during early growth and compared with their respective parents. Growth in terms of shoot length, fresh weight and dry weight along with the chlorophylls, and Hill activity revealed better parental and/or mid parental heterosis in all the hybrids over their respective parents. However, PEPcase activity displayed heterosis only in BJ-104. In other two hybrids no heterosis over the parents could be observed indicating thereby that the activity of this enzyme may not be rate limiting in parental lines.
Nevertheless, it appears that in pearl millet hybrids improved photosynthetic apparatus as observed in chlorophyll contents and Hill reaction may be one of the early expressions of hybrid vigour.     

Genetics of induced dwarf mutants in pearl millet,Pennisetum americanum (L.)Leeke

Summary Inheritance pattern of seven dwarf mutants revealed each of them to be controlled by a single recessive gene. Tests for allelism indicated existence of two groups of dwarfs, group 1 comprising six mutants and group 2 a single dwarf. The dwarfs of group 1 were found to be allelic to D₂ of the dwarf types already known in this crop and the dwarf of group 2 was allelic to D₁ of these types.Botany Department, R.V.V.N. College, Dharanikota, India.     

Confirmation of a new source of cytoplasmic-genic male-sterility in bulrush millet (Pennisetum americanum (L.) Leeke)

Summary Results of a previous study indicated that the male-sterility discovered in a population of ex-Bornu bulrush millet, an improved selection from northern Nigeria, may represent a new source of male-sterility in the species. The present experiment was conducted to test this hypothesis.Tifton 23B₁, Tifton 239B₂ and L67B₃ which are male-sterility maintainers for the three known sources of cytoplasmic-genic male-sterility in bulrush millet viz. A₁, A₂ and A₃, respectively, were crossed with male-sterile ex-Bornu. All three maintained male-sterility in ex-Bornu but not as well as gero-B, which is the selfed progeny of an ex-Bornu plant was an excellent maintainer for ex-Bornu. Gero-B maintained male-sterility in Tifton 23A₁ and L67A₃ sources but was a partial fertility restorer for Tifton 239A₂. Tifton 186 which was reported to be a maintainer for A₁, A₂ and A₃ sources restored male-fertility in ex-Bornu. These results confirmed the view that male-sterile ex-Bornu is a new source of cytoplasmic-genic male-sterility in bulrush millet.     

Male-sterility in nigerian bulrush millets (Pennisetum americanum (L.) K. Schum)

Summary The occurrence of three male-sterile plants is reported. One in a population of ex-Bormu, an improved recommended variety of day-length neutral gero bulrush millet and the two others in the selfed progeny of a population of maiwa bulrush millet, a short-day photoperiod-sensitive type. Tests confirmed the cytoplasmic-genic nature of the male-sterility in the gero population. No tests could be conducted for maiwa.The transfer of male-sterility from the male-sterile Tift 23A bulrush millet, obtained from the United States, into a maiwa population is also reported. After six backcrosses the maiwa genotype appeared to have been reconstituted against the background of a male-sterility inducing cytoplasm. Maiwa male-sterility maintainer plants have also been identified.     

A Test of the 'Tall-Dwarf" Hypothesis in Pearl Millet, Pennisetum glaucum (L.) R. Br.

Positive height-grain yield relationships exist for many cereals, but cannot be fully used in breeding because of lodging and harvestability problems in tall cultivars. Law et al. (1978) proposed a “tall-dwarf” hypothesis for wheat, in which the positive effects of minor height genes could be exploited by selecting for them in a major dwarfing gene background. The applicability of this hypothesis to pearl millet was tested by crossing a set of dwarf S₁ progenies (from a single population) which varied in height onto two male-sterile lines. Mean (by S₁ pollinator) hybrid grain yield was closely related to mean hybrid height (r²= 0.60) over a range of mean yields of 3.0–3.9 t ha^?1 and a range of mean heights of 126–165 cm. The effect of height was expressed as an increase in grain number in one cross and as an increase in grain mass in the other, indicating the importance of background genetic effects on yield-height relationships in dwarf hybrids. The concept of “tall-dwarfs” appears to be applicable to pearl millet.     

Peroxidase Isozyme Pattern in Pearl Millet Lines Resistant and Susceptible to Downy Mildew

Peroxidase isozyme patterns of five downy mildew (DM) resistant inbred lines (PIB-57-1, PIB-1248, PIB-1356, PIB-1364 and PIB-1440), five susceptible lines (PIB-1335-1-1, PIB-1314-2-2, PIB-2231-1, 7042 and PIB-1530-1-1) and DM free plants from the susceptible lines of pearl millet were studied. The results suggested a possible involvement of an isoperoxidase (C9) in imparting the resistance. The involvement of two other isozymes (C5 and C6) was also indicated in the1 resistance mechanism. The specific differentiation m particular isozyme pattern can be a useful criterion for characterization of resistance to downy mildew.     

Behaviour of Polyphenol Oxidase, IAA Oxidase and Catalase in Germinating Rice in Relation to Salt Tolerance

Activities of the enzymes polyphenol oxidase, indole-3-acetic acid (IAA) oxidase and catalase were compared from endosperms and embryoaxes of germinating rice ( Oryza sativa ) seeds of two sets of cultivars differing in salt tolerance, raised under increasing levels of NaCl salinity. Salt sensitive cvs. Ratna and Jaya were characterized by higher polyphenol oxidase activity in embryoaxes under salinisation as compared to salt tolerant cvs. CSR-1 and CSR-3. In endosperms of salt sensitive cultivars the enzyme activity decreased under salinisation whereas in tolerants it increased due to salinity. In vitro studies using desalted enzyme extracts showed a continuous increase in polyphenol oxidase activity with increasing concentration of NaCl (0–1000 mM) in the reaction medium. IAA oxidase activity increased due to salinity in embryoaxes of both sets of cultivars, the effect was greater in sensitive cultivars than tolerants. NaCl when incorporated in the reaction medium caused decrease in IAA oxidase activity. Activity of catalase decreased with increase in salinity with greater decrease in sensitive cultivars than tolerants. Results suggest possible different behaviours of oxidative enzymes in germinating seeds of rice cultivars differing in salt tolerance and that salt tolerance ability is associated with lower polyphenol oxidase and IAA oxidase activities and higher catalase activity in embryoaxes under salinisation.     

Pearl Millet Phenology and Growth in Relation to Thermal Time under Arid Environment

Pearl millet ( Pennisetum glaucum L.R.Br.) hybrid MH 179 was grown under two moisture regimes viz., optimal moisture and rainfed conditions. The field experiment was continued for three consecutive rainy seasons to quantify the pearl millet development with thermal time. The possible influence of variation in natural sowing date on the relationships between crop development and thermal time have been described. At cardinal temperatures of 10°C (base temperature below which pearl millet development ceases), 33°C (optimal temperature for development) and 45°C (maximum temperature at and above which no development takes place), the crop required 1490–1794°Cd thermal time to reach physiological maturity. The thermal time requirement for different developmental stages was influenced by the sowing time and moisture availability during the growing season of the crop.
The leaf tip appearance on the main shoot of pearl millet in relation to thermal time was almost linear under both moisture conditions requiring about 44–50°Cd ± 2.6 °Cd leaf⁻¹, till the appearance of the flag (last) leaf. However, leaf tip appearance on primary tillers was slightly slower and required 53-58°Cd ± 4.7°Cd for each new leaf. Appearance of first primary tiller was later (at 320°Cd after emergence) under the rainfed condition as compared to the crop under the optimal moisture (at 250°Cd).Thereafter, the tiller appearance in relation to thermal time under both moisture conditions was at a linear rate of about 53-56°Cd ± 9.5°Cd tiller⁻¹.
Effect of microclimatic variations, canopy temperature, radiation and photoperiod on the phenology-thermal time relationships have been discussed under both the moisture conditions.     

Effect of Concentration of Seed Hardening Chemicals on Physiological Characters of Pearl Millet (Pennisetum typhoides Stapf and Hubb)

A laboratory study was taken up in the Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore in the year 1986 to fix optimum concentration and to evaluate the efficiency of CCC (2-chloroethyl trimethyl ammonium chloride), succinic acid and sodium chloride as seed hardening chemicals for pearl millet. The study revealed that CCC 100 ppm, succinic acid 0.15 per cent and sodium chloride 1 per cent concentrations were better in improving the germination per cent, root : shoot ratio and vigour index of pearl millet.     

Peroxidase Activity in Relation to Plant Height and Seed Yield in Indian Mustard (Brassica juncea L. Coss)

Peroxidase levels were assayed in 12 genotypes and in 36 F₁cross progenies of Indian mustard ( Brassica juncea L. Coss) at twelve stages of development, starting from seed germination till seed formation. The levels of peroxidase activity and the coefficient of variation emphasized the role of differential enzyme activity at different stages of development. Genotypes were also evaluated for plant height and seed yield. The correlations of peroxidase activity in 24 h soaked seeds with plant height and seed yield were significantly positive while those of enzyme activity in 45 days old plants with these traits were significantly negative. The study suggests the changing role of enzyme at two critical stages of plant development.     

Morphology,cytology and forage potential of Pennisetum americanum (L.) K. Schum. x P. Purpureum Schum. amphidiploids

Summary F₁ hybrids between short-day photoperiod- sensitive maiwa bulrush millet, Pennisetum americanum (2n=14), and elephant grass, P. purpureum (2n=28), are triploid (2n=21), sterile, and can only be propagated vegetatively. Fertile amphidiploids, (2n=42, with 21 bivalents) were produced by colchicine treatment. Good seed set was obtained upon selfing the amphidiploids and the progeny exhibited variable pollen fertility and bivalent univalent and multivalent formation.Reciprocal crosses between elephant grass and the colchicine-induced amphidiploid failed to produce seeds. The maiwa millet x amphidiploid cross resulted in poor seed set and the reciprocal failed. Maiwa x amphidiploid hybrids were pollen sterile with 2n=21, rather than the expected 2n=28, indicating chromosome elimination.Morphologically, the amphidiploids and maiwa x amphidiploid hybrids closely resembled elephant grass and the F₁ hybrid. The amphidiploids showed no superiority over the F₁ hybrid and elephant grass in either forage yield or quality but one maiwa x amphidiploid genotype surpassed a promising local elephant grass selection in forage dry matter yield and flowered for a relatively short period.     

Seed Number and 100‐Seed Weight of Pearl Millet (Pennisetum glaucum L.) Respond Differently to Low Soil Moisture in Genotypes Contrasting for Drought Tolerance

Water stress after flowering, one of the major factors limiting yields of pearl millet, affects both seed setting and grain filling and is a consequence of more/less water used prior to anthesis. However, whether genotypes have different sensitivities for seed setting and filling under drought, if exposed to similar stress intensity, is unclear. Experiments were conducted in two pairs of pearl millet genotypes, that is, PRLT2/89‐33 and H77/833‐2, 863B and 841B, contrasting for terminal drought tolerance, and two genotypes, ICMR 01046 and ICMR 01029 (IL‐QTLs), introgressed with a terminal drought tolerance QTL from PRLT2/89‐33 into H77/833‐2. Total seed weight, panicle number, 100‐seed weight, seed number and stover biomass were measured at different soil moistures and throughout grain filling. Sensitive H77/833‐2 had higher seed number and yield under well‐watered (WW) conditions than in PRLT2/89‐33 and IL‐QTLs. Upon increases in water stress intensity, H77/833‐2 suffered losses mostly in stover biomass (45 %) and seed number (60 %) at 0.3 FTSW whereas the biomass and seed number of PRLT2/89‐33 decreased little (20 % and 25 %). The 100‐seed weight of H77/833‐2 decreased only 20 % under stress. Tolerant 863B also maintained a higher seed number and biomass under water stress than 841B. Grain filling duration in PRLT2/89‐33 and IL‐QTLs was similar to that of H77/833‐2 under WW conditions but lasted longer than in H77833‐2 under water stress (WS). Similarly, seed growth of 863B was longer than 841B under WS. It is concluded that the higher seed yield of tolerant parents PRLT2/89‐33 and 863B, and of IL‐QTLs under WS was explained by the retention of a higher number of seeds than in sensitive lines, while the decrease in the 100‐seed weight was proportionally less than the decrease in seed number. Phenotype with lesser number and larger size of panicles and larger grain size, like genotypes PRLT2/89‐33 and 863B, withstood post‐anthesis water stress better. IL‐QTL inherited part of these characteristics, indicating a role for the terminal drought QTL in maintaining larger seed number and higher 100‐seed weight. The continuous stover biomass increase under WW in H77/833‐2, due to tillering, might indicate that tiller growth and grains are in competition for resources after anthesis, and this may relate to the relatively shorter grain‐filling period.     

甘蓝型油菜杂种优势和过氧化物酶的关系分析

对3个甘蓝型油菜杂交组合和亲本的农艺性状表现及其与过氧化物酶活性的关系进行了浅析,研究结果表明：杂种的产量性状,如单株粒重、单株有效角果数、有效分枝数、主花序有效角果数等,比其双亲有明显的优势;杂种花期的过氧化物酶活性高于双亲,与株高、有效分枝数、有效角果数、千粒重等性状具有显著的相关性;杂种的过氧化物酶同工酶谱表现为双亲的互补型。     

糜子胚发育的过程及其时间进程

通过常规石蜡切片染色观察，详细研究了糜子胚发育的过程及其时间进程。糜子胚发育的全程包括3个阶段。1.原胚阶段：开花后8-10小时，合子横分裂形成2-细胞胚，再经过一系列有序的细胞分裂，在开花后1天时发育为棒状胚；开花后2天时梨形和弯曲形胚，3天时为蝌蚪形胚。2.器官分化阶段：始于蝌蚪形胚近胎座的一侧细胞液泡化，各     

用A-PAGE鉴定谷子遗传多样性

蛋白质是结构基因编码的产物 ,其组成不因环境条件的改变而改变 ,可以作为对其编码的结构基因的标记。大量研究表明 ,禾谷类作物种子贮藏蛋白具有相当大的多态性 ,不同品种贮藏蛋白的电泳谱带存在较大差异 ,因此提供了一种表征基因型差异的有效而简便的方法[1～ 3] 。谷子种子的主要贮藏蛋白是醇溶蛋白 ,占种子总蛋白的4 5 %～ 6 0 % [4 ] 。在研究材料很少的情况下 ,碱性检测条件下谷子醇溶蛋白十二烷基磺酸钠 聚丙烯酰胺凝胶电泳 (SDS PAGE)检测出的遗传差异很小或几乎没有[5,6 ] 。近年来 ,禾谷类作物种子醇溶蛋白以酸性聚丙烯酰胺凝…