Grain-sorghum agronomy: optimum plant population for yield testing

Slnce the grain-grass plant type is substantially diifferent from normal sorghum grown almost everywhere, there is great need to have more information on all agronomic aspects. Bccause of their early maturity tillering habit and narrow leaves, population, density trial was conducted in order to recommend the optimum population for qrain yield testing of promising breeding materia

Biomass and harvest index as indicators of nitrogen uptake and translocation to the grain in sorghum genotypes

Nitrogen is usually the most limiting nutrient for crop production and the poor recovery of applied fertilizer nitrogen by crops is of world wide concern. The differential response of sorghum (Sorghum hivolor L. Moench) genotypes lo applied nitrogen suggests that differences in nitrogen uptake, translocation and accumulation in the grain exist1. This paper deals with (i) the extent of variation in sorghum for the above characters, (ii) correlations of these traits with agronomic traits such as days to flower, biomass and grain yield and, (iii) the implications of (i) and (ii) in breeding and crop management

Molecular characterization and assessment of genetic diversity of sorghum inbred lines

Selecting parents of diverse genetic base with contrasting phenotype is an important step in developing mapping populations for quantitative trait loci (QTL) detection and marker-assisted selection. We studied genetic diversity in 31 sorghum parents using 413 sorghum simple sequence repeats (SSR) markers. The polymorphism information content (PIC), a measure of gene diversity, varied from 0 to 0.92 with an average of 0.53 and was significantly correlated with number of alleles. The primers IS10215, IS10270 and IS10333 could differentiate all the 31 lines conclusively. Clustering analysis based on the genetic dissimilarity grouped the 31 parents into eight clusters and grouping was in good agreement with pedigree, race and geographic origin. Diverse pairs of sorghum parents were identified with contrast phenotype for various biotic and abiotic stresses with higher genetic diversity for developing recombinant inbred line (RIL) mapping populations to identify QTLs/genes for important traits in sorghum. One of the mapping populations resulted in the identification of QTLs for resistance to sorghum shoot fly and these QTL results were validated in a second mapping population.Key words: Simple sequence repeats (SSR) markers, genetic diversity, sorghum, mapping parents

Genotypic and Environmental Variation in Nodal Root Growth of Post-rainy Season (Rabi) Sorghum

Rapid initiation and growth of nodal roots (NR) are critical for the establishment of post-rainy season (rabi) sorghums grown in drying soil. The growth of NR was studied in sorghum in the field when sown at different depths in order to vary the crown depth, when different levels of irrigation water were applied to create different moisture contents in the topsoil, and in a number of cultivars to assess genotypic variability. Variation in sowing depth did not result in differences in NR growth, partly because of the capacity of sorghum to vary the mesocotyl length, which brought the crown to approximately the same depth. Different soil moisture levels in the field affected the elongation rate of NR, but not their initiation. Genotypic variation existed in the thermal time required for NR initiation and rate of elongation. The variation in NR growth was independent of the variation in shoot growth. The genotypic variability in NR growth offers an opportunity for combining root-related traits with useful agronomic character

Fitting Crop Genotypes To Abiotic Stress Environments : Problems And Prospects

Plant breeding efforts have substantially increased yields mainly of crops grown under (near) optimum conditions, especially during the last half century. This, with or without deliberate efforts, has resulted in an increase in adaptability of cullivars and stability of grain yields, even in abiotic stress environments. In order to ensure nutritional security for the growing population, especially in the tropics with its dwindling and degraded land resources, we constantly need newer crop production tzchnologies. Even in highly developed temperate agricultural systems, 60 to 80% of the seasonal variation in crop productivity is attributed to weather fluctuations (Thompson 1975; Boye 1082). In the tropics where the intensification of crop production and extension of crops to more margrnal areas are the order of the day, iticrcased research on crop productivity, especially in stress environments is callcd for

Androgenic Response of Cultured Anthers and Microspores of Sorghum

Sorghum anthers with uninucleate microspores were dissected out of spikelets and plated on MS, B5 and N6 media with kinetin, NAA and 2,4-D. The callus induction frequencies (percentage of anthers plated) for the 3 hybrids tested were 60, 20-30 and 15-20%, for CSH 9, CSH 5 and CSH 12R, respectively. Uninucleate microspores showed the most cell division, and cultures of anthers at earlier (small cells without vacuoles) or later (binucleate microspores) stages did not show any androgenic response. The highest response was obtained at 26°C. After 12 d the anthers on all media, especially B5 and N6 started to turn black. Sucrose was more effective at inducing divisions (50-60% of microspores) than maltose (15-20%). Combined treatment with NAA and 2,4-D at 2.0 mg/litre induced divisions. When NAA and 2,4-D (2 mg/litre) were combined with kinetin at 0.05, 0.1, 0.15 and 0.2 mg/litre, the response increased, with a maximum number of multicellular microspores observed at 0.2 mg/litre kinetin. Microcalli that were growing within the anthers after 20-30 d of culture were transferred to MS medium; irregular masses of calli were observed after 30 d. It is concluded that sorghum microspore cultures may be less dependent on genotype or culture conditions than are anther cultures

A perspective on drought research for enhancing field crop productivity with special reference to breeding for drought resistance

The reoent surge in literature on drought resistance in crop plants has accentuated the challenge and excitement of drought research. It is essential to note, unlike the case with most biotic stress factors, there is no nmiracle ouren for drought, neither in plants themselves nor in field management teohniques, nor i n o v e r a l l imdrovement of the agroclimate of the region (soil and water oonnarvation measures, aforestation, etc.). Rowever sufficient scope exicsts to combine all these methods to increase significantly, and stabilize crop production in many semiarid regions..

Biochemical changes during seed development in sorghum (Sorghum bicolor)

Grain dry-weight accumulation and contents of soluble sugars, starch, protein, fat and ash were investigated in developing grains of eight cultivars. In the high-lysine mutant P721 and the high-lysine Ethiopian lines IS11167 and IS11758, contents of starch were relatively low and those of protein relatively high, suggesting a possible mechanism for protein accumulation at the expense of starch accumulation. RY49, also from Ethiopia, had a comparatively high rate of protein accumulation at various phases of maturation. Fat content tended to increase for up to 28 days after flowering and the accumulation rate was highest in RY49 and IS1116

Studies on seed colouring in redgram, blackgram and bengalgram

The investigations on the effect of seed colouring of redgram, blackgram and bengalgram seeds encompassing 25 dyes were conducted to identify non-deleterious and deleterious dyes based on their effect on seed quality. The dyes namely Rhodamine-B, Fuchsine and Titan yellow for redgram, Rhodamine-B, Fuchsine and Phenol red and Rhodamine-B, Crystal violet, Titan yellow for bengalgram were found to be the best dyes for seen colouring at 0.75% concentration. In this paper we discuss developing colour standards for redgram, blackgram and bengalgram seeds and their resultant implications for Indian seed industry