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

Pattern analysis of international sorghum multi-environment trials for grain-yield adaptation

Pattern analysis, which consists of joint and complementary use of classification and ordination techniques, was applied to grain-yield data of 12 sorghum genotypes in 25 environments to identify the grouping of genotypes and environments. The 12 genotypes represented a wide geographical origin, different genetic diversity, and three photoperiod-sensitive classes. The 25 environments represented a super population of widely different environments covering latitudes from 20°S to 45°N. The knowledge of environmental and genotype grouping helped reveal several patterns of genotype × environment (GE) interaction. The existence of two mega-environments, African and Asian, was indicated. Within these mega-environments, several subgroups were further discernible. The Asian-type subgroups of environments tended to be closer to one another, suggesting that they discriminated genotypes similarly. By contrast, the African-type sub-groups of environments were more divergent. Differential genotype adaptation patterns existed in the two mega-environments. The repeatability of the GE patterns seen in this multi-environmental trial, however, needs to be established over time

Genotypic variation in biomass production and nitrogen use efficiency in pearl millet [Pennisetum americanum (L.) Leeke]

Twenty diverse pearl millet genotypes ranging from landraces to high yielding hybrids were studied for genotypic variation in nitrogen (N) use efficiency in high (100 kg N/ha) and low fertility (20 kg N/ha) over two years in the field. The combined data over years and fertility levels indicated that despite taking up similar amounts of N, genotypes differed significantly in biomass production and thus in N use efficiency. A West African genotype, Souna B, had N use efficiency values 32% higher than the less efficient Indian genotype BJ 104 even though both genotypes had similar N uptake. An increase in N fertility decreased N use efficiency since the percentage increase in biomass was smaller than the percentage increase in N uptake

The influence of extended vegetative development and d2 dwarfing gene in increasing grain number per panicle and grain yield in pearl millet

As in other cereals, grain yield in pearl millet is directly related to grain number m−2. Hence, an attempt was made to increase grain numbers by (1) increasing the length of vegetative period (to increase potential grain number per panicle and increase leaf area and light interception before flowering) by using a non-inductive long photoperiod during the early stages of crop growth, and (2) using a dwarfing gene to vary assimilate partitioning between panicle and stem prior to flowering. Extended day length delayed panicle initiation (PI) and flowering and increased leaf area index and assimilate production. Time to flowering was directly related to assimilate allocation to individual panicles, and to grain number per panicle. Delayed PI, however, reduced panicle numbers. Dwarf hybrids partitioned more assimilates to panicles and less to stems, which was also associated with more grains per panicle. The increase in grain number per panicle was offset by decrease in panicles per plant so that neither longer vegetative stage nor dwarfing gene caused in increase in grain yield. With increase in grain numbers per panicle in the dwarfs, grain density (grains cm−2 surface area of panicle) also increased resulting in the dwarf hybrids producing smaller grains and failing to benefit from the increased grain numbers per ear

Durations of the photoperiod-sensitive and -insensitive phases of time to panicle initiation in sorghum

The development of sorghum [Sorghum bicolor (L.) Moench] is influenced by genes that control sensitivity to photoperiod, and their interaction with photoperiod and temperature. While temperature influences development throughout the life cycle of plants, photoperiod influences the vegetative stage (from seedling emergence to panicle initiation). In order to simulate plant development, it is essential to know when sorghum plants first become sensitive to photoperiod, and how long that photoperiod sensitivity persists. Ten cultivars with different levels of photoperiod sensitivity were grown in pots under natural climatic conditions both in short days (SD: 8 h day-1) and long days (LD: 17 h d-l). Plants were transferred at different times after seedling emergence from SD to LD and vice versa. The time to panicle initiation (PI) for each transfer treatment was detemfined. In cultivars that remained continuously in SD, the time to PI varied from 16 to 27 d, whereas, in continuous LD it varied from 22 to 37 d. The cultivars started reacting to photoperiod 4-9 d after seedling emergence. After sensing photoperiod stimuli, inductive effects among cultivars persisted for 4-14 d in SD, and for 15-33 d in LD depending on their intrinsic photoperiod sensitivity. The sensitivity ended 2-5 d before panicle initiation. This interval, between completion of the photoperiod-inductive phase and the actual observation of PI under the microscope, represents the time required for the photoperiod-inductive stimulus to promote sufficient cell division and growth at the shoot apex for the morphological change to become visible as a shiny globular structure, We conclude that photoperiod sensitivity in these sorghum cultivars ends shortly before or at the PI stage. Our results support the assumptions followed in several crop simulation models that sorghum remains photoperiod-sensitive until the completion of the vegetative stag

Use of grain number components as selection criteria in pearl millet.

The use of panicle number/plant and panicle surface area as indirect selection criteria for grain yield was studied in an open pollinated, synthetic dwarf variety of Pennisetum glaucum (ICMS7901) at Patancheru. Spaced plants were grown in the rainy season of 1980 and selected selfed plants were evaluated during the rainy season of 1981; further field trials were conducted in 1982 and 1984 using subsynthetics. Information on grain yield and 4 yield components (number of panicles and grains per m², number of grains per panicle and grain weight) is tabulated for the selfed progeny and subsynthetics. Data indicated that selecting for both panicle number /plant and panicle size resulted in improvements in the yield components, while selecting only for increased panicle size resulted in a notably higher grain mass

Modeling the Growth and Development of Sorghum and Pearl Millet

The 1980s have witnessed substantial increases in food production. This has raised expectations that improved systems of farming will be rapidly adopted by small farmers in developing countries. The agroecological environment of such farms is fragile and the farmers are resource-poor. Therefore, strategies recommended for increasing food production must be ecologically sound and should result in sustainable agriculture. System modeling can greatly expedite the search for improved development strategies. Recent advances in crop modeling have made it possible to simulate yields and growth of several crops under varied soil and weather conditions with different management practices. This bulletin describes the framework of CERES (Crop Estimation Through Resource and Environment Synthesis) models developed by the International Benchmark Sites Network for Agrotechnology Transfer ( IBSNAT) and The International Crops Research Institute for the Semi- Ar i d Tropics ( ICRISAT) . Recent wor k on the simulation of nitrogen transformation in soils at the International Fertilizer Development Center ( IFDC) is discussed. A section on risk analyzes the cost-benefit implications of various inputs for increased crop production. RESCAP—a resource capture model developed at ICRISAT Center is presented. This publication is a cogent source book on the current status of development of CERES and RESCAP models, their data needs, outputs, and applications

Improvement Of Drought Resistance In Pearl Millet

Pearl millet is grown almost exclusively in arid and semiarid tropical areas characterized by high growing seafon temperatures, low and frequently erratic rainfall, and shallow or sandy soils. Inadequate moisture is the major limitation to production in most of the areas. The crop appears to adapt to these conditions by a combination of short-duration important developmental periods and considerable development plasticity to maximize its use of short periods of favorable moisture. Little is known of its possible physiological adaptations to stress, although the limited information available suggests a significant heat tolerance