and yield of pearl millet (Pennisetum glaucum (L.) R. Br.) grown in Sahelian conditions
01 Jan 1997-
TL;DR: In this article, the authors assessed the impact of water deficits at three develop- ment stages: prior to flowering, at the beginning of flowering, and at the end of flowering in pearl millet grown in experimental conditions similar to Sahelian farming conditions.
Abstract: l~lH~~~~il~~~~~l Abstract Several studies conducted under high input conditions have indicated little susceptibility of pearl millet to water deficit until1 early grain filling, because the Introduction losses in main shoot production were fully compens- ated by increased tiller fertility. The present study assessed the impact of water deficits at three develop- ment stages: prior to flowering (S30), at the beginning of flowering (545), and at the end of flowering (S60) in pearl millet grown in experimental conditions similar to Sahelian farming conditions. It included a control irrigation treatment simulating the natural distribution of rainfall throughout the cropping season. Both bio- mass production and grain yield were severely reduced by S30 and S45, while S60 had no effect. In S30 and S45, the flowering of tillers was delayed or totally inhibited. In both of these treatments, the low number of productive tillers did not compensate for damage The usual effects of drought on the development of a plant are a lowered production of biomass and/or a change in the distribution of this biomass among the different organs. The drought resistance of a cultivated plant reflects its capacity to limit the impact on the economic yield of these changes in biomass production and distribution. This capacity will depend on the devel- opment phase affected by water deficit, as well as on the intensity and the length of the drought. In Sahelian climates, where agrosystems are based essentially on pearl millet (Petznisetum gluucum (L.) R. Br.), the risks of drought can be classed into two types according to their impact on pearl millet cultivation. l i to panicle initiation and flowering of the main shoot. (1) Droughts at the beginning or end of the cropping All treatments maintained green leaves on the main season, frequent and often long, but to which peasant shoot during the grain filling period, and in S30 leaf farmers respond by successive re-sowing (in the case growth recovered from mid-season drought. These of early droughts) or by the choice of short-season results illustrate how pearl millet mostly escapes cultivars tolerant of post-floral water deficits (in the drought by matching its phenology to the mean rainfall case of late droughts); distribution in the Sahel. In the case of mid-season (2) Intermediate droughts, less frequent and often brief drought, some late productive tillers and the mainten- (about 10 d), but very unpredictable and without any ance of green leaf biomass of the main shoots limited, practical remedies. They affect development stages but did not overcome, the yield losses. This study such as initiation of panicles, earing, or flowering stresses the importance of agro-ecological conditions which, in cereals, are generally sensitive to water in control treatments, particularly the water regime deficits. The variability of these droughts in time and and crop density, when assessing crop drought space complicates the characterization of drought- __ .-- - resistant varieties. I l resistance.
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TL;DR: The results achieved so far indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress.
Abstract: As the result of intensive research and breeding efforts over the last 20 years, the yield potential and yield quality of cereals have been greatly improved. Nowadays, yield safety has gained more importance because of the forecasted climatic changes. Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. Yield safety can only be improved if future breeding attempts will be based on the valuable new knowledge acquired on the processes determining plant development and its responses to stress. Plant stress responses are very complex. Interactions between plant structure, function and the environment need to be investigated at various phases of plant development at the organismal, cellular as well as molecular levels in order to obtain a full picture. The results achieved so far in this field indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress. Here we attempt to summarize the currently available information on cereal reproduction under drought and heat stress and to give an outlook towards potential strategies to improve yield safety in cereals.
1,547 citations
30 Jan 2019
TL;DR: The causes ofClimate change, stresses produced due to climate change, impacts on crops, modern breeding technologies, and biotechnological strategies to cope with climate change are summarized in order to develop climate resilient crops.
Abstract: Agriculture and climate change are internally correlated with each other in various aspects, as climate change is the main cause of biotic and abiotic stresses, which have adverse effects on the agriculture of a region. The land and its agriculture are being affected by climate changes in different ways, e.g., variations in annual rainfall, average temperature, heat waves, modifications in weeds, pests or microbes, global change of atmospheric CO2 or ozone level, and fluctuations in sea level. The threat of varying global climate has greatly driven the attention of scientists, as these variations are imparting negative impact on global crop production and compromising food security worldwide. According to some predicted reports, agriculture is considered the most endangered activity adversely affected by climate changes. To date, food security and ecosystem resilience are the most concerning subjects worldwide. Climate-smart agriculture is the only way to lower the negative impact of climate variations on crop adaptation, before it might affect global crop production drastically. In this review paper, we summarize the causes of climate change, stresses produced due to climate change, impacts on crops, modern breeding technologies, and biotechnological strategies to cope with climate change, in order to develop climate resilient crops. Revolutions in genetic engineering techniques can also aid in overcoming food security issues against extreme environmental conditions, by producing transgenic plants.
742 citations
TL;DR: Reproductive development of plants is highly vulnerable to water deficit, and changes in carbohydrate availability and metabolism appear to be involved in the effects of stress during meiosis and anthesis, which can cause loss of pollen fertility, failure of pollination, spikelet death, or zygotic abortion.
Abstract: Reproductive development of plants is highly vulnerable to water deficit. Stress early during this phase can delay or completely inhibit flowering, both through an inhibition of floral induction and development. The stage of meiosis is perhaps the most stress-sensitive period of reproduction in all species studied. A meiotic-stage water deficit causes pollen sterility, but usually affects female fertility only under extreme stress. Sterility occurs even though the reproductive structures of stressed plants maintain a high water status, indicating that the response is probably mediated by a sporocidal signal from elsewhere in the plant. Rice and maize plants are also highly vulnerable during flowering (anthesis) and early grain initiation. Stress during this period can cause loss of pollen fertility, failure of pollination, spikelet death, or zygotic abortion. Changes in carbohydrate availability and metabolism appear to be involved in the effects of stress during meiosis and anthesis. Stress during early grain development curtails the kernel sink potential by reducing the number of endosperm cells and amyloplasts formed. Controls underlying these effects are poorly understood, although hormones may be involved. A water deficit during any stage of grain development causes the premature cessation of grain filling. Kernel moisture content and its direct impact on metabolism appear to be key regulatory factors in shortening the duration of grain filling.
563 citations
TL;DR: This commentary identifies and characterises NUCS with agronomic potential in SSA, especially in the semi-arid areas taking into consideration inter alia: (i) what can grow under water-scarce conditions, (ii) water requirements, and (iii) water productivity.
Abstract: Modern agricultural systems that promote cultivation of a very limited number of crop species have relegated indigenous crops to the status of neglected and underutilised crop species (NUCS). The complex interactions of water scarcity associated with climate change and variability in sub-Saharan Africa (SSA), and population pressure require innovative strategies to address food insecurity and undernourishment. Current research efforts have identified NUCS as having potential to reduce food and nutrition insecurity, particularly for resource poor households in SSA. This is because of their adaptability to low input agricultural systems and nutritional composition. However, what is required to promote NUCS is scientific research including agronomy, breeding, post-harvest handling and value addition, and linking farmers to markets. Among the essential knowledge base is reliable information about water utilisation by NUCS with potential for commercialisation. This commentary identifies and characterises NUCS with agronomic potential in SSA, especially in the semi-arid areas taking into consideration inter alia: (i) what can grow under water-scarce conditions, (ii) water requirements, and (iii) water productivity. Several representative leafy vegetables, tuber crops, cereal crops and grain legumes were identified as fitting the NUCS category. Agro-biodiversity remains essential for sustainable agriculture.
301 citations
TL;DR: A multi-year on-farm field campaign over 10 villages in South-West Niger, is analysed to investigate how rainfall determines the sowing date of pearl millet and the risk of sowing failure, and the relationships between sowing dates, onset dates and observed yield and biomass at the end of the season.
145 citations
References
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TL;DR: It is suggested that, as a group, tall bread wheats would outyield dwarf wheats only under very severe drought, and the yield responses of tall and dwarf bread wheat groups obtained in these experiments agreed with those seen in extensive international trials under dryland conditions.
Abstract: With a view to understanding the basis of cultivar differences in yield under drought, a wide range of cereal cultivars representing durum wheats (Triticum turgidum L.), triticales (X Tritosecale Wittmack), barleys (Hordeum vulgare), and especially tall and dwarf bread wheats (T. aestivum L.) were studied in field experiments in north-western Mexico over three seasons. Drought was created in this rain-free environment by permanently terminating irrigation at various stages before anthesis. Control treatments were well watered throughout the growing period. Detailed measurements of plant water status, leaf area and dry matter production, anthesis date, yield components and grain yield were made. This paper presents primarily the grain yield data. Drought levels were such that the mean yield of all cultivars under drought ranged from 37 to 86% of control yield, corresponding to irrigation cut-offs varying from 69 days before mean anthesis date to only 10 days before. In each experiment the grain yield under drought showed highly significant cultivar differences, which appeared consistent between years. Yields were adjusted for drought escape by using a correction factor which ranged from 2.9 to 8.5 g/m2 per day advance in flowering, being greater in experiments with less severe drought. The demonstration of linear relationships between cultivar yield and drought intensity, as indicated by the mean yield of some or all cultivars, prompted the consideration of cultivar yield under drought as the function of yield potential (Yp, yield without drought), drought susceptibility index (S), and intensity of drought. The cultivar groups showing lowest S values (most droughtresistant) were tall bread wheats and barleys; dwarf bread wheats were intermediate, and durum wheats and triticales were the most susceptible. However, because dwarf wheats have a higher yield potential (Yp) than tall bread wheats, it is suggested that, as a group, tall bread wheats would outyield dwarf wheats only under very severe drought. Also there was considerable within-group variability of S and Yp. Cultivar S values were consistent across experiments. Yield responses of tall and dwarf bread wheat groups obtained in these experiments agreed with those seen in extensive international trials under dryland conditions.
2,031 citations
Book•
01 Jan 1993
TL;DR: Crop yields and world food supply, the domestication of crop plants, Adaptation and the ecology of yield, and the future of yield are reviewed.
Abstract: 1. Introduction 2. Crop yields and world food supply 3. The domestication of crop plants 4. Adaptation and the ecology of yield 5. Physiological aspects of crop improvement 6. Increases in yield: trends and limits 7. Inputs and the efficient use of resources 8. The future of yield.
1,014 citations
TL;DR: There has been a recent emergence in research activity on the ecology of agricultural systems as mentioned in this paper, where ecologists and agronomists have begun to combine forces to study and help solve the problems confronting our food production systems.
Abstract: There has been a recent emergence in research activity on the ecology of agricultural systems. After a long history of separation and lack of interaction, ecologists and agronomists have begun to combine forces to study and help solve the problems confronting our food production systems. Out of this the field of agroecology has begun to form. But as the field forms, considerable discussion and even controversy has surfaced as to how a research approach or methodology might best be applied to ensure the achievement of ecologically significant as well as agriculturally applicable results. It is one thing to gain an understanding of what makes an agroecosystem function, yet it is quite another to apply such knowledge to solving everyday problems faced by farmers around the world.
336 citations
TL;DR: In this paper, the authors used the specific definition of onset of rains in each year as the sowing date, the length of dry cells was calculated from the historical rainfall data, and the probability distribution of time to the next wet day and the percentage frequencies of dry spells were computed for successive days after sowing a crop.
Abstract: Recurring droughts and decreased agricultural productivity during the last two decades in West Africa point to the need for a clearer understanding of the length of dry spells, their frequencies and their probabilities. The simplest calculations of dry spells for general applications involve computation of the probabilities of maximum and conditional dry spells exceeding a user-specified threshold value from a given calendar date. For more precise applications in agriculture, it is important to consider the different periods after sowing a crop, since sowing dates in the semiarid West African regions vary from year to year. Using the specific definition of onset of rains in each year as the sowing date, the length of dry cells was calculated from the historical rainfall data. Probability distribution of time to the next wet day and the percentage frequencies of dry spells were computed for successive days after sowing (DAS) a crop. Dry-spell analysis showed a pronounced drop in the drought risk f...
167 citations