Field evaluation of mixed-seedlings with rice to alleviate flood stress for semi-arid cereals

Flash floods, erratically striking semi-arid regions, often cause field flooding and soil anoxia, resulting in crop losses on food staples, typically pearl millet (Pennisetum glaucum L.) and sorghum (Sorghum bicolor (L.) Moench). Recent glasshouse studies have indicated that rice (Oryza spp.) can enhance flood stress tolerance of co-growing dryland cereals by modifying their rhizosphere microenvironments via the oxygen released from its roots into the aqueous rhizosphere. We tested whether this phenomenon would be expressed under field flood conditions. The effects of mix-planting of pearl millet and sorghum with rice on their survival, growth and grain yields were evaluated under controlled field flooding in semi-arid Namibia during 2014/2015–2015/2016. Single-stand and mixed plant treatments were subjected to 11–22 day flood stress at the vegetative growth stage. Mixed planting increased plant survival rates in both pearl millet and sorghum. Grain yields of pearl millet and sorghum were reduced by flooding, in both the single-stand and mixed plant treatments, relative to the non-flooded upland yields, but the reduction was lower in the mixed plant treatments. In contrast, flooding increased rice yields. Both pearl millet–rice and sorghum–rice mixtures demonstrated higher land equivalent ratios, indicating a mixed planting advantage under flood conditions. These results indicate that mix-planting pearl millet and sorghum with rice could alleviate flood stress on dryland cereals. The results also suggest that with this cropping technique, rice could compensate for the dryland cereal yield losses due to field flooding.     

Growth and Yields of Intercropped Sorghum and Sunflower (Helianthus annuus L.) in Semi-arid Nigeria

Effect of five planting patterns on the growth, yield and yield components of intercropped sunflower and sorghum was studied during 1989–90 planting seasons at University of Maiduguri, Nigeria. Generally, intercropping depressed the performance of sorghum more than sunflower. Sorghum plants grown in alternate hills with sunflower had the shortest stems, the least dry matter and total seed yields per hectare, while the highest dry matter and seed yields were obtained from sorghum planted in five alternating rows with sunflower. Similarly, in sunflower, plants grown in five alternating rows with sorghum had the highest yields compared with other planting patterns, but there were no significant differences in the dry matter and total seed yields of sorghum and sunflower intercropped in three and five alternating rows. Light transmission, leaf area index and yields of both crops followed similar trends under the various planting patterns. Interplanting in five alternating rows that allowed the highest leaf area also allowed the lowest light transmission and produced the highest yields. Land use efficiency was highly improved under three and five rows interplanting by 52 and 74 % respectively.     

Agronomic Performance of Sorghum and Groundnut Cultivars in Sole and Intercrop Cultivation under Semiarid Conditions

The performance of sorghum and groundnut cultivars was studied in sole cropping and intercropping systems at Babile in the semiarid area of eastern Ethiopia in 1996, 1997 and 1999. On average, late-maturing cultivars of groundnut and sorghum gave higher dry pod yield and grain yield, respectively, when intercropped with early-maturing cultivars of the associated crops. The significant variation among groundnut cultivars in yield and yield components under intercropping with sorghum cultivars revealed that sole cropping may not provide the appropriate environment for selecting varieties intended for use in intercropping. The productivity of intercropped groundnut and sorghum cultivars, as determined by total land equivalent ratios (LER), was higher than sole cropping, indicating the presence of temporal complementarity in the use of growth resources. A mean yield advantage of 32 % was obtained under intercropping.     

Crop Rotation to Improve Agricultural Production in Sub-Saharan Africa

A three years' trial was conducted in a farmers' field in northern Ghana to evaluate the effect of sole crops (cotton, cowpea, groundnut, soybean, and sunflower) planted once or twice on yield of the staple foods of the region, maize and sorghum. Sole cropping for only one year already resulted in significant yield increases for maize and partly for sorghum compared to the conventional cropping of mixed stands of maize–sorghum or maize–groundnut and natural fallow. Lowest yield of maize and sorghum was obtained where these cereals followed maize–sorghum (monoculture). Intercropping of maize with groundnut led to subsequent maize and sorghum yields which were similar to those obtained after maize–sorghum. After growing legumes and sunflower for one year the grain and straw yield of maize and sorghum was significantly higher in the two consecutive years than after cereal (maize–sorghum) monoculture. In this trial maize and sorghum were found to be not as tolerant to the disadvantages of monoculture or preceding cereals–legumes mixture. The results suggest that continuous intercropping with cereals under the given conditions has negative effects on soil fertility and can lead to an increase in soil-borne pests and troublesome weeds like Striga comparable to monocropped cereals.     

Effects of Tillage and Cropping Systems on Soil Moisture Balance and Pearl Millet Yield

A 2-year study was conducted to determine the effects of tillage and cropping systems on soil moisture balance, growth and yield of pearl millet (Pennisetum glaucum (L.) R.Br.). Three tillage treatments, viz. minimum tillage (one harrowing), conventional tillage (two harrowing, cross) and deep tillage (ploughing followed by two har-rowings), and four cropping systems, viz. monoculture of pearl millet, pearl miliet-clusterbean (Cyamopsis tetra-gonoloba (L.) Taub.) rotation, monoculture of pearl millet with 5 t ha⁻¹ farm yard manure (FYM), and intercropping of pearl millet and clusterbean, were compared. Deep tillage improved the soil moisture storage, water use efficiency and grain yield of pearl millet while consumptive use of water was higher with minimum tillage. Total dry matter yield with deep tillage and conventional tillage was 23.2 and 10.2% higher than minimum tillage in the season 1, and the corresponding values for season 2 were 30.7 and 13.3%. The Pearl millct-clusterbean rotation and monoculture of pearl millet with the application of 5 t ha⁻¹ FYM gave 17.2 and 6.1% higher yield than monoculture of pearl millet, respectively. Maximum water use efficiency was observed in rotation followed by FYM application.     

The Effect of Intercropping Lablab purpureus L. with Sorghum on Yield and Chemical Composition of Fodder

In two years the growth and composition of mixtures of sorghum with Lablab purpureus as strips, paired rows and alternate rows were compared with those of sorghum and lablab monocrops. In the first year, when sowing did not occur until 7 August, the sorghum yields were low in the monocrop and even less in the mixed crops. Lablab yield was also reduced in mixtures compared with the monocrop, but total forage yield was greater for the mixed crops compared with sorghum alone. Of the mixed cropping systems, a reduction in the yield of lablab plants and in the phosphorus and potassium content of shed lablab leaves in paired rows suggested that there was more competition for nutrients between lablab plants grown in this treatment. In the second year, earlier sowing increased sorghum growth at the expense of lablab yield in the mixed cropping systems, with the result that total forage yield was not increased when sorghum was intercropped with lablab. However, the crude protein content of sorghum stems and leaf yield were increased in mixed crops, particularly in paired and alternate rows rather than strips, demonstrating that close configuration of the legume and cereal are necessary for the cereal to obtain most benefit from nitrogen fixed by the legume. It is concluded that, when conditions are favourable for rapid sorghum and lablab growth, the sorghum will benefit more when it is grown in paired rows with lablab rather than in strips. However, the close spacing normally adopted for paired rows may encourage competition between lablab plants and increase the requirements for phosphorus and potassium fertilizer.     

Identifying plant architectural traits associated with yield under intercropping: Implications of genotype-cropping system interactions

Increased yields of some crops have resulted from indirect selection of plant architectural traits related to yield. This study examines the potential relationship between plant architecture and yield for a legume grown under intercropping, Field experiments were conducted in 1991 to examine the response of two cowpea (Vigna unguiculata (L.) Walp.) genotypes with contrasting plant habits to sole crop and intercrop with pearl millet (Pennisetum americanum (L.) Leeke), and to identify cowpea traits associated with yield under intercropping. The cultivur with a bush-type habit was higher-yielding in sole crop, whereas the cultivar with a spreading habit was higher-yielding in intercrop. For F₂ cowpea populations, pod number was most highly correlated with seed yield in intercrop. The number of branches and nodes, particularly in areas with increased access to light, and increased internode length were also important in intercrop. Selection for improved yield in sole crop may not necessarily lead to improved yield in intercrop, and different plant traits may be more appropriate for cultivars intended for use in inter-crop than for those intended for use in sole crop.     

The Influence of Fertilizer-based Seed Priming Treatments on Emergence and Seedling Growth of Sorghum bicolor and Pennisetum glaucum in Pot Trials under Greenhouse Conditions

The effect of priming sorghum and pearl millet seeds with fertilizers was investigated. Two experiments were conducted on M35–1 (sorghum) and ICMH 356 (pearl millet), and ICSV 745 (sorghum) and Barmer (pearl millet) seeds, respectively. Treatments included nitrogen, phosphorous and potassium-based treatments which showed that 7.5 g l⁻¹ of urea substantially enhanced the final germination percentage of seeds. The second experiment included 10 priming treatments with 7.5 g l⁻¹ urea mixed with other fertilizers. Results indicated that soaking seeds for 3 days in urea + one of several fertilizers including N, P or K-based nutrient compositions or micro elements significantly increased germination percentage and speed but did not affect seedling growth at 15 or 60 days after sowing. It is concluded that seed priming treatments with fertilizers may serve as an appropriate treatment for advancing germination of the species studied.     

Differential Competitive Ability and Growth Habit of Pearl Millet and Clusterbean Cultivars in a Mixed Cropping System in the Arid Zone of India

Dryland sustainable agriculture in the arid zone of India depends upon the choice of suitable cultivars for pure and mixed crop stands. Field experiments were conducted for two years to examine the response of two contrasting cultivars each of pearl millet (Pennisetum glaucum) and clusterbean (Cyamopsis tetragonoloba) in pure stands and in mixed pearl millet‐clusterbean stands. The differential response of cultivars of both crops to pure and mixed stands resulted in a significant genotype × cropping system interaction. Reduction in seed yield of both clusterbean cultivars was greater in mixed stands with tall and long duration pearl millet MH 179 than with medium statured and early maturing HHB 67. The degree of reduction was greater in Naveen, the branched clusterbean cultivar, than in RGC 197, the single stemmed cultivar. Mixing of pearl millet HHB 67 with medium duration clusterbean cultivar Naveen produced maximum pearl millet equivalent total yield. Higher land equivalent ratios (LERs) were also observed when clusterbean cultivars were mixed with early maturing and short statured pearl millet HHB 67.     

玉米–大豆带状套作行距配置对作物生物量、根系形态及产量的影响

空间配置是影响间作套种作物生长和产量构成的关键因素之一。本研究固定玉米–大豆套作带宽200 cm,玉米采用宽窄行种植,设置4个玉米窄行行距为20 cm(A1)、40 cm(A2)、60 cm(A3)和80 cm(A4)套作处理,2个玉米和大豆净作对照处理,研究行距配置对套作系统中玉米和大豆生物量、根系及产量的影响。结果表明,套作大豆冠层光合有效辐射和红光/远红光比值均低于净作,且随着玉米窄行的增加而降低。套作系统中大豆地上地下生物量、总根长、根表面积和根体积从第三节龄期(V3)到盛花期(R2)逐渐增加,但随着玉米窄行的增加而降低。套作玉米地上地下生物量从抽雄期到成熟期逐渐增加,根体积却逐渐降低,但这些参数随玉米窄行的变宽而增加。玉米和大豆在带状套作系统中产量均低于净作,且随玉米窄行的变宽,玉米产量逐渐增加,2012和2013两年最大值平均为6181 kg hm–2,而大豆产量逐渐降低,两年最大值平均为1434 kg hm–2,产量变化与有效株数和粒数变化密切相关。此外,玉米–大豆带状套作群体土地当量比(LER)大于1.3,最大值出现在A2处理,分别为1.59(2012年)和1.61(2013年),且最大经济收益也出现在A2处理(2年每公顷平均收益为1.93万元)。因此,合理的行距配置对玉米–大豆带状套作系统中作物的生长、产量构成和群体效益具有重要的作用。     

Combined impacts of climate and nutrient fertilization on yields of pearl millet in Niger

Effects of climate variability and change on yields of pearl millet have frequently been evaluated but yield responses to combined changes in crop management and climate are not well understood. The objectives of this study were to determine the combined effects of nutrient fertilization management and climatic variability on yield of pearl millet in the Republic of Niger. Considered fertilization treatments refer to (i) no fertilization and the use of (ii) crop residues, (iii) mineral fertilizer and (iv) a combination of both. A crop simulation model (DSSAT 4.5) was evaluated by using data from field experiments reported in the literature and applied to estimate pearl millet yields for two historical periods and under projected climate change. Combination of crop residues and mineral fertilizer resulted in higher pearl millet yields compared to sole application of crop residues or fertilizer. Pearl millet yields showed a strong response to mean temperature under all fertilization practices except the combined treatment in which yields showed higher correlation to precipitation. The crop model reproduced reported yields well including the detected sensitivity of crop yields to mean temperature, but underestimated the response of yields to precipitation for the treatments in which crop residues were applied. The crop model simulated yield declines due to projected climate change by −11 to −62% depending on the scenario and time period. Future crop yields in the combined crop residues + fertilizer treatment were still larger than crop yields in the control treatment with baseline climate, underlining the importance of crop management for climate change adaptation. We conclude that nutrient fertilization and other crop yield limiting factors need to be considered when analyzing and assessing the impact of climate variability and change on crop yields.     

Effects of Population on Physiological Growth Parameters of Pigeonpea Genotypes in Sole and Intercropped Stand with Sorghum CO 22

A field experiment was conducted during khariff 1984 in sandy clay loam soil under irrigated condition at the Tamil Nadu Agricultural University, Coimbatore, with a view (i) to find out the possibility of introducing short duration dwarf variety of sorghum CO 22 as an intercrop with pigeonpea genotypes, (ii) to study the effect of different plant population levels and intercropping of sorghum CO 22 on pigeonpea genotypes, and (iii) to find out compatible pigeonpea genotypes and plant population level for pigeonpea based intercropping system with sorghum CO 22.
It was observed that increased plant density significantly increased the dry matter production, leaf area index (LAI) and crop growth rate (CGR) during early stages and reduced the net assimilation rate (NAR), relative growth rate (RGR) and CCR during later part of the growth. Intercropping of sorghum CO 22 significantly reduced the dry matter production LAI, CGR, NAR and RGR. Plants in the intercropped stands recorded higher CGR, NAR and RGR during later part of the growth. Among pigeonpea genotypes CO 5 was much affected due to intercropping with sorghum CO 22.     

Effects of Nitrogen on Dry Matter Accumulation and Productivity of Three Cropping Systems and Residual Effects on Wheat in Deep Vertisols of Central India

A field experiment was conducted on deep vertisols of Bhopal, India to study the effects of three levels of nitrogen (N), namely 0, 75 and 100 % of the recommended dose of nitrogen (RDN), on the dry matter accumulation (DMA) and productivity of three cropping systems (sole soybean, sole sorghum and soybean + sorghum intercropping) during the rainy season and their residual effect on the subsequent wheat crop during the post-rainy season. During the rainy season, sole sorghum was found to have significantly higher DMA and productivity in terms of soybean equivalent yield (SEY) than sole soybean or soybean + sorghum intercropping. Increasing the N dose from 0 to 100 % RDN significantly improved the DMA and SEY. At a low fertility level (N₀), soybean + sorghum intercropping was found to be more productive, while at a high fertility level (100 % RDN), sole sorghum was more productive than the other two cropping systems. However, during the post-rainy season, sole soybean as the preceding crop gave the highest DMA and seed yield of wheat, which were similar to those found with soybean + sorghum intercropping. Sorghum followed by wheat gave the lowest DMA and seed yield of wheat. Application of 100 % RDN irrespective of cropping system during the preceding crop improved the DMA of wheat but not its seed yield. However, N applied to the wheat crop significantly increased its DMA and seed yield.     

Sorghum grain yield,forage biomass production and revenue as affected by intercropping time

Sorghum is an excellent alternative to other grains in poor soil where corn does not develop very well, as well as in regions with warm and dry winters. Intercropping sorghum [Sorghum bicolor (L.) Moench] with forage crops, such as palisade grass [Brachiaria brizantha (Hochst. ex A. Rich) Stapf] or guinea grass (Panicum maximum Jacq.), provides large amounts of biomass for use as straw in no-tillage systems or as pasture. However, it is important to determine the appropriate time at which these forage crops have to be sown into sorghum systems to avoid reductions in both sorghum and forage production and to maximize the revenue of the cropping system. This study, conducted for three growing seasons at Botucatu in the State of São Paulo in Brazil, evaluated how nutrient concentration, yield components, sorghum grain yield, revenue, and forage crop dry matter production were affected by the timing of forage intercropping. The experimental design was a randomized complete block design. Intercropping systems were not found to cause reductions in the nutrient concentration in sorghum plants. The number of panicles per unit area of sorghum alone (133,600), intercropped sorghum and palisade grass (133,300) and intercropped sorghum and guinea grass (134,300) corresponded to sorghum grain yields of 5439, 5436 and 5566 kg ha⁻¹, respectively. However, the number of panicles per unit area of intercropped sorghum and palisade grass (144,700) and intercropped sorghum and guinea grass (145,000) with topdressing of fertilizers for the sorghum resulted in the highest sorghum grain yields (6238 and 6127 kg ha⁻¹ for intercropping with palisade grass and guinea grass, respectively). Forage production (8112, 10,972 and 13,193 Mg ha⁻¹ for the first, second and third cuts, respectively) was highest when sorghum and guinea grass were intercropped. The timing of intercropping is an important factor in sorghum grain yield and forage production. Palisade grass or guinea grass must be intercropped with sorghum with topdressing fertilization to achieve the highest sorghum grain yield, but this significantly reduces the forage production. Intercropping sorghum with guinea grass sown simultaneously yielded the highest revenue per ha (€ 1074.4), which was 2.4 times greater than the revenue achieved by sowing sorghum only.     

Effect of Drought Stress on Yield and Quality of Maize/Sunflower and Maize/Sorghum Intercrops for Biogas Production

Intercropping represents an alternative to maize (Zea mays L.) monoculture to provide substrate for agricultural biogas production. Maize was intercropped with either sunflower (Helianthus annuus L.) or forage sorghum [Sorghum bicolor (L.) Moench] to determine the effect of seasonal water supply on yield and quality of the above‐ground biomass as a fermentation substrate. The two intercrop partners were grown in alternating double rows at plant available soil water levels of 60–80 %, 40–50 % and 15–30 % under a foil tunnel during the years 2006 and 2007 at Braunschweig, Germany. Although the intercrop dry matter yields in each year increased with increasing soil moisture, the partner crops responded quite differently. While maize produced significantly greater biomass under high rather than low water supply in each year, forage sorghum exhibited a significant yield response only in 2006, and sunflower in none of the 2 years. Despite greatly different soil moisture contents, the contribution of sorghum to the intercrop dry matter yield was similar, averaging 43 % in 2006 and 40 % in 2007. Under conditions of moderate and no drought stress, sunflower had a dry matter yield proportion of roughly one‐third in both years. In the severe drought treatment, however, sunflower contributed 37 % in 2006 and 54 % in 2007 to the total intercrop dry matter yield. The comparatively good performance of sunflower under conditions of low water supply is attributable to a fast early growth, which allows this crop to exploit the residual winter soil moisture. While the calculated methane‐producing potential of the maize/sorghum intercrop was not affected by the level of water supply, the maize/sunflower intercrop in 2006 had a higher theoretically attainable specific methane yield under low and medium than under high water supply. Nevertheless, the effect of water regime on substrate composition within the intercrops was small in comparison with the large differences between the intercrops.     

Inter-cropping and Border-cropping of Compatible Crops in Finger Millet (Eleusine coracana Gaertn.) under Garden Land Conditions

With a view to explore the possibility of developing the most economic and viable intercropping and border-cropping systems with nitrogen management in finger millet, an experiment was conducted at Tamil Nadu Agricultural University, Coimbatore, India during summer season (December—March) under garden land condition. Different inter-crops tested were sorghum, sunflower, lady's finger, onion and cluster beans. The study indicated that intercropping and border-cropping in direct sown finger millet under irrigated condition were possible. The best and most remunerative border-crop as well as inter-crop in finger millet was onion. Application of 90 kg N/ha would be sufficient for such a cropping system in a sandy clay loam soil of medium fertility. Onion and cluster beans exhibited companion effect and sunflower and sorghum exerted competitive effect on growth and production of finger millet.     

有机高粱与不同作物间作对群体产量及效益的影响

为了明确有机高粱与不同作物间作对群体产量及效应的影响,以有机高粱指定品种“红缨子”和本地花生、大豆、向日葵、白云豆、眉毛豆、四季豆、米豆、绿豆、红苕为试验材料,比较分析了有机高粱和不同作物间作对群体产量和效益的影响。结果表明,无藤豆类作物四季豆、眉毛豆、白芸豆可作为有机高粱间作的首选作物。     

双季糯高粱间作大豆田间配置方式优化

为了减轻双季糯高粱连作障碍,优化双季糯高粱、大豆田间配置结构,提高两季作物产量效益,以常规双季糯高粱‘国窖红1 号’、‘南豆12’为试验材料,研究不同田间配置方式对糯高粱、大豆复合种植、净作模式下产量、效益的影响。结果表明：复种模式下作物总产量、总产值均高于双季糯高粱、大豆净作模式,头季糯高粱产量、千粒重、穗粒重和穗长随厢宽的增加而降低,再生季糯高粱、大豆表现为先增后减的趋势;双季糯高粱总产量最高的为1.7 m开厢处理,达8352.9 kg/hm2,大豆产量最高为1.8 m开厢处理,达1888.95 kg/hm2,两作物总产值、净收益以1.7 m 开厢处理最高,分别为47293.92 kg/hm2、29976.42 kg/hm2,其次为1.8 m开厢处理,以上两处理为最优田间配置方式。产投比以净作双季糯高粱最大,净作大豆最低。     

多样性种植模式对糯高粱生长及高梁炭疽病发生的影响

旨在阐述多样性种植模式对于糯高粱农艺性状、生理特性的影响及防控高梁炭疽病的效果,为推广糯高粱栽培技术和防控高梁炭疽病进一步提供理论依据。采用糯高粱与大豆、花生间套作,同时应用隔年换带轮作技术,结果表明：与单作糯高梁比,多样性种植模式对糯高梁的穗长、千粒重、穗粒重等农艺性状有一定影响;多样性种植模式对糯高粱开花期的净光合速率、蒸腾速率、气孔导度、胞间CO2浓度等光合特性有显著性影响;多样性种植模式对高梁炭疽病发病株率、病情严重度分级、病情指数有显著性影响;对高粱炭疽病的防控,A2B2种植模式相对防控效果最好,高达71.95%。糯高梁与大豆、花生间套作的多样性种植模式对糯高粱生长有影响,能够提高糯高粱光合能力,有效控制高梁炭疽病的发生,对大面积生产具有较大的利用价值。     

Recurrent Selection for Increased Grain Yield and Resistance to Downy Mildew in Pearl Millet*

Six pearl millet (Pennisetum glaucum [L.] R. Br.) composites were subjected to three or more cycles of selection in multilocational yield trials and downy mildew disease nurseries in India. The base and selected populations were tested (a) over four years at three locations in India (11° to 29°N), (b) under terminal-drought and optimal moisture conditions for two years, and (c) under induced downy mildew infections to determine the impacts of selection on grain yield, agronomic traits, and resistance to downy mildew (Sclerospora graminicola Sacc. Schroet.). Mean grain yield increases for four composites undergoing three to six cycles of selection ranged between 23 to 94 kg ha^-1 cycle^-1 (0.9 to 4.9 % cycle^-1) which, averaged over composites, amounted to 3.3 % cycle^-1. Yield gains were generally expressed at all test locations and under both terminal-drought and optimal moisture environments. The gains in grain yield were associated with increases of both biomass and harvest index without extending the growth duration except in the earliest composite. Susceptibility to downy mildew remained below 10 % in all selected populations. Thus, the effectiveness of recurrent selection for increasing yield and yield stability of pearl millet is clearly demonstrated.