Growth Of Cassava Research Articles

Dynamics of N-P-K demand and uptake in cassava

Fertilizers are required to improve productivity of cassava and meet the increasing demand for cassava as food, feed, or raw material for processing industries. Our objective was to develop nutrition indices for N, P, and K to provide quantitative insight in the dynamics of nutrient demand and uptake of cassava. On-farm experiments were conducted at six locations in Nigeria from 2016 to 2018, across the major cassava growing agro-ecologies of West Africa. Nitrogen, P, and K were applied at different rates. Uptake of nutrients was measured in leaves, stems, and storage roots at 4, 8, and 12 or 14 months after planting (MAP) and used to construct NPK dilution curves and nutrition indices. About 67, 61, and 52% of total N, P, and K were taken up at 4 MAP, with a maximum uptake rate of 0.21, 0.03, and 0.12 g/m2/d for N, P, and K, respectively. Nutrient concentrations in stems and storage roots declined gradually, in contrast to concentrations in the leaves that fluctuated within narrow ranges. Dilution curves and nutrition indices for N, P, and K were established for the first time in cassava. Dilution curves of N, P, and K in the crop for the highest NPK application treatment were described as Nc = 82DM−0.61, Pc = 7.4DM−0.54, and Kc = 43DM−0.54, when total biomass was between 5 and 57 t/ha dry matter (DM). The nutrition indices were linearly related to relative crop biomass. Insight into the nutrient uptake and dilution patterns during the growth cycle can help to understand the temporal nutrient demands of cassava and identify sustainable management practices. Initial ample supply of N and P and moderate K, with extra K top-dress during the second growth phase, will benefit cassava growth and yield. Furthermore, such information provides a basis to develop a dynamic model to simulate nutrient-limited growth of cassava.

Canopy Structure and Photosynthetic Performance of Irrigated Cassava Genotypes Growing in Different Seasons in a Tropical Savanna Climate

Growth and photosynthesis performance of cassava during early vegetative growth are important determinants of final biomass. The objective of this work was to investigate canopy structure and photosynthesis performance of four cassava genotypes (Rayong 9, Rayong 11, Kasetsart 50, and CMR38-125-77) growing under irrigation at 3 and 6 months after planting (3MAP and 6MAP). Data for the 3MAP plants were collected from cassava planted on 30 June (Rainy PD), 10 November (Cool PD1), and 15 December (Cool PD2) 2015; and for the 6MAP from those planted on 20 April 2015 (Hot PD), Rainy PD, and Cool PD1. The plants growing in the rainy season had significantly higher leaf area index (LAI) than those growing in the cool and hot seasons. Consequently, they had lower percentage light penetration at the bottom of canopy, and therefore more light interception through the canopy, and hence a higher mean net photosynthesis rate (Pn) across the six canopy levels. At the 3MAP, which is the stage of maximum rate of leaf and stem growth, the Rainy PD and Cool PD2 plants of CMR38-125-77 showed the highest LAI and highest mean Pn. Similarly, the Cool PD1 plants of Kasetsart 50 showed the highest LAI and highest mean Pn. In contrast, at 6MAP during the stage of active starch accumulation in storage roots, the genotypes with the highest mean Pn were the ones having an intermediate (CMR38-125-77 for the Hot PD) or low LAI (Rayong 9 for the Rainy PD, and CMR38-125-77 for the Cool PD1). Data on variations in canopy structure and photosynthesis potentials of different cassava genotypes in response to seasonal variations may be useful for crop growth modeling and may be employed as a criterion for the selection of suitable genotypes for each growing season.

Genetically Different Isolates of the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis Induce Differential Responses to Stress in Cassava.

Water scarcity negatively impacts global crop yields and climate change is expected to greatly increase the severity of future droughts. The use of arbuscular mycorrhizal fungi (AMF) can potentially mitigate the effects of water stress in plants. Cassava is a crop that feeds approximately 800 million people daily. Genetically different isolates of the AMF R. irregularis as well as their clonal progeny have both been shown to greatly alter cassava growth in field conditions. Given that cassava experiences seasonal drought in many of the regions in which it is cultivated, we evaluated whether intraspecific variation in R. irregularis differentially alters physiological responses of cassava to water stress. In a first experiment, conducted in field conditions in Western Kenya, cassava was inoculated with two genetically different R. irregularis isolates and their clonal progeny. All cassava plants exhibited physiological signs of stress during the dry period, but the largest differences occurred among plants inoculated with clonal progeny of each of the two parental fungal isolates. Because drought had not been experimentally manipulated in the field, we conducted a second experiment in the greenhouse where cassava was inoculated with two genetically different R. irregularis isolates and subjected to drought, followed by re-watering, to allow recovery. Physiological stress responses of cassava to drought differed significantly between plants inoculated with the two different fungi. However, plants that experienced higher drought stress also recovered at a faster rate following re-watering. We conclude that intraspecific genetic variability in AMF significantly influences cassava physiological responses during water stress. This highlights the potential of using naturally existing variation in AMF to improve cassava tolerance undergoing water stress. However, the fact that clonal progeny of an AMF isolate can differentially affect how cassava copes with natural drought stress in field conditions, highlights the necessity to understand additional factors, beyond genetic variation, which can account for such large differences in cassava responses to drought.

Molecular cloning and expression analysis of sucrose phosphate synthase genes in cassava (Manihot esculenta Crantz)

Sucrose phosphate synthase (SPS), a key rate-limiting enzyme in the sucrose biosynthesis pathway in plants, is encoded by a multi-gene family. Until recently, the identification and characterization of the SPS gene family have been performed for dozens of plant species; however, few studies have involved a comprehensive analysis of the SPS family members in tropical crops, such as cassava (Manihot esculenta Crantz). In the current study, five SPS genes (MeSPS1, MeSPS2, MeSPS3, MeSPS4, and MeSPS5) were isolated from cassava, and their sequence characteristics were comprehensively characterized. These MeSPS genes were found distributed on five chromosomes (Chr2, Chr14, Chr15, Chr16, and Chr18). Phylogenetic analysis showed that the MeSPS protein sequences were clustered into three families, together with other SPS sequences from both dicot and monocot species (families A, B, and C). The spatio-temporal expression pattern analysis of MeSPS genes showed a tissue-specific and partially overlapping expression pattern, with the genes mainly expressed in source tissues during cassava growth and development. Correlation analysis revealed that the expression of MeSPS genes correlated positively with root starch content, indicating that the expression of MeSPS genes might accelerate the rate of starch accumulation in the roots of cassava plants.

Morphological, physiological and molecular responses of Indonesian cassava to drought stress

In Indonesia, investigations of drought-tolerant cassava by characterizing the morphological, physiological, and molecular responses have not been carried out. This research was aimed to characterize the morphological, physiological, and molecular features of 10 Indonesian cassava varieties (Adira 1, Malang 1, Cimanggu, Kaspro, Ketan, Litbang UK-2, Malang 4, Malang 6, UJ-3, and UJ-5) under drought stress. 30 days after planting, drought stress was applied by stopping irrigation of plants for 15 days. The plant height, root system, and wilting were measured as morphological responses of cassava. For physiological responses, the percentage of opening stomata, chlorophyll, and hydrogen peroxide (H2O2) content were also investigated. Gene expression of MeGBF3 and MeMSD was evaluated to analyze the response of candidate drought-tolerant genotypes. The studied parameters revealed that drought stress inhibits the growth of cassava. Some genotypes could not survive because the excessive content of H2O2 would be toxic to plant cells and disturb the plant growth. The up-regulated gene expressions of MeGBF3 and MeMSD has correlations with morphological and physiological responses of cassava to drought stress. Adira 1 and Kaspro are thought as drought-tolerant genotypes due to the morphological, physiological, and molecular responses.

Intensification options of small holders’ cassava production in South‐west Nigeria

AbstractCassava (Manihot esculenta Crantz) is a staple food crop in Nigeria, but root yields hardly exceed 10 t ha−1. Intensification of small holders’ cassava production is key to improved food security and income generation. We tested, in two demonstration trials and 20 on‐farm trials, different intensification options: cassava growth type (erect and branching), fertilizer application (with and without), and cassava − legume arrangement (0.5 by 2 m/1 by 1 m spacing of cassava) in demonstration trials. In on‐farm trials, farmers tested a subset of these treatments. The demonstration trials had median cassava yields of about 20 (Akindele village) and 15 (Osunwoyin village) t ha−1. Fertilizer application increased the yield of the erect cassava variety. Cassava intercropped with cowpea [Vigna unguiculata (L.) Walp.], reduced yield and the branching cassava variety produced lower yield than the erect variety. Median cowpea yields were about 1 and 1.5 t ha−1 pod yield. Median yields in the on‐farm trials were about 10 t ha−1. Intercropping with cowpea reduced cassava root yields (on average by 2.4 t ha−1), again, cowpea pod yields of 1−1.5 t ha−1 were attainable. In summary, this study confirmed that intensification measures need to be site and user or farmer specific.

Response of Cassava Crop Cultivated In Sandy Soil To Different Sources of Potassium Fertilizers

Field experiment was carried out in new reclaimed lands at the experimental Station of National Research Centre in Nubaria Region, Behira Governorate, North of Egypt, during the two growing seasons of 2017/2018 and 2018/2019. This studyaimed to enhance cassava(Indonesian cultivar) productivity by using differentsources of potassium fertilizers treatments. Six treatments, i.e.,potassium sulphate as mineral fertilizer, K feldspar + bio fertilizer as bio fertilizer, compound K, Aloe extract as natural fertilizer and Humic acid as organic fertilizer were compared to non-potassium fertilizerapplication (control). The experiments were carried out in a Complete Randomized Blocks Design in four replicates. The characters of vegetative growth, (plant height, leaves number per plant, main stems number per plant, main stem diameter,leaves dry matter, total chlorophyll content and leaf area) total yield per fed., tuber roots characters (average tuber roots number, average tuber roots diameter, average tuber roots length, average tuber roots weight and tuber roots dry matter) and chemical contents of tuber roots (starch % and potassium %)were evaluated.The increment in vegetative growth and productivity of cassava plants was evident with fertilizered plantsby mineral potassium, Aloe extract and Humic acid. On the other hand, decrement in vegetative growth and productivity of cassava was observed withnon-adding potassium fertilizertreatment (control).

The Effect of Different Planting Methods on Growth and Yield of Selected of Cassava (Manihot esculenta) Cultivars

Background: Cassava (Manihot esculenta Crantz) is a source of carbohydrate among the population after maize and rice and highly contributes to food security and livelihood to majority of small scale farmers in Sri Lanka as well as in African continent. The production of these starchy plants is declining due to the problem of low yield, high labor cost, pest and diseases damage and shortage of land. However among the yield limiting factors of cassava, the planting method of stem cuttings which depend on plant cultivar and environmental conditions. Therefore, the present study was carried out to reveal information on the effect of planting methods on the growth and yield attributes of cassava. Methods: The field experiment was conducted at the Farmer’s field in the Batticaloa and laboratory experiment was led in South Eastern University of Sri Lanka which is located in Sri Lanka. The field trail was carried out over a period of four months during from May to September in 2018. The treatments used were three planting positions (Angled, vertical and horizontal) and two cultivars (“cv. Local” and “cv Kirikawadi”) were combined in factorial arrangement and laid out in randomized complete block design with three replications. Result: The result revealed that root yield was significantly (P d” 0.05) affected by the interaction effects of the planting position and varieties. Significant differences were observed among planting methods in all tested variables. Based on the study, storage roots yield of cassava could be enhanced by planting method of angled position.

Causal shoot and root system traits to variability and plasticity in juvenile cassava (Manihot esculenta Crantz) plants in response to reduced soil moisture.

Cassava is an important source of food security and livelihoods for millions of consumers daily. Water deficit conditions are one of the major factors that affect the development of root system architecture (RSA) and consequently, crop productivity, and yet, due to its long maturity periods and bulky storage root systems, RSA studies in cassava are uncommon. The objective of this study was to identify traits that are responsible for the variability and plastic responses of cassava in response to drought at the juvenile stage of growth. Eight cassava genotypes were grown in soil-filled pots under well-watered and droughted conditions for up to 45days and multivariate analyses employed to determine the major contributory traits to variability and the relative distance plasticity index (RDPI) was computed to evaluate plasticity. There were significant genotypic variations for most of the traits measured. Drought generally inhibited root production and development and the degree of inhibition was between 2 and 22%. Regardless of the soil moisture condition, traits which differentiated the RSA included root biomass, root numbers, root branching density, and total root length, and these were also the important contributory traits to variability under well-watered soil conditions. Important contributory traits to variability traits under drought were shoot-related traits such as leaf area and shoot biomass, and also root system traits such as nodal root number, root biomass, diameter and branching density. Phenotypic plasticity was found in most traits where the number, branching density and diameter of upper nodal roots presented the highest RDPI. These traits corresponded with the traits contributing greatly to variation. Plastic responses of cassava to drought were dependent on trait and genotype. It is concluded that upper nodal roots-related traits could have importance in breeding cassava to better tolerate water deficit conditions. The secondary growth and ability to maintain or increase the upper nodal root count or density under limited soil moisture may be related to good growth and yield performance of cassava under drought conditions. Upper nodal roots could be used to screen and select cassava genotypes adapted to drought at the juvenile stage but as a potential indirect selection strategy, the persistence and pertinence of these traits and their relationship with yield and yield components under drought conditions in the field must be confirmed.

Cassava NDVI Analysis: A Nonlinear Mixed Model Approach Based on UAV-Imagery

Imagery data captured by unmanned aerial vehicles ( $${\text{UAVs}}$$ ) have become important tools to study crop growth and development in experimental agronomic research. Moreover, growth curve analysis and nonlinear mixed-effects models ( $${\text{NLME}}$$ ) are increasingly being used to study nonlinear crop responses in the context of repeated measurements. An $${\text{NLME}}$$ to fit the Normalized Difference Vegetation Index ( $${\text{NDVI}}$$ ) based on over-segmented $${\text{UAV}}$$ -imagery of a cassava experimental field is presented. To study the parameters’ variability and error propagation, a resampling analysis and posterior $${\text{NLME}}$$ fit for different sample sizes were performed. High-resolution multispectral images (7 cm resolution) were captured in a cassava experimental field sown under optimal production conditions. $${\text{NDVI}}$$ for individual plants was dynamically calculated by performing a supervised classification based on over-segmented remote images using the simple linear iterative clustering algorithm for near infra-red–red–green bands. A three-parameter logistic function was adopted as a growth curve in function of growing degree days ( $$^\circ {\text{C}}$$ ) and fitted with an $${\text{NLME}}$$ approach. Inherent cassava $${\text{NDVI}}$$ variability due to pixel discretization, plant architecture and cassava growth was found. On average, $${\text{NDVI}}$$ values ranged from 0.35 to 0.40 for first development stages (295, 340 and 372 $$^\circ {\text{C }}$$ days) until 0.77 for maturity (1606 $$^\circ {\text{C }}$$ days). $${\text{NDVI}}$$ plant variability was correctly addressed considering the three parameters as random effects showing small root-mean-square error. Resampling analysis proved that a suitable accuracy parameter estimation can be performed with fewer individuals (plants) which might represent an agricultural experimental design with fewer experimental units. While the application of $${\text{UAV}}$$ imaging and nonlinear mixed models in determining $${\text{NDVI}}$$ curves is a relevant methodological framework, further research towards the optimization of experiment sample size is required.

Coupling Compost from Chicken Manure and Inorganic Fertilizer to Improve Cassava (Manihot esculenta Crantz) Growth and Yield on a Ferralitic Soil in Côte d‘Ivoire

This study aimed to evaluate the effect of compost from chicken manure, NPK fertilizer and the mixture of both fertilizers on agronomic parameters of four varieties of cassava (Yacé, Bonoua, Six mois and Alleda agba) in Côte d‘Ivoire. The field experiment was carried out under a randomized complete block design with three replicates on a ferralitic soil during two season-cycles. The results showed that the different fertilizers stimulated plants growth and tuberous roots production. The highest number of stems (3) and leaves (66) was obtained with the mixture of NPK and compost applied on the variety “Bonoua”. All varieties that received the compost mixed with NPK produced more leaves with a dominance of the Bonoua variety (65.57). The highest number of tuberous roots (5.58), the heaviest weight per root (6.13 kg) and the highest yield (61.37 t/ha) were obtained while using the mixture of compost and NPK as fertilizer and “Bonoua” as variety. Thus, mixing compost from chicken manure and NPK can be recommended to improve cassava productivity in Côte d'Ivoire on a ferralitic soil.

Effect of Soil Moisture and Determination of Critical Soil Moisture Contents of Cassava

The aims of this research were to investigate the effects of soil moisture on cassava growth and physiological processes and to determine the critical soil moisture contents. To fulifll the research objectives, cassava was grown under five levels of soil moisture, including 50, 40, 30 and 20% of soil available water holding capacity (AWHC) along with control (no irrigation). Physiological traits and plant growth parameters were measured. The results showed that cassava grown under 50% of AWHC exhibited the highest photosynthesis rate, stomatal conductance, predawn leaf water potential and chlorophyll activity. All physiological traits decreased significantly when the moisture content was less than 40 and 20% of AWHC in sandy clay loam and loamy sand soil, respectively. Predawn leaf water potential was used to determine the critical point of soil moisture. It was found that the critical soil moisture contents were 39.0 and 15.7% of AWHC in sandy clay loam and loamy sand soil, respectively.

Evaluation of K efficient genotypes for improving growth, tuber yield and starch content of cassava (Manihot esculenta Crantz.)

Evaluation of K efficient genotypes for improving growth, tuber yield and starch content of cassava (Manihot esculenta Crantz.)

Four years assessment of Cassava Bacterial Blight expression according to weather conditions in Côte d’Ivoire

Cassava growth in Cote d’Ivoire is affected by the variation in weather conditions and various pests and diseases. Cassava Bacterial Blight is a particularly destructive disease influenced by weather conditions which can lead to 100% yield loss. In order to provide sustainable control strategies, it is essential to understand the occurrence and the behaviour of the disease in the different ecological zones in Cote d’Ivoire. Surveys were carried out in cassava fields from 2014 to 2017 in the seven Ivorian agro-ecological zones. These fields were assessed for the disease presence/absence, the severity index (SI) and the disease incidence (DI). Weather data were provided by weather stations in Cote d’Ivoire. The results of this study showed that the disease was present in mainly the agro-ecological zones 1, 2, 3 and 4 representing the higher yield potential zones of cassava production. Disease expression was variable depending on the years and the prevalent weather conditions in each agro-ecological zone. The high SI and DI were found in the agro-ecological zones 1, 4 and 6. The disease was able to reach rates of 100% in many zones for both SI and DI with dieback incidence mainly in the agro-ecological 1, 4 and 6 zones under unfavourable (low rainfall, RH, NRD) and favourable conditions. It is therefore urgent to implement control strategies such as such as the integration of new cassava varieties, screening under different agro-ecological zones and improvement of varieties in order to provide resistant varieties to the farmers.

Effect of bio-stimulants foliar applications on growth, yield, and product quality of two Cassava cultivars

BackgroundCassava is a major staple food crop for the people in tropical and sub-tropical areas, a non-traditional vegetable root crop in Egypt. It has important industrial raw materials for the production of starch, alcohol, pharmaceuticals, and livestock feed. The current study is evaluating two cassava cultivars: American and Brazilian types under three bio-stimulants: glutamine, lysine, and active dry yeast, as foliar applications. Vegetative growth characters, tuber yield, and its quality as well as chemical contents of cassava tubers were evaluated.ResultsThe results showed that American cassava cultivar recorded the highest vegetative growth characters (plant height, leaves number, main stems, lateral branches, leaf area, and chlorophyll content), tuber yield (number and weight), and tuber quality (length, diameter, dry matter, and tubers-shoots ratio) as well as chemical composition (starch, total carbohydrates, N, P, and K). The foliar application of glutamine at the rate of 200 mg/L increased vegetative growth characters and tuber yield as well as tuber quality and improved chemical contents of cassava tubers. On the contrary, the lowest values of cassava growth and its productivity as well as chemical composition were associated to Brazilian cultivar when foliar sprayed by yeast at the concentration of 2 g/L.ConclusionFrom this study, it could be concluded that American type of cassava is the most suitable under Egyptian conditions, which ranked the first in all vegetative growth characters, tuber yield, tuber quality, and chemical composition, with foliar sprayed by glutamine at the rate of 200 mg/L.

Effect of Biochar Application on the Growth of Cassava and Maize, Maize Yield and Soil Erosion in Cassava+Maize Intercropping System

Effect of Biochar Application on the Growth of Cassava and Maize, Maize Yield and Soil Erosion in Cassava+Maize Intercropping System

SOIL LOSS AND CASSAVA YIELD UNDER RIDGE TILLAGE IN HUMID TROPICAL CLIMATE OF SUMATERA, INDONESIA

Erosion is one of problem threatens the soil resource caused soil degradation. Applying the ridges system and organic fertilizer contributes to suppressing runoff and erosion. This study aims to determine the effect of applying different ridges system and the organic fertilizer on the runoff, soil erosion, nutrients loss of soil, nutrient enrichment ratio, starch content, growth, and yield of cassava on 12.5% slope land. The research was conducted at the field experiment, University of Lampung, under a humid tropical climate. This study used a Randomized Complete Block Design, which was arranged factorially with two factors, ridges system and organic fertilizer (organonitrofos) and four replications. Factor one is consists of G1 (ridges in the same direction with the slope) and G2 (ridges in the opposite direction with the slope), while factor two is consists of P0 (Organonitrofos 0 tons/ha) and P1 (Orgononitrofos 20 tons/ha). The results showed that the application of the ridges in the opposite direction with the slope significantly reduces the runoff 42.63%, soil erosion 61.68%, and suppress nutrient loss of N-total by 61.85%, P-available by 57.92%, K-total by 80.41% and C-organic by 61.22%, compared to ridges in the same direction with the slope. However, ridges systems do not give a significant difference to starch content, growth, and cassava yield. Physical obstacles formed by ridges in the opposite direction with the slope will force water to infiltrate into the soil so that the runoff rate, erosion, and nutrients loss can be reduced significantly. In reverse, the organic fertilizers do not affect all variables. The ridges system and the organic fertilizer did not significantly affect the starch content, growth, and yield of cassava. That caused by the application of synthetic fertilizers at the same dose (standard dose for planting cassava) in each experimental unit that fertilizer already enough to grow optimally.

Leaf area development and yield of cassava in response to pruning of shoots and the late supply of nitrogen and potassium

AbstractThis study evaluated leaf area development, leaf nutritional content, and yield of pruned/unpruned cassava supplied with nitrogen (N) and potassium (K) during its second vegetative cycle. Two field experiments were conducted in a randomized complete‐block design with split‐plots and four replications. The treatments consisted of four management approaches that combined pruning/not pruning with or without K as the main plot and four N application rates (0, 50, 100, and 200 kg ha−1 N) as the subplots. The results revealed that an evaluation of the nutritional status of cassava during its second vegetative cycle should be considered if shoot pruning has been conducted because pruned plants had higher concentrations of N, P, and K in their leaves, and unpruned plants exhibited leaves with higher Ca, Fe, and Mn concentrations. Pruning of cassava shoots during the autumn/winter resting phase did not negatively affect root yield and may represent a recommended management practice for cassava cultivation. In soils with a medium level of K availability, K provision during the second cassava growth cycle is unnecessary because the application of K did not increase leaf reconstitution or yield components in either pruned or unpruned plants. The late application of N improved the nutritional status of cassava plants and increased their leaf area during the second growth cycle. Cassava root, starch, and flour yields increased in a linear fashion in response to the late application of N.

Is Cassava (Manihot esculenta Crantz) a Climate “Smart” Crop? A Review in the Context of Bridging Future Food Demand Gap

Climate change and its impact on agriculture are one of the ongoing research areas, and the major task among agricultural managers is to meet the food demand in the future in the context of the production gap of major food grain crops. Literature analysis is carried out to understand the climate resilience of cassava, one of the major tuber crops and is considered to bridge the food demand gap in the near future. Systematic analysis of literature includes influence of changing environmental parameters such as temperature, solar radiation, photoperiod, air humidity, soil water deficit, salinity, elevated ozone and CO2, combined effects of elevated CO2 with temperature, water deficit and salinity to the growth and yield of cassava along with its resilience to biotic stresses and its climate suitability. Studies indicate cassava can tolerate a temperature level of up to 40 °C, and thereafter the rate of photosynthesis decreases. Cassava can be cultivated in regions with variations in solar radiation without much compromise in its yield in the context of global dimming of sunshine duration. The resilience to water stress and air humidity variations are adapted by reducing stomatal conductance without influencing the rate of photosynthesis. Cassava has also an inbuilt mechanism to cope with water scarcity by leaf drooping. Already established cassava can tolerate a salinity level of up to 150 mM and the younger ones can tolerate up to a level of 40 mM. Studies also indicate a strong positive influence of elevated CO2 of up to 700 ppm on the rate of photosynthesis and yield of cassava. Elevated CO2 enhances the resilience of cassava to water stress and salinity. Similarly, the combined effect of elevated CO2 and higher temperatures also increases the yield attributes of cassava. These all indicate the resilience of cassava to the changing climate and it ensures as an insurance crop as well as food security crop in the near future. Studies show its resilience to biotic stresses as well. Climate suitability studies also show its suitability in the present locations in the near future as well as its adaptation to other areas. However, the research gap is identified in areas of influence of elevated ozone on growth characteristics of cassava. This study also recommends identifying the extent of tolerance level of cassava to the influence of the combined effect of salinity and elevated CO2. Further, researchers need to concentrate on developing biotic as well as abiotic stress-tolerant genes in cassava varieties to increase its production irrespective of the changing climatic conditions.

Growth Response of Cassava to Deficit Irrigation and Potassium Fertigation during the Early Growth Phase

Cassava (Manihot esculenta Crantz) experiences intermittent water deficit and suffers from potassium (K) deficiency that seriously constrains its yield in the tropics. Currently, the interaction effect between deficit irrigation and K fertigation on growth and yield of cassava is unknown, especially during the early growth phase. Therefore, pot experiments were conducted under controlled greenhouse conditions using cassava cuttings. Treatments initiated at 30 days after planting included three irrigation doses (30%, 60%, 100% pot capacity) and five K (0.01, 1, 4, 16, and 32 mM) concentrations. The plants were harvested 90 days after planting. Decreasing irrigation dose to 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with full-irrigated plants. Lowering the K concentration below 16 mM reduced the values further. Notably, growth and yield were decreased the least compared with optimal, when irrigation dose was decreased to 60% together with 16 mM K. The results demonstrate that deficit irrigation strategies could be utilized to develop management practices to improve cassava productivity by means of K fertigation under low moisture conditions.