Crops, Volume 2, Issue 2 (June 2022) – 8 articles

The southwestern regions of the Kingdom of Saudi Arabia (KSA) are geographically and agriculturally diverse. Over millennia, crop production in these regions has evolved to use renewable water resources sustainably. This study analysed environmental and crop production data for 58 governorates in KSA’s four southwestern regions: Al Baha, Aseer, Jazan and Makkah. The biplot analysis generated six clusters of cropping systems: sorghum, cereals, dates, watermelon, vegetables and fruits, and mixed. The main biophysical factors shaping these systems are topography, altitude, rainfall, air temperature and soils. Sorghum, grown on more than half of the cultivated land, dominates the two main systems. Fruits (subtropical and temperate) and open field vegetables are important elements in most systems. The main challenge is combining a moderate use of water with greater crop diversity. Cereals consume relatively little water, but their dominance within the systems reduces overall diversity. Another important issue is the low-input technologies used to cultivate sorghum and other cereals. Landraces or older varieties are planted and little, if any, fertilizers and pesticides are applied. The introduction of sustainable intensification packages is needed, which can begin with making improved varieties accessible to farmers, promoting conservation agriculture, and integrated pest management practices. Full article

Protected cropping offers a way to bolster food production in the face of climate change and deliver healthy food sustainably with fewer resources. However, to make this way of farming economically viable, we need to consider the status of protected cropping in the context of available technologies and corresponding target horticultural crops. This review outlines existing opportunities and challenges that must be addressed by ongoing research and innovation in this exciting but complex field in Australia. Indoor farm facilities are broadly categorised into the following three levels of technological advancement: low-, medium- and high-tech with corresponding challenges that require innovative solutions. Furthermore, limitations on indoor plant growth and protected cropping systems (e.g., high energy costs) have restricted the use of indoor agriculture to relatively few, high value crops. Hence, we need to develop new crop cultivars suitable for indoor agriculture that may differ from those required for open field production. In addition, protected cropping requires high start-up costs, expensive skilled labour, high energy consumption, and significant pest and disease management and quality control. Overall, protected cropping offers promising solutions for food security, while reducing the carbon footprint of food production. However, for indoor cropping production to have a substantial positive impact on global food security and nutritional security, the economical production of diverse crops will be essential. Full article

Categorical data derived from qualitative classifications or countable quantitative data are common in biological scientific work and crop breeding. Categorical data analyses are important for drawing correct inferences from experiments. However, categorical data can introduce unique issues in data analysis. This paper discusses common problems arising from categorical variable analysis and modeling, demonstrates the issues or risks of misapplying analysis, and suggests approaches to address data analysis challenges using two data sets from alfalfa breeding programs. For each data set, we present several analysis methods, e.g., simple t-test, analysis of variance (ANOVA), split plot analysis, generalized linear model (glm), generalized linear mixed model (glmm) using R with R markdown, and with the standard statistical analysis software SAS/JMP. The goal is to demonstrate good analysis practices for categorical data by comparing the potential ‘bad’ analyses with better ones, avoiding too much reliance on reaching a significant p-value of 0.05, and navigating the morass of ever-increasing numbers of potential R functions. The three main aspects of this research focus on choosing the right data distribution to use, using the correct error terms for hypothesis test p-values including the right type of sum of the squares (Type I, II, and III), and proper statistical models for categorical data analysis. Our results show the importance of good statistical analysis practice to help agronomists, breeders, and other researchers apply appropriate statistical approaches to draw more accurate conclusions from their data. Full article

Sporisorium reilianum causes head smut in sorghum. A total of 36 Senegalese sorghum accessions comprised of sorghum lines that have not been explored with response to pathotype 5 of S. reilianum were evaluated with 3 different treatments. First, seedling shoots were inoculated while still in soil with teliospores in agar, and then submerged under water at 4 days post inoculation. Signs of infection (noticeable spots) on the first leaf were observed up to 6 days post submergence. Second, seedlings at the same stage were inoculated by placing the teliospore impregnated agar around the stem in pots, moved to a greenhouse and grown to full panicle development stage. Third, seedings were inoculated via syringe inoculation in the greenhouse. Although soil inoculated seedlings grown in the greenhouse did not result in systemic infection as determined by lack of symptoms at panicle exsertion, 88.9% of tested cultivars showed systemic infections when syringe inoculated in the greenhouse. Inoculation of seedlings maintained under water led to broad range of noticeable spots that are assumed to be potential infection sites based on a previous study. In addition, seedling inoculation led to slightly upregulated expression of chitinase and PR10, genes that are associated with defense in aerial parts of plants. Full article

The present study investigated the distribution status and biodiversity of Trichoderma species surveyed from coffee rhizosphere soil samples from Ethiopia and their potential for biocontrol of coffee wilt disease (CWD) caused by Fusarium xylarioides. Trichoderma isolates were identified based on molecular approaches and morphological characteristics followed by biodiversity analysis using different biodiversity indices. The antagonistic potential of Trichoderma isolates was evaluated against F. xylarioides using the dual confrontation technique and agar diffusion bioassays. A relatively high diversity of species was observed, including 16 taxa and 11 undescribed isolates. Trichoderma asperellum, T. asperelloides and T. longibrachiatum were classified as abundant species, with dominance (Y) values of 0.062, 0.056 and 0.034, respectively. Trichoderma asperellum was the most abundant species (comprising 39.6% of all isolates) in all investigated coffee ecosystems. Shannon’s biodiversity index (H), the evenness (E), Simpson’s biodiversity index (D) and the abundance index (J) were calculated for each coffee ecosystem, revealing that species diversity and evenness were highest in the Jimma zone (H = 1.97, E = 0.76, D = 0.91, J = 2.73). The average diversity values for Trichoderma species originating from the coffee ecosystem were H = 1.77, D = 0.7, E = 0.75 and J = 2.4. In vitro confrontation experiments revealed that T. asperellum AU131 and T. longibrachiatum AU158 reduced the mycelial growth of F. xylarioides by over 80%. The potential use of these Trichoderma species for disease management of F. xylarioides and to reduce its impact on coffee cultivation is discussed in relation to Ethiopia’s ongoing coffee wilt disease crisis. Full article

Legume seeds are often sown on standing rice crops a few weeks before rice harvest (relay cropping). Seeds cannot germinate in waterlogged soil under relay sowing as oxygen is depleted. However, seeds may survive under soil waterlogging if the seeds can initiate anaerobic respiration, have a large seed reserve such as carbohydrates, perform a slow water uptake during imbibition and are small in size. An example of a seed crop that can initiate anaerobic respiration is rice. The seed embryo of rice can use an alcoholic fermentation pathway from carbohydrates to produce enough energy to germinate. In legumes, seeds with a slow imbibition rate were more waterlogging tolerant than seeds with a rapid rate. This is likely due to seeds with low imbibition rates having less electrolyte leakage than seeds with a rapid imbibition rate during germination under waterlogging. A small amount of oxygen may remain on the surface of waterlogged soil. Small seeds can use the small amount of oxygen on the surface of waterlogged soil to germinate. However, large seeds often fail to use the oxygen on the surface of waterlogged soil to germinate because only a small part of large seeds remain on the surface of waterlogged soil. Therefore, small seeds are more adapted to soil waterlogging than large seeds under relay cropping. This review is focused on the physiological adaptation of legume seeds under low oxygen concentration during soil waterlogging. Full article

Jaltomata procumbens (Cav.) J. L. Gentry presents seed dormancy mechanisms in its two populations, erect and decumbent, that make its germination and obtaining of plants difficult. Potassium nitrate (KNO₃) is used as a seed germination promoter by soaking in an osmotic solution. The objective was to break the dormancy of Jaltomata seeds by evaluating KNO₃. Treatments included: 2 populations (erect and decumbent), 2 soaking times (4 and 6 days) in 2 concentrations of KNO₃ solution (0.1% and 0.2%) and in distilled water used as a control. Days of germination including starting (DGS) and ending (DGE), energy period (EP), germination energy (GE), germination percentage (GP) and rate (GR) were measured. The erect population presented a more uniform germination and a lower number of DGS and DGE as well as 100% germination with the highest GR (2.56 seeds day⁻¹). No statistical differences were observed between KNO₃ and control; however, the positive effect of the KNO₃ and 4 days of soaking on the germinated seed was observed. The decumbent population exhibited a more variable germination; however, the same trend of the solution type and soaking days was observed, reaching 93.1 GP. Considering the economic and accessibility aspects of substances that promote germination on J. procumbens, distilled water imbibition and KNO₃ are recommended to accelerate the germination process. Full article

Microwave technology has wide applications, including extraction of active compounds in biomass and compost for agricultural use. A study was carried out to determine the effects of microwave power level from 0 (control) to 1000 W on the properties and active microbial groups in vermicast, and how it may impact the photosynthesis, plant growth, and yield of kale (Brassica oleracea var. sabellica) ‘Red Russian’. Heat accumulation in the vermicast increased rapidly to a peak of 86 °C at 400 W before declining to 68 °C at 1000 W. Vermicast water loss increased exponentially up to 800 W before declining. The C:N ratio of the vermicast was reduced at ≥600 W while the pH remained the same. In a 2D-principal component analysis biplot, vermicast treated at 600, 800 and 1000 W were associated with Gram-positive (G+), GGram-negative (G−), G + G− bacteria, protozoa, and fungi groups while the 0, 200, and 400 W treated vermicast were associated with eukaryotes. However, the trend for total microbial mass was 200 W = 400 W > 0 W > 600 W = 800 W = 1000 W. Kale leaf anthocyanin, chlorophylls, and carotenoids were significantly (p = 0.001) increased by the 400 W or 600 W treatment compared to the other treatments. Stomatal conductance, transpiration, and photosynthesis rates were increased by the 400 W followed by the 600 W. As a result, yield of kale grown in the 400 W microwaved vermicast was the highest. Future studies will explain the functions of specific microbial populations and elemental composition in microwaved vermicast. Full article