Response of potato (Solanum tuberosum L.) cultivars to drought stress under in vitro and field conditions

Background Potato (Solanum tuberosum L.), the world’s third most important crop, is frequently thought to be sensitive to moderately sensitive to drought, and yield has fallen considerably over consecutive stress periods. Drought produces a wide range of responses in potato, from physiological alterations to variations in growth rates and yield. Knowledge about these responses is essential for getting a full understanding of drought-tolerance mechanism in potato plants which will help in the identification of drought-tolerant cultivars. Results A set of 21 commercial potato cultivars representing the genetic diversity in the Middle East countries market were screened for drought tolerance by measuring morpho-physiological traits and tuber production under in vitro and field trials. Cultivars were exposed to drought stress ranging from no drought to 0.1, 0.2 and 0.3 mol L−1 sorbitol in in vitro-based screening and 60, 40 and 20% soil moisture content in field-based screening. Drought stress adversely affected plant growth, yield and cultivars differed for their responses. Shoots and roots fresh weights, root length, surface area of root, no. of roots, no. of leaves, leaf area, plant water content %, K+ content, under in vitro drought treatments and shoots fresh and dry weights, no. of tubers and tuber yield under field drought treatments were examined and all decreased due to drought. The stress tolerance index decreased with increasing drought in examined cultivars; nevertheless, it revealed a degree of tolerance in some of them. Grouping cultivars by cluster analysis for response to drought resulted in: (i) a tolerant group of five cultivars, (ii) a moderately tolerant group of 11 cultivars, and (iii) a sensitive group of five cultivars. Furthermore, stress-related genes, i.e., DRO, ERECTA, ERF, DREB and StMYB were up-regulated in the five cultivars of the tolerant group. Likewise, the stomatal conductance and transpiration explained high correlation with the tuber yield in this group of cultivars. Conclusion The diversity in germplasm indicated that potato cultivars can be developed for production under certain degrees of drought. Some cultivars are good candidates to be included in drought-tolerant breeding programs and recommended for cultivation in drought-stricken regions. Graphical Abstract

Growth and production of potato mini tubers (Solanum tuberosum L.) in the aeroponic system by root zone treatment and concentration of leaf-fertilizer

This study was conducted to increase the growth of potato and its mini tuber yield by root zone treatment and the concentration of leaf-fertilizer in the aeroponics system. This research was done at Experimental Farm of The Agriculture Faculty, Universitas Syiah Kuala from October 2019 until July 2020. There were 2 levels of root zone treatment; control (without cooling) and root zone cooling. Meanwhile the concentration of leaf-fertilizer consists of 5 levels; control, 500 ppm, 1000 ppm, 1500 ppm and 2000 ppm. The results showed that the root zone treatment significantly affected the plant dry weight. The heaviest plant dry weight obtained from the plant grown in root zone cooling treatment. The concentration of leaf-fertilizer very significantly affected the plant dry weight, which the best concentration of 500 ppm produced 751.28 mg plant-dry-weight. There was a very significant effect at a combination of root zone treatment and concentration of leaf-fertilizer on plant dry weight, which the best treatment was found in a combination of root zone cooling and 500 ppm concentration of leaf-fertilizer. The plant with that treatment produced mini tuber, while the others did not.

Response of yam varieties to soil moisture regime in Southwestern Nigeria

A field experiment was conducted on varietal response of white yam to moisture regime in Abeokuta. The experiment comprised three varieties of yam (Efuru, Ise-osi and Oniyere), three mulching options (grass, polythene and unmulched), and two planting dates (early and late). Treatments were replicated three times using RCBD lay-out. Model for selecting planting date involved relating potential evapotranspiration (PE) to precipitation (P) in the form of 0.1PE<P < 0.5PE, partitioned for attaining optimal planting date into early {T1= Σ(P-0.1PE) ≤ 0} and late {T2 = Σ(P-0.5PE) ≤ 0}, respectively. For humid period defined by P> PE, the physiological parameters and moisture agro-climatic indices measured during phenological stages of yam grown were analyzed with respect to treatments. Result showed that T1 defined as Σ(P-0.1PE) ≤ 10 mm appeared as the best model that significantly (P < 0.05) influenced emergence rate, phenological growth and tuber yield. All yam varieties evaluated were suitable for planting with respect to yield. Efuru and Ise-osi synchronized perfectly with Actual Water Availability and produced good vegetative growth with LAI of 1.08 and 0.91 leading to higher tuber yield of 12 and 11.64 tonnes ha-1, respectively. Grass mulch had tuber yield, 4-6 tonnes ha-1greater than the polythene and unmulched plots in all varieties. Mulching significantly (P< 0.05) increased tuber yield, 6-8 tonnes ha-1than the unmulched. Conclusively, early planting with grass mulch increased tuber yield.

Exploring the Bush yam (Dioscorea praehensilis Benth) as a Source of Agronomic and Quality Trait Genes in White Guinea yam (Dioscorea rotundata Poir) Breeding

Yam (Dioscorea spp.) is an important food security crop in the tropics and subtropics. However, it is characterized by a narrow genetic base within cultivated and breeding lines for tuber yield, disease resistance, and postharvest traits, which hinders the yam breeding progress. Identification of new sources of desirable genes for these traits from primary and secondary gene pools is essential for this crop improvement. This study aimed at identifying potential sources of genes for yield and quality traits in a panel of 162 accessions of D. praehensilis, a semi-domesticated yam species, for improving the major yam species, D. rotundata. Significant differences were observed for assessed traits (p < 0.05), with D. praehensilis genotypes out-performing the best D. rotundata landraces for tuber yield (23.47 t ha−1), yam mosaic virus (YMV) resistance (AUDPC = 147.45), plant vigour (2.43) and tuber size (2.73). The study revealed significant genotypic (GCV) and phenotypic (PCV) coefficients of variance for tuber yield, YMV severity score, and tuber flesh oxidation. We had also a medium-to-high broad-sense heritability (H2b) for most of the traits except for the dry matter content and tuber flesh oxidation. This study identified some promising D. praehensilis genotypes for traits such as high yield potential (WNDpr76, CDpr28, CDPr7, EDpr14, and WNDpr63), resistance to YMV (WNDpr76, CDpr7, EDpr14, CDpr28, and EDpr13), high dry matter content (WNDpr76, CDpr28, and WNDpr24), low tuber flesh oxidation (WNDpr76, CDpr5, WNDpr31, CDpr40, and WNDpr94) and high number of tubers per plant (WNDpr76, CDpr7, CDpr68, CDpr29, and CDpr58). These genotypes could, therefore, be employed in breeding programmes to improve the white Guinea yam by broadening its genetic base.

Estimation of Genetic Variability, Heritability and Genetic Advance in Potato (Solanum tuberosum L.) Genotypes for Tuber Yield and Yield Related Traits

Potato is a high potential food security crop in Ethiopia. Genetic variability is the basis of all crop improvement programs. The study was conducted at Adet in 2018 with the objective of assessing the extent and pattern of genetic variability of potato genotypes for yield and yield related traits. A total of 36 potato genotypes were evaluated for 18 quantitative traits in simple lattice design. The analysis of variance revealed that highly significant difference among the tested potato genotypes for all quantitative traits except stem number per hill. The phenotypic coefficient of variation was ranged from 4.56 to 56.01% (for specific gravity and unmarketable tuber yield ha-1 respectively) and the genotypic coefficient of variation was ranged from 2.32 to 40.66% (specific gravity and late blight severity percentage respectively). Days to attain 50% emergence, leaf area index, number of marketable and total tubers per plant, marketable and total tuber yield ha-1, and late blight severity percentage showed high heritability and high genetic advance as percent of mean. Most of the traits had high phenotypic coefficient of variation and genotypic coefficient of variation; and coupled high heritability with high genetic advance as percent of mean. Traits having high heritability and high genetic advance as percent of means is effective for simple selection.

Crop Cycle Length Determines Optimal Transplanting Date for Seedlings from Hybrid True Potato Seeds

The technology of hybrid breeding in diploid potatoes creates opportunities to design novel and improved cultivation systems based on hybrid true potato seeds. A promising cultivation pathway to produce seed or ware tubers is by transplanting greenhouse-raised seedlings into the field. This study explored the effects of transplanting date and seedling age on tuber yield, using greenhouse-raised seedlings. Field trials with experimental hybrid genotypes were conducted in three consecutive years. In 2017 and 2018, 4- and 6-week-old seedlings were transplanted at four dates: March, April, May and June. In 2019, transplanting dates included April, May and June and seedling age was 5 weeks. In 2018, the March planting experienced severe frost during the initial field period resulting in crop failure. In 2017 and 2019, plants could withstand shorter and less severe frost events. Seedling age did not significantly affect tuber parameters. Transplanting in June resulted in lower marketable yield (> 28 mm) compared with earlier transplanting dates when crops were harvested in September. At full crop senescence, no differences in marketable yield were observed. The optimal transplanting window, taking into account weather-related risks, is approximately between early April and end May. For some genotypes, crop cycle length was observed to be a more important yield-determining factor than transplanting date.

Response of Potato (Solanum tuberosum L.) Varieties to Blended Nitrogen, Phosphorus and Sulfur Fertilizer Rate at Kokate, Southern Region

Low production and productivity of potato in Ethiopia is associated with poor soil fertility and limitation of high yielding crop variety. Matching high yielding cultivar with optimum fertilization of balanced nutrients is of paramount important to boost tuber yield of potato. Hence, a field experiment was conducted during 2019/20 cropping season at Kokate testing site of Areka Agricultural Research Center in southern Ethiopia in order to evaluate the response of potato varieties to NPS fertilizer rates. Treatments used in the study were two improved varieties of potato (Gudane and Belete) one local cultivar with six rates of blended NPS (0, 50, 100, 150, 200 and 250 kg/ha NPS) combined in factorial and laid out in a randomized complete block design with three replications. As this investigation indicated that at all rates of NPS fertilizer, improved varieties out yielded the local cultivar Asmara with relative superiority of variety Belete for marketable tuber yield. Economic analysis revealed that the highest net benefit of 276326 Birr/ha with marginal rate of return (MRR) 3762% was obtained from variety Belete at NPS fertilizer rate of 200 kg/ha followed by variety Gudane at the same fertilizer rate with net benefit of 270350 Birr/ha and MRR of 3372%. Based on this finding, varieties Belete and Gudane could be used for production at NPS fertilizer rate of 200 kg/ha near study area and similar agro-ecologies.

Effect of Integrated Nutrient Management on Plant Growth and Tuber Yield of Dahlia (Dahlia variabilis) cv. Kenya White

The experiment was carried out at Experimental field, Department of Horticulture, Sam Higginbottom Institute of Agriculture Technology and Sciences [formerly known as Allahabad Agriculture Institute Deemed University, AAI-DU] during the Spring season 2014-2015. The experiment consists of Thirteen treatments viz., (T0) Control-RDF (100:120:100 N P K kg ha-1,), (T1) 75% RDF + AZ@ 2.5 kg ha-1,, (T2) 75% RDF + FYM @ 10 ton ha-1, (T3) 75% RDF + VC@ 10 ton ha-1, (T4) 75% RDF + AZ @ 2.5 kg/ha +FYM @ 10 ton ha-1+VC @ 10 ton ha-1, (T5) 50% RDF +AZ@ 2.5 kg ha-1, (T6) 50% RDF + FYM@ 10 ton ha-1, (T7) 50% RDF + VC@ 10 ton ha-1, (T8) 50% RDF + AZ @ 2.5 kg ha-1+FYM @ 10 ton ha-1+VC @ 10 ton ha-1, (T9) 25% RDF + AZ@ 2.5 kg ha-1, (T10) 25% RDF + FYM@ 10 ton ha-1, (T11) 25% RDF + VC@ 10 ton ha-1+, (T12) 25% RDF + AZ @ 2.5 kg ha-1+FYM @ 10 ton ha-1+VC @ 10 ton ha-1. The treatments were replicated thrice in a Randomized Complete Block Design. The results revealed that Plants treated with 75% RDF + AZ @ 2.5 kg/ha +FYM @ 10 t/ha +VC @ 10 t/ha (T4) significantly recorded maximum vegetative and Tuber yield attributes like plant height (91.87 cm), plant spread (92.38 cm), Number of Branches per plant (7.27), number of leaves per plant (26.53), number of tubers per plant (4.80), maximum tuber weight (958.53) and Maximum tuber yield per plant was recorded in T4 (75% RDF + AZ @ 2.5 kg/ha +FYM @ 10 t/ha +VC @ 10 t/ha) (43.33g) followed by T3 (75% RDF + VC @ 10 t/ha) (40.95g).