Impact of partial root-zone drying on growth, yield and quality of tomatoes produced in green house condition

Water resources are limited for irrigation worldwide especially for the arid and semi-arid regions; therefore, there is an urgent need to reassess an alternative technique for conventional irrigation. Partial root-zone drying (PRD) is considered a new water-saving irrigation technique which has been tested for some crop species. The PRD technique simply requires wetting half of the rooting zone and leaving the other half dry, thereby utilizing reduced amount of irrigation water. The wetted and dry sides are interchanged in the subsequent irrigations. The focus of this article is to evaluate the effect of PRD on growth, yield and quality of tomatoes as compared to conventional irrigation. To evaluate the effect of PRD, a greenhouse experiment was conducted where two irrigation treatments were tested during a 160-day growing period: (1) control treatment where drip irrigation was applied to both sides of the plants; (2) PRD treatment in which half of the irrigation water in drip irrigation was given alternately only to one side of the root system with each irrigation. PRD treatment had 15% and 7% decreases in shoot fresh weight and leaf area of plant, respectively; however, PRD had 20% higher fruit per cluster and 18% increase in fruit production in comparison to the control treatment. No significant difference was detected on fruit size between PRD treated plants and control plants. But, fruits from PRD treated plant exhibited better appearance, higher lycopene content, firmness, total soluble solid (TSS), and TSS/titratable acidity (TA) ratio than control ones. Fruit from control treatment contained higher chlorophyll content than fruit from the PRD treatment. Postharvest storage results indicated that higher percentage of rot and chilling injury were observed in control fruits than PRD treated fruits. The results of this study indicated that PRD is a promising water saving irrigation technique which is able to produce higher yield and better quality tomatoes than conventional drip irrigation

Critical Review on Plant Micropropagation of Ethiopian Plants Reported So Far: Existing Gaps, Required Standardization, and Future Research Direction

Plant micropropagation research in Ethiopia requires concerted efforts to meet desired levels of application for sustainable utilization of the country's diverse plant genetic resources. The purpose of the present review is to provide an update on the results of plant micropropagation conducted so far in Ethiopia. It assessed their strengths and identified gaps in order to standardize research methods and indicate future research directions. Two cereals, three oil crops, three spices, five medicinal plants, two high-value crops, six fruit plants, nine root crops, and one endangered multipurpose shrub were reviewed. The assessment of previously published research was carried out in terms of methods used in the selection of ex plants and their disinfestations, culture vessels, and media used with a variety of combinations and concentrations of plant growth regulators, macro- and micronutrient requirements, culture environments, and genetic stability of regenerated plantlets. Further assessments include the utilization of plant growth-promoting microbes and applications of "omics" research in order to establish standardized, efficient, and cost-effective micropropagation techniques. The findings of the assessments are summarized and current advances are highlighted, along with recommendations for future plant micropropagation studies in the country

Genetic Divergence Analysis In Indigenous Maize Germplasms (Zea Mays L.)

Assessing the genetic diversity is a pre-requisite for any breeding programme to select appropriate parents forhybridization. A total of 105 adapted maize germplasms lines were subjected to Mahalanobis D2analysis based on fourcharacteristics viz., plant height, cob height, cob length and number of kernel rows per cob in order to assess the genetic divergenceamong them. The analysis grouped the genotypes into four clusters. Among them, cluster IV was the largest with 53 genotypesfollowed by cluster II with 32 genotypes. The percent contribution of each traits for total divergence revealed the highestcontribution from Plant height followed by ear length, number of kernel rows per cob and ear height. The maximum intra-clusterdistance was observed in cluster II followed by cluster I and IV. The highest inter cluster distance was observed between cluster IIIand cluster IV followed by cluster I and III indicating greater variability in genetic make up of the genotypes included in theseclusters. Based on inter cluster distances, genotypes present in the clusters viz., I, III and IV are advisable to used as parents forhybridization programme to develop heterotic hybrids in maize

Exploitation of natural variability in maize for β - carotene content using HPLC and gene specific markers

Vitamin A deficiency is a major world health problem, affecting up to 127 million pre-school children and 7 millionpregnant women worldwide (West, 2003). Human selection for yellow endosperm has led to diversification of graincarotenoid content and composition. This variation has remained largely untapped in modern breeding programs thathave focused nearly exclusively on yield gains. Maize displays considerable natural variation for carotenoidcomposition, including vitamin A precursors α-carotene, β-carotene, and β -cryptoxanthin. Sixty four maize inbred linesof India were grown and evaluated for whole kernel carotenoids and beta carotene content using high performanceliquid chromatography (HPLC). The lines averaged 14 :g/g for total carotenoids (5.58 to 63.9 :g/g) and 1.69 :g/g for β-carotene (0.122 to 4.74 :g/g). High level of β - carotene was observed in UMI 946, UMI 176, UMI 79, UMI 34 andUMI 12 and these would be used in the breeding programs to enhance the β – carotene contents. Previous study showedfour natural lcyE polymorphisms explained 58% of the variation in these two branches and a threefold difference in provitaminA compounds. In screening for polymorphisms in key haplotypes, four regions were selected and scored acrossthe entire panel of favourable haplotype using SNP and SSR markers. The polymorphs were obtained for all primer usedand the presence of the amplification of for particular marker showed the increase in β - carotene content across theinbreds. Development of LCYE based breeding markers for maize alone will not be effective unless hydroxylation isalso controlled, for non pro vitamin A xanthophylls compounds will predominate. So in our future study, we should beaiming at breeding for high β - carotene in maize by emphasizing on characterization of β - carotene hydroxylase genesfor enhancing the relative levels of seed β - carotene