Identification of quantitative trait loci associated with iron deficiency chlorosis resistance in groundnut (Arachis hypogaea)

Iron deficiency chlorosis is an important abiotic stress affecting groundnut production worldwide in calcareous and alkaline soils with a pH of 7.5–8.5. To identify genomic regions controlling iron deficiency chlorosis resistance in groundnut, the recombinant inbred line population from the cross TAG 24 × ICGV 86031 was evaluated for associated traits like visual chlorosis rating and SPAD chlorophyll meter reading across three crop growth stages for two consecutive years. Thirty-two QTLs were identified for visual chlorosis rating (3.9%–31.8% phenotypic variance explained [PVE]) and SPAD chlorophyll meter reading [3.8%–11% PVE] across three stages over 2 years. This is the first report of identification of QTLs for iron deficiency chlorosis resistance-associated traits in groundnut. Three major QTLs (>10% PVE) were identified at severe stage, while majority of other QTLs were having small effects. Interestingly, two major QTLs for visual chlorosis rating at 60 days (2013) and 90 days (2014) were located at same position on LG AhXIII. The identified QTLs/markers after validation across diverse genetic material could be used in genomics-assisted breeding.     

安顺市龙宫景区旅游环境容量研究

对安顺市龙宫景区旅游环境容量进行测算,结果表明：龙宫景区旅游经济环境容量、旅游生态环境容量、旅游空间环境容量分别为57 879人次/d、47 174人次/d、10 502人次/d.而据调研数据得知,龙宫黄金周期间的游客接待量约为43 887人次/d,远远超出景区的空间环境容量,同时不断接近生态环境容量.基于此,提出促进龙宫景区可持续发展的相关可能性对策.     

Oil and protein quality of groundnut mutants

Variability in oil quality was observed in four groundnut mutants (TG-1, TG-3, TG-14, TG-16) induced by -irradiation. The fatty acid composition of the mutants differed from their parent Spanish Improved. All the mutants had lower linoleic and higher oleic acid than the parent Spanish Improved. TG-3 and TG-14 had substantially higher linoleic acid and lower oleic acid as compared with TG-1 and TG-16. Other fatty acids also showed minor variation amongst mutants and Spanish Improved. The ratio of oleic to linoleic acid, which is an index of oil stability, was 2.7 and 3.3 fold respectively in TG-16 and TG-1 as compared with Spanish Improved.Protein percent in TG-1, TG-14 and TG-16 was higher than in Spanish Improved. Amino acid analysis of protein from mutants indicated decreases in methionine and cystine and an increase in tryptophan as compared with Spanish Improved. Other amino acids did not show any major variation between the mutants and Spanish Improved. In all varieties except TG-16, lysine was the first limiting amino acid; threonine was second limiting in all mutants. The essential amino acid content per kernel was higher in mutants than in Spanish Improved.     

Growth Rate,Apparent Nutrient Digestibility and Some Blood Metabolites of Gwembe Valley Goats on Rations Based on Crop Residues in the Hot Dry Season in Zambia

Twelve Gwembe goats (9 females and 3 males; 12–18-months old; average body weight 18.50±0.05 kg) were divided into three groups and fed complete rations based on crop residues. Three residues of oilseeds – bambara groundnut shell (BGS), groundnut shell (GNS) and sunflower head (SFH) – were used. The rations were isonitrogenous and isocaloric. The average daily dry matter intake was BGS 0.85±0.02, GNS 0.88±0.02 and SFH 0.89±0.03 kg/head per day, which did not differ from each other significantly (p>0.05). However, the daily live weight gains were significantly different (p<0.05). Goats that consumed SFH gained more (84 g; p<0.05) in live weight than those fed BGS (76 g) or GNS (72 g). Feed conversion followed the pattern of live weight gain. The plasma non-protein N values were 25.1±0.36, 24.6±0.38 and 24.9±0.35 mg/100 ml, while the plasma glucose concentrations were 67.2±1.44, 65.1±1.32 and 67.8±1.49 mg/100 ml, respectively, for goats on BGS, GNS and SFH rations, with no significant difference (p>0.05) between the three rations. The cost/kilogram for each of the rations were all within the same range, but the cost/kilogram of live weight gain was lower for the SFH ration than for the GNS and BGS rations. The nutrient digestibilities of the crop residues were similar among the treatments. Overall, SFH tended to perform better than GNS or BGS in these complete rations for goats in the hot dry season.     

龙桑曲枝性遗传的再研究

龙桑是桑树的一个栽培品种,它的最大特点是具有曲枝性,本文对龙桑曲枝性遗传作了进一步的研究。研究结果表明,用龙桑嫁接苗天然授粉的种子培育的具有曲枝性状的龙桑实生苗,相互传粉所获得的种子再培育的实生苗,其中有75％的幼苗表现为曲枝性,25％的幼苗表现为直枝性。进一步证明了,龙桑曲枝性遗传机制符合一对显隐性基因的分离和自由组合规律。     

高产抗青枯病花生新品种泉花10号的选育研究

泉花10号系我所用广A为母本，粤油92为父本杂交选育而成花生新品种，具有高产、稳产、抗青枯病、适应广、优质等特点。另外，该品种还表现出开花集中、结荚性好、叶面积指数(LAI)较大、净同化率(NAR)高、干物质积累多、分配系数大、库大、源大、库源协调等高产花生的生育特性。     

Evaluation of Groundnut Genotypes for Tolerance to Phosphorus Deficiency

Phosphorous (P) is one of the most deficient nutrients owing to its fixation and low mobility in acid soils. A total of 324 genotypes were screened in both P sufficient and insufficient conditions to evaluate the P uptake efficiency. Thirty-four responsive genotypes were evaluated in solution culture with two checks, ICGV 86590 and JL 24. The components of variability revealed high magnitude and highly heritable nature of the variation. Highly responsive genotypes to P insufficiency; ICG 14475, ICGV 92188, and M 68 were further tested for phosphorus uptake efficiency at 15, 30, and 45 days after sowing (DAS) along with checks in sand culture in pots. ICG 14475, ICGV 92188, and ICGV 86590 were found superior in both acquisition and utilization of phosphorus due to enhanced root production for P exploration and shoot expansion, respectively. JL 24 was poor in acquisition due to lack of response in root traits under P insufficiency.     

Genetics of nonnodulation in groundnut (Arachis hypogaea L.). Studies with single and mixed Rhizobium strains

Summary Genetic studies of nonnodulation in groundnut were carried out in a cross, NC 17×PI 259747, with a single Rhizobium strain, NC 92, and a native Rhizobium population.The normal nodulation of the parents, F₁ generations and backcross progenies, and the F₂ segregation for nodulation and nonnodulation confirmed that nonnodulation in groundnut is controlled by two duplicate recessive genes.Approved ICRISAT Journal Article No. 211.     

Growth and development of bambara groundnut (Vigna subterranea) in response to soil moisture: 1. Dry matter and yield

The effect of drought on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled-environment glasshouses in the UK. There were three landraces (S19-3, DipC and UN from Namibia, Botswana and Swaziland, respectively) and two watering regimes; a control that was irrigated weekly to 90% field capacity and a drought treatment with no irrigation from 49 days after sowing (DAS) until final harvest (147 DAS). Bambara groundnut responded to drought by reducing the rate of leaf area expansion, final canopy size and total dry matter (TDM) during vegetative growth. Drought also caused significant reductions in pod dry matter (PDM), pod number, seed weight and harvest index (HI), leading to a decrease in final pod yield that was different between landraces. Across landraces, drought reduced mean pod yield from 298 g m⁻² to 165 g m⁻², representing 45% yield loss. Despite the reduction in all landraces, the mean pod yield across the droughted treatments that had received no water for almost 100 days indicated the resilience of the species to drought. The three landraces differed in their phenology; S19-3 exhibited a reduced phenology while UN maintained the longest life cycle. The different responses of the landraces reflect their adaptation to their local climates where mean annual rainfall ranges between 365 mm (Namibia) and 1390 mm (Swaziland). We discuss the significance of these results for future breeding programmes on bambara groundnut.     

Mechanisms of Resistance to Tobacco Cutworm (Spodoptera litura F.) and their Implications to Screening for Resistance in Groundnut

Summary The Tobacco cut worm (Spodoptera litura Fab.), a polyphagous defoliating insect is a major pest on groundnut in Asia. Screening germplasm for resistance to Spodoptera litura in the field under high infestation revealed significant genotypic variation. Low damage was observed on Mutant (28-2), NC Ac 343, ICGV 86031, R 9227 and TAG 24. In the laboratory rearing of insect, the resistant genotypes, NC Ac 343, Mutant 28-2 and R 9227 affected larval growth and survival, pupal development, adult emergence and fecundity indicating antibiosis as the principal mechanism of resistance. The reduction in larval weight reared on ICGV 86031 could be due to the toughness of leaves. Though the genotype TAG 24 suffered low damage in the field, the larval and pupal development was normal in the laboratory revealing avoidance/non-preference as the mechanism of resistance. Based on the insight gained from the growth and development of the insect on resistant genotypes, the gain in weight (GIW) of the pre-starved larvae was assessed for its suitability in rapid screening. GIW in 24 h by III instar larvae fed with fully expanded II leaf was found suitable in screening for resistance based on antibiosis. The method could be adopted for screening large breeding populations in a short time under laboratory conditions. The resistant genotypes with different mechanisms of resistance could be hybridized to pool the resistant genes for enhancing the level and effectiveness of resistance in the management of the pest.