Implications of correlations and genotype by environment interactions among cotton traits

The existence of negative correlations, coupled with significant genotype x environment interaction (GE) among cotton traits poses both opportunities and challenges in breeding. This study aimed at determining the existence of GE on seed cotton ( Gossypium hirsutum L.) yield, lint yield, earliness index, gin out turn ratio, 100 seed weight, split boll weight and fuzz grade and correlations, among these traits, as well as understanding the implications on variety evaluation and release. Ten genotypes from Cotton Research Institute, Zimbabwe, were evaluated across seven locations, during the 2012/13 and 2013/14 cropping years with three replications at each location. Seed cotton and lint yield, earliness index, gin out turn ratio, 100-seed weight, split boll weight and fuzz grade were measured on the genotypes at all locations. Analysis of variance for GE showed significant differences (P<0.05) on most traits, except earliness index. There were huge GE and error variance components on seed cotton yield and allied traits that reduced heritability and correlation among these traits. Seed cotton and lint yield were significantly correlated (P<0.001; r = 0.95) to each other; while split boll weight had significant correlation (P<0.004; r = 0.82) with 100-seed weight. The genotype plus GE biplot analysis showed that SZ 9523 had high and stable yield and desirable fuzz grade, which made it an ideal genotype for release. All locations belonged to one complex mega-environment with Chisumbanje Research Station more representative and most discriminating location which can be used in early generation testing of cotton.L\u2019existence des corr\ue9lations n\ue9gatives, coupl\ue9e avec l\u2019interaction significative entre g\ue9notype et environnement (GE) parmi les traits de coton pose \ue0 la fois des opportunit\ue9s et des d\ue9fis en s\ue9lection. Cette\ue9tude a pour objectif de d\ue9terminer l\u2019existence de GE sur le rendement des graines de coton ( Gossypium hirsutum L.), le rendement en fibres, l\u2019indice de pr\ue9cocit\ue9, le taux de gin obtenu, le poids de 100 graines, le poids des capsules fendues et la qualit\ue9 du duvetet les corr\ue9lations, entre ces traits, de m\ueame que comprendre les implications sur l\u2019\ue9valuation de la vari\ue9t\ue9 et la d\ue9livrance. Dix g\ue9notypes de l\u2019Institut de Recherche sur le Coton du Zimbabwe, ont \ue9t\ue9 \ue9valu\ue9s dans sept localit\ue9s, durant les ann\ue9es de production 2012/2013 et 2013/2014 avec trois r\ue9plications dans chaque localit\ue9. Le rendement en graine et en fibre, indice de pr\ue9cocit\ue9, le taux de gin obtenu, le poids de 100 graines, le poids des capsules fendues et la qualit\ue9 du duvet ont \ue9t\ue9 mesur\ue9s sur les g\ue9notypes dans toutes les localit\ue9s. L\u2019analyse de variance pour GE a montr\ue9 de diff\ue9rences significatives (P<0,05) sur la plupart des traits, sauf l\u2019indice de pr\ue9cocit\ue9. Il y avait une grande composante de la variance de GE et l\u2019erreur sur le rendement en graine du coton et les traits li\ue9s qui ont r\ue9duit l\u2019h\ue9ritabilit\ue9 et la corr\ue9lation parmi ces traits. Le rendement en graine et en fibre du coton ont \ue9t\ue9 significativement corr\ue9l\ue9s (P<0,001; r = 0,95) l\u2019un \ue0 l\u2019autre\ua0; alors que le poids des capsules fissur\ue9es ont de corr\ue9lation significative (P<0,004; r = 0,82) avec le poids des 100 graines. L\u2019analyse de g\ue9notype plus GE biplot a montr\ue9 que SZ9523 a eu de haute et stable rendement et d\ue9sirable qualit\ue9 du duvet, qui le rend un g\ue9notype id\ue9al pour la d\ue9livrance. Toutes les localit\ue9s ont form\ue9 un complexe m\ue9ga-environnement avec la station de recherche de Chisumbanje plus repr\ue9sentative et plus discriminante qui peut \ueatre utilis\ue9e pour une \ue9valuation du coton \ue0 une g\ue9n\ue9ration pr\ue9coce

Willingness to pay for quality traits and implications for sweetpotato variety breeding: case of Mozambique

Despite decades of research and dissemination of improved sweetpotato varieties, uptake at scale remains low and envisaged development goals of food security and livelihoods remain elusive. This is despite demonstrated impacts of such technologies in combating food and nutrition insecurity, amidst global challenges like climate change. Growing evidence show that end-user acceptance of improved varieties is critical in the widespread adoption of such varieties, and inclusion of the heterogenous preferences of diverse sets of end-users in the variety development process is therefore critical. With global changes in weather and consumption patterns, end-users are now demanding varieties that are more suitable to their unique consumption needs, production environments, new market demands and have desired processing characteristics. Such dynamics in demand have necessitated rethinking of breeding programs from the traditional focus on agronomic gains such as increase in yields and yield protection, to consideration of more nuanced quality-related traits that appeal to targeted populations. Against this background, this study sets out to explore the decision-making behavior of Mozambican sweetpotato producers in variety selection, and the implicit value placed on different sweetpotato traits, including the often ignored but crucial quality traits. The aim of the study is to identify the economic valuation of such traits and how they are traded off in variety selection decisions, to allow for prioritization in breeding efforts. To achieve this, an exploratory sequential design in a predominantly quantitative mixed-method design was adopted for the study. First, based on the insights from a gender disaggregated qualitative assessment among sweetpotato growers and consumers and in consultation with breeding experts from Mozambique, the most preferred sweetpotato variety traits in the regions of study were established. These traits were then utilized in the design of a choice experiment, implemented among 860 sweetpotato producers spread across four sweetpotato growing regions in the country. Finally, a generalized multinomial logit model was used to estimate implicit economic valuation of each of the considered trait, as well as heterogenous valuation of such traits across gender, education and age of respondent groups. Results from the study show that producers have a high preference for quality-related traits, with preference for Vitamin A being higher than that for drought tolerance, while dry matter content is valued about the same as drought tolerance. While scoring significantly lower than Vitamin A, drought tolerance and dry matter content, other quality-related traits like root size and sweet taste also have significant positive values implying their importance in informing sweetpotato variety choice. In terms of gender heterogeneity, flesh color is highly valued among the women sub-sample. The study identifies Vitamin A, dry matter content, sweet taste, and medium to big root size, as the key preferred quality traits in Mozambique, in that order. The results imply that these quality traits should be pursued as a suite in breeding objectives, in combination with essential agronomic traits such as high yields and drought tolerance, for higher acceptance and demand of improved sweetpotato varieties across the country

Improving productivity of orange-fleshed sweetpotato (Ipomoea batatas) through intercropping with legumes and moderate phosphorus application

Sweetpotato yield is adversely affected by poor soil fertility in Mozambique where access to inorganic fertilisers is lacking. The objective of the study was to evaluate the effectiveness of intercropping sweetpotato with groundnut and soybean at various phosphorus (P) fertilisation levels on the productivity of sweetpotato. A field experiment was conducted at Umbeluzi Research Station in southern Mozambique during the 2013/14, 2014/15 and 2015/16 growing seasons. The experimental design was a split plot with seven crop combinations and three P levels (0, 20 and 40 kg P ha(-1)). Phosphorus at 20 and 40 kg ha(-1) produced best total storage yield, total biomass and commercial root yields, whereas P at 40 kg ha(-1) favoured highest vegetative growth. Sweetpotato-groundnut intercropping produced the best commercial root yield and total biomass. Phosphorus applied at 40 kg ha(-1), combined with sweetpotato and groundnut intercropping, produced the highest total and commercial storage root yield but these two parameters were not significantly different from sweetpotato-groundnut intercropping at 20 kg P ha(-1). For farmers growing sweetpotato under similar climatic and soil conditions, we recommend intercropping with ground-nuts and additional application of 20 kg P ha(-1) for farmers with fertiliser access

Yield, nutritional quality and stability of orangefleshed sweetpotato cultivars successively later harvesting periods in Mozambique

Long-term storage of sweetpotato roots is a great challenge for smallholder farmers in Mozambique. Piecemeal harvesting allows several months supply of roots for household consumption provided weevil infestation is avoided. The objectives of the present studies were to determine yield and changes in key macro- and micronutrients associated with early or late harvesting of orange-fleshed sweetpotato cultivars in Mozambique. Four trials representing harvesting periods of 3, 4, 5 or 6 months after planting were established at Gurue in 2015. The randomized complete block design with three replications was laid in each trial. Yield measurements were done in the field and samples were selected and scanned for dry matter, beta-carotene, iron, zinc and carbohydrate using Near Infrared Spectrometry. Collected data were statistically analysed (SAS 1997 software). Yield, dry matter, starch, iron and beta-carotene increased linearly in some cultivars as time to harvest was prolonged. Iron was not affected by harvesting period. Stability of micronutrients such as iron, zinc and beta-carotene is essential when piecemeal harvesting. The study allowed accurate grouping of the cultivars tested into maturity groups for the first time

Survival of sweetpotato (Ipomoea batatas [L] Lam) vines in cultivars subjected to long dry spells after the growing season in Mozambique

Optimisation of sweetpotato production potential is not realized in sub-Saharan Africa where dry spells are common after the growing season. Lack of seed cultivars at the beginning of the rainy season is the challenge and identifying those cultivars with the ability to survive a 4 to 7-month dry spell is an important objective in these regions. To this end, the purpose of the present study was to estimate survival of vines of different cultivars under drought stress. Three harvesting times set as 5, 9 and 11 months after planting were established at Umbeluzi, Nwallate and Gurue in 2015. For each harvesting time, 37 clones were evaluated in a randomized complete block design with two replications. Data collected on yield, vine length and number of sprouts were analysed using SAS 1996. Resisto had long stems but no vines after 9 months at any of the sites. The ability of some clones to reach 9 months and 11 months with few vines at Umbeluzi and Nwallate offer sources of planting material for the subsequent season. Sprouting had broad sense heritability above 50%. Sprouting is known to be an important aspect of cultivar survival. While we show that vine length and thickness could be traits responsible for sweet potato drought tolerance

Access to lowland areas for vine conservation: a key determinant of increased utilization of orange-fleshed sweetpotato in Niassa province, Mozambique

The objective of this study is to evaluate the use of lowland areas for vine conservation to improve the availability and access of planting material during the main planting period and subsequently improve access to Orange Fleshed Sweetpotato (OFSP) roots for consumption and income. The study was implemented in 8 districts in Niassa province in early December 2015, among 271 households (HH), where 77% of these households had children under 5 years and 34% of the respondents were women. These households were selected randomly among households that had received OFSP planting material between 2013 and 2015. Data about vine conservation, use of lowland areas, OFSP consumption and income from OFSP were collected and analyzed using SPSS. Results were compared with the baseline survey results from 2013. Eighty seven percent of households have access to lowland areas. The households using lowland areas for vine conservation increased from 41% in 2013 to 58% in 2015 and the use of small garden plots from 14% to 26%. The households conserving vines in upland fields dropped from 56% in 2013 to 7% in 2015. About 53% of households still planted in June (beyond the main planting season) while 24% continued to plant year around. However, cultivation on small plots dominated from March to December, mainly for vine multiplication. Delvia, Irene and Gloria varieties were mentioned respectively by 43 %, 21 % and 20 % of households as their preferred varieties. All households consumed OFSP roots. However, more than 50% of households consumed OFSP from April to October. Fifty six percent of households sold OFSP roots which generated an average income of 48 USD per household per year. The use of lowland areas for vine conservation has increased and vine management has improved. Consequently, production area has increased by 23%, root yield has increased by more than 100%, from 6.0 t/ ha as average national yield to 15.5 t/ha, average yield for the survey, and the period of consumption from own production has also increased to seven months. Awareness campaigns will continue to promote year round production of OFSP

Adaptation to mid-season drought in a sweetpotato (Ipomoea batatas [L.] Lam) germplasm collection grown in Mozambique

Drought has negative effects on sweetpotato production. Two experiments with two watering treatments (irrigated and water-stressed) were conducted at Umbeluzi Research Station in 2015. The objectives were to (i) determine response of 48 sweetpotato germplasms to mid-season drought, (ii) determine best traits for improvement of storage root yield under mid-season drought and (iii) assess the selection criteria for identifying drought tolerance in sweetpotato germplasms. The irrigated and water- stressed trials received 640 and 400 mm of water, respectively, throughout the season. Water stress was imposed from 30 to 70 days after planting. Each treatment had two replicates arranged in a randomized complete block design. Data collected on storage root and vine yield and derived drought tolerance indices including harvest index were subjected to analysis of variance in R. Sweetpotato germplasms with high storage root yield under mid-season drought were associated with a high harvest index. Harvest index stability and the geometric mean are key to identifying cultivars with high and stable storage root yield under both treatments. MUSGP0646-126, Irene and Ivone combined both low TOL, SSI, HI and high yield storage root yield across the treatments and over seasons. The use of drought and harvest indices is encouraged for selecting improved cultivars for varied production environments and their regular use in accelerated breeding schemes is suggested

Effect of period of cultivation on the abundance and distribution of weed seeds in the soil profile

An experiment was laid down in the greenhouse to determine the distribution of weed seeds at different soil depths and period of cultivation on the distribution of weed seed bank in the soil profile in Muzarabani. Soil samples from different depth levels (0-10, 10.1-20, 20.1-30 cm) were collected soon after harvesting from three different sites namely Gutsa, Mufudzi and Muringazuva of Muzarabani district. The soil samples were put in trays in the greenhouse and watered after every two days to field capacity. Weed seedlings were identified, counted, recorded and discarded for a period of 3 months. Soil samples were disturbed every week to allow more germination of dormant weeds. Depth (P=0.000) and site (P=0.005) had highly significant effects on the total number of weeds that emerged from the soil samples. The 0-10 cm of the soil had the highest weed seedlings that emerged. There was an equal weed seed distribution in the 10-20 cm and the 20-30 cm of the soil. Gutsa had the largest seed bank and there was no significant difference in seed bank size between Mufudzi and Muringazuva. Some weed species were site specific, Senna obtusifolia was only found in Muringazuva and absent in other sites. Eleusine indica was found in Mufudzi and was absent in other sites