Cowpea sown after wetland rice in tropical monsoon climates is frequently subjected to soil saturation and a high water table during early growth. We compared the effects of variation in water table regime on the shoot and root growth, and plant water relations of two medium-maturing (cv. TVX3236-01G and TVX3410-02J) and two early maturing (cv. BS6 and IT82D-889) cowpea [Vigna unquiculata (L.) Walp] cultivars in three water table depth regimes on a Typic Tropudalf toposequence. Our objective was to elucidate the possible mechanisms of differential cultivar adaptation to shallow water table conditions. The shallow water table regime (SWT) significantly reduced the total dry matter accumulation and harvest index for BS6, an early maturing cultivar (reductions in stems, leaves, pods, and total dry matter by 82, 77, 88, and 84% respectively), while the least reductions (reductions by 44, 3, 57 and 55%, respectively) was observed for TVX 3410-02J, a medium-maturing cultivar. Roots of the medium cultivars were more concentrated in the top 0.2m in the SWT Site than those of the early-maturing cultivars. Roots of the medium cultivars later penetrated to 0.8-m maximum depth compared to 0.6-m maximum depth for the early cultivars, and extracted soil water from 20 cm deeper in the soil profile than the early maturing cultivars. The medium-maturity cultivars maintained higher leaf water potentials and lower canopy temperatures throughout the season. This was associated with greater end-of-season total soil profile water extraction. The medium-maturing cultivars showed better adaptation to shallow water table conditions due to superior plant water status, rooting pattern, and biomass production and partitioning.
Tag: cultivars
Water table gradient effects on the performance of diverse cowpea cultivars
Cowpea sown in tropical monsoon climates is often constrained by soil saturation and a high water table during growth. We hypothesized that a strong interaction exists between cowpea maturity class and the soil water table depth regime experienced during the growing season, and that the occurrence of shallow water table depths in the dry-wet transition period before rice and the rapid decline in water table depth in the wet-dry post-rice period favor early maturing cultlvars. The effects of three water table regimes on the performance of 24 diverse cowpea [Vigna unguiculat (L.) Walp] cultivars was studied on a Typic Tropudalf toposequence. The water table depths in the shallow (SWT), medium (MWT), and deep (DWT) water table regimes varied between 0.06 to 0.54 m, 0.28 to 0.96 m, and 0.68 to 1.44 m in the 2 yr of dry season (DS) experiments. In the wet season fWS), the three regimes were 0 to 0.27 m, 0.30 to 0.60 m, and 0.55 to 1.05 m. Most of the early maturing cultivars exhibited their best performance in the DWT regime, but the medium maturing cultivars were superior in seed yields in all water table regimes. The mean yields of the early maturing cultivars were reduced by 49% (1986–1987 DS) and 57% (1987–1988 DS) in SWT compared to DWT. They were reduced by 50% in the 1987 wet season. The mean yield reductions for the medium maturing cultivars were 40%, 54%, and 51%, respectively, in SWT compared to DWT. Pods per plant was the yield component most affected by excess moisture. Flowering in the SWT was delayed by 4 vs 5 d (DS) and 5 vs 7 d (WS) between the early and medium maturing cultivar groups, respectively. The superiority of the medium maturing cultivats was consistent among sites with a water table within the root zone for a major portion of the crop season.
Performance of pistachio (Pistacia vera L.) in warming Mediterranean orchards
Woody perennial species from temperate regions fall dormant during the cold winter season to avoid unfavourable conditions. To break out of dormancy and eventually flower, they must fulfil cultivar-specific chilling and heat requirements. Phenology analysis can clarify the climatic requirements of tree cultivars and thus provide critical information to ensure the future viability of orchards in warm growing regions, where warmer winters are expected as a result of climate change. We used Partial Least Squares (PLS) regression to correlate first bloom dates of 4 local and 3 foreign pistachio (Pistacia vera L.) cultivars with daily chill and heat accumulation (quantified with the Dynamic Model and Growing Degree Hours Model, respectively) for 18-year records (1997–2016) from Sfax, Tunisia. PLS outputs allowed delineation of the chilling phase, during which high chill accumulation was correlated to early bloom, and the forcing phase, when this was true for high heat accumulation. Both phases showed discontinuities. During September and October, high heat accumulation appeared to first have a bloom-delaying effect, followed by a bloom-advancing effect, indicating that temperature during dormancy induction may affect bloom dates. Chilling requirements were estimated between 32.1 ± 2.3 and 33.3 ± 2.2 Chill Portions and heat requirements between 9974 ± 198 and 12,738 ± 235 Growing Degree Hours. This study revealed limitations of the Dynamic Model, which is often considered the most accurate among commonly used models, in the warm Tunisian climate. High temperatures during the chilling phase had a significant bloom-delaying effect on all pistachio cultivars. Low chill accumulation was related to very low yields and associated with zero production in 1995, 2001 and 2007. Low flowering percentage, high bud fall percentage, long and inhomogeneous bloom, and co-occurrence of several phenological stages on the same branch were symptoms of lack of chill in 2016.
Effect of organic fertilizer on the growth and fruit yield of six paprika (Capsicum annum L.) cultivars in Malawi
The production of paprika (Capsicum annum L.) under small-scale farm conditions in southern Africa is constrained by low soil fertility and lack of appropriate cultivars. The objective of this study was to determine the growth responses and fruit yields of six cultivars of paprika to organic and inorganic nutrient sources. The study was conducted in 2007 and 2008 at Chitedze Agricultural Research Station in Malawi. A combination of six paprika cultivars and four nutrient sources, namely (1) organic input from Gliricidia, (Gliricidia sepium) biomass, (2) inorganic fertilizer, (3) integrated nutrient input (Gliricidia biomass + inorganic fertilizer), and (4) control (no nutrient input) were compared. Each combination was replicated five times. A split-plot design was used where nutrient sources formed the main plot and cultivars the sub-plots. Plant height differed due to nutrient source in 2007 and 2008, while differences due to cultivar were minor. The control plots produced the shortest plants (height 60 cm). Numbers of branches and fruits per plant differed due to nutrient source and cultivar during most of the study period. Plants receiving either organic inputs (Gliricidia biomass) alone or the integrated nutrient input alone had significantly higher stem, leaf and fruit weight compared with the control. Average fruit yield was lower in control plots than in plots receiving the organic input alone or the integrated nutrient input. Among cultivars, Papri-King, Papri-Supreme and Papri-Queen produced higher dry fruit yield. The ASTA and RAL colour rating was within the internationally accepted range for fruit from the treatments.
Chilling and heat requirements for local and foreign almond (Prunus dulcis Mill.) cultivars in a warm Mediterranean location based on 30 years of phenology records
Most temperate fruit and nut trees require fulfillment of chilling and heat requirements during their dormant phase in order to flower regularly and produce economically satisfying yields. Recent and expected temperature increases are cause for concern for many orchard managers, especially in warm growing regions, because they may compromise the trees’ ability to fulfill their climatic needs. To explore temperature responses across different cultivars, we applied Partial Least Squares (PLS) regression to correlate bloom dates of 12 local and 25 foreign almond (Prunus dulcis Mill.) cultivars in Sfax, Tunisia with daily chill and heat accumulation based on more than 30 years of phenology records from 1981 to 2014 and long-term daily minimum and maximum temperatures between 1973 and 2016. We used three chilling models (the Chilling Hours, Utah and Dynamic Models) and one forcing model (Growing Degree Hours; GDH) to quantify climatic needs. Chilling and forcing phases derived from the PLS outputs appeared discontinuous for all almond cultivars and were shorter for the local almond cultivars than for the foreign cultivars. The Dynamic Model provided the most precise estimates of chilling requirements but still appeared to have some shortcomings. According to the Chilling Hours Model, chilling needs were very low, but still higher than for the Utah Model, where the negative chill contributions by high temperatures implied negative chilling requirements. The Chilling Hours and Utah Models therefore do not seem suitable for the climate of the Sfax region. For local almond cultivars, chilling requirements were estimated at between 3.4 and 15.5 Chill Portions (CP) and heat needs between 3962 and 8873 GDH. For foreign cultivars, chilling requirements varied from 6.7 to 22.6 CP and heat needs from 2894 to 10,504 GDH. High temperatures during the chilling phase showed a significant bloom-delaying effect on most of the local and the foreign almond cultivars.
Market analysis of selected agroforestry products in the Vision for Change Project intervention zone, Côte d’Ivoire
Cocoa yield per hectare in Côte d`Ivoire is among the lowest in the world, ranging from 0.2 to 0.5 tons/ha per year. This figure continues to decline each season due to decreased soil fertility, increased disease pressure, the aging of cocoa orchards, and low use of inputs (Assiri et al. 2012, FLA 2012). Yields could be increased if farmers were able to apply fertilizer in recommended quantities, replant old orchards (especially with improved cocoa varieties), and control diseases with f ungicides and other methods. However, for various reasons such as lack of financial means, low levels of technical training and reduced incentives to invest in cocoa because of low prices, the majority of Ivorian cocoa farmers are not implementing these so il and crop improvement management methods (Nkamleau et al. 2007, FLA 2012). In view of this , Mars I ncorporated , in col labo r ation with the Ivorian Government , embarked on the Vision for Change (V4C) project as a means of addressing the problem of low prod uctivity of cocoa. This project is being implemented by the World Agroforestry Centre (ICRAF) . The initiative is currently setting up a network of Cocoa Development Centre s (CDCs) throughout the region of Soubré, the most productive cocoa region in Côte d` Ivoire, and conducting on – farm research into different cocoa cultivars, rehabilitation of old orchards by grafting, and the effect of fertilizer application and other management practices ( ICRAF 2012 ) . In future the project will enter the extension stage, and the best methods of increasing cocoa yields, plus affordable inputs to accomplish them, will be made accessible to farmers throughout the region. This initiative is designed on the same model as a successful project initiated in Indonesia by Mars in 20 03, which increased cocoa yields from 0.5 to 2.5 tons/ha per year, on average (Pye – Smith 2011). Initial studies of the effects of rehabilitation methods in field trials in Côte d’Ivoire are encouraging, showing an 83% average increase in yields and an aver age profitability rate of 377% (Assiri et al. 2012).
Effect of elevation on photosynthesis of young mango (Mangifera indica L.) trees
Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars.