Mean Tuber Weight Research Articles

The effect of density on tuber yield in plants grown from true potato seed in seed beds during two contrasting seasons

The production of potatoes from true seed was studied in direct-sown seed beds during both winter and summer seasons in Lima, Peru. After emergence, seedlings were thinned to give 6, 12, 24, 48 or 96 plants per m2. In all five density treatments plants were arranged in a square configuration. In both seasons, increasing plant density significantly increased total tuber number as well as tuber weights in the grades 1–5 g, 5–20 g and 20–40 g. The yield of tubers larger than 40 g was similar in all densities. In the warm summer season, tuber number was significantly reduced and mean tuber weight was 56% greater compared with that in the winter season. The potential of producing consumer potatoes from true seed in seed beds in warm climates is discussed.

Influence of nitrogen and potassium fertilizer on growth of sweet potato (Ipomoea batatas) in Papua New Guinea

Abstract Two factorial fertilizer trials involving four levels of nitrogen and four levels of potassium were carried out on sweet potato to gain a better understanding of the way in which fertilizer influences growth and yield. The trials were done on a Vitrandept soil at Keravat which has a wet lowland tropical climate. The general pattern of crop development and yield responses is described, using the growth analysis technique. Under conditions of continuous cropping, nitrogen (N) had a greater influence on growth and yield than did potassium (K). N fertilization up to a rate of 225 kg N ha−1 increased tuber yield, mean tuber weight, total plant dry weight, dry weight of all plant components, leaf area index, leaf area duration, number of leaves per plant, mean leaf area per leaf, crop growth rate; and, for some periods, leaf area ratio (LAR) and relative growth rate. N reduced number of tubers per plant early in the crop. K fertilization up to a rate of 375 kg K ha−1 increased tuber yield, number of tubers per plant, mean tuber weight, total plant dry weight, mean leaf area per leaf and harvest index. It reduced the percentage dry weight of tubers and LAR in Trial 2. It is suggested that N influenced yield by increasing leaf area duration which in turn increased mean tuber weight and hence tuber yield. K influenced tuber yield via an increase in the proportion of dry matter diverted to the tubers and a rise in tuber number per plant. The effect of K occurred by 7 weeks after planting and it is suggested that K fertilizer be applied early in the crop life.

Relationships of defined PVX infection levels to verticillium wilt, yield, and quality of the Russet Burbank potato

Field studies were conducted over a three-year period to investigate effects of potato virus X (PVX) on the Russet Burbank potato cultivar. Seed (PVX-free and PVX-infected) used for this three-year study originated from the same PVX-free source and was grown and stored under similar conditions. PVX-free seed was found to increase yield over PVX-infected plots by 9 to 32%. With these yield benefits, effects of PVX on either the incidence of verticillium wilt or plant nutrition were not significant. There was a trend (P = 0.10) for a reduction of mean tuber weight when the PVX infection level exceeded 19%. Because of increases of undersized potatoes, the yields of U.S. #1 potatoes were reduced as levels of PVX infection were increased. With a PVX infection level of 36%, the yield of U.S. #1 tubers was reduced by 21% when compared with plots having 0% PVX. At an 88% infection level, the yield of U.S. #l’s was reduced still further (36% lower than plots with 0% PVX). Results demonstrate the importance of the level of PVX infection to potato production.

Comparisons of rate of photosynthesis and tuber yield of a dihaploid, its chromosome-doubled derivatives and parent

The rates of photosynthesis per unit leaf area and tuber yields of a dihaploid of cv. Pentland Crown and its chromosome-doubled derivatives were similar. Pentland Crown had a higher rate of photosynthesis and higher yield than the dihaploid and its tetraploid derivatives. This was shown by a larger number of tubers per plant and higher mean tuber weight for the cultivar. Fresh and dry weight shoot yields of the dihaploid, its chromosome-doubled derivatives and parent were not significantly different from each other (P>0.05). The higher yield of Pentland Crown was possibly due to a higher rate of photosynthesis.

Título en español

Pedazos de 115 g de ñame Habanero (Dioscorea rotundata Poir) de alta calidad se trataron par una hora con fungicidas, 48 horas antes de sembrarlos para determinar el efecto sobre el brote y el rendimiento. Se escogió un predio experimental que no había estado sembrado de ñames previamente y estaba libre de nematodos parásitos del ñame. Se registró, 91 , 95 y 96% de brote en los pedazos tratados con captan + benomyl, captan, y captan + thiabendazole, respectivamente, comparado con 52% en los que no se trataron con fungicida (testigo). El brote temprano (5 semanas después de la siembra) fue mayor en los pedazos tratados con captan + thiabendazole (24%) que en los tratados con captan + benomyl (1%), con captan (2%) o el testigo (1%). A las 9 semanas, los tratamientos con fungicidas no fueron diferentes significativamente en el porcentaje de pedazos que brotaron (91-96%). Se determinaron correlaciones positivas entre el porcentaje de pedazos que brotaron y el rendimiento (r = 0.77**); el número total de tubérculos cosechados (r = 0.84**) y el peso medio de los tubérculos (r = 0.74**). El testigo produjo más tubérculos por planta (1.64) que los tratados con fungicidas (1.16-1.20). Las pérdidas en el rendimiento del testigo (48%) estuvieron asociadas con las pérdidas en el peso por tubérculo (37%) y con el total producido por área (20%). Se registró un mayor rendimiento tanto por planta como por área y por tubérculo en los que se trataron con captan + thiabendazole que con captan o captan + benomyl. Los factores que determinan la producción total y el tamaño de los tubérculos son el brote más temprano y el brote de un número mayor de pedazos. En este estudio aún cuando se seleccionaron tubérculos de alta calidad y se sembraron en condiciones óptimas, el brote y el rendimiento se redujo casi a la mitad cuando los pedazos no se trataron con un fungicida antes de sembrarlos.

Field trials of foliar sprays of 3,5-dichlorophenoxyacetic acid (3,5-D) against common scab on potatoes

Foliar sprays of 3,5-dichlorophenoxyacetic acid (3,5-D) in June or early July decreased the incidence of common scab by about 30% in four field trials on cv. Maris Piper and cv. Desiree; however, significant decreases in yield and in mean tuber weight were also common.

Yield and combining abilities in Andigena potatoes after six cycles of recurrent phenotypic selection for adaptation to long day conditions

Changes in yielding ability were studied in a population of Andigena which had been subjected to six cycles of selection. Significant increases were detected for percent tuberization, mean yield per hill, mean tuber weight, and average rating for tuber appearance. The earliest improvement in yield was largely the result of improving percentage of tuberization. Later gains came from improving mean tuber weight as well as continued improvement in percentage of tuberization. The largest improvement was observed during the last cycle of selection.

Influence of Liming and Soil pH on Cassava (manihot esculenta) in Tropical Oligotrophic Peat

SUMMARYIn three field experiments studying the liming needs of cassava on peat, optimum tuber DM was obtained at pH 3.8 and optimum top DM at pH 4.2; liming to higher pH values decreased tuber DM while maintaining top DM. Consequently, the Harvest Index decreased over the whole range of soil pH studied (3.49–5.50). Increases in tuber DM per hectare with liming, and with an increasing growth period, were associated with mean tuber weight (r = 0.86) and with Harvest Index (r = 0.65) rather than with tuber number (r = 0.37).

Analysis of Genotype‐Environment Interactions of Potato Yield1

Three methods were used to study genotype‐environment (GE) interactions of potato (Solanum tuberosum L.) yield. They were chosen to represent single (stability variance σ1 of Shukla, 1972), two (genotypic stability parameters α, λ of Tai, 1971), and three (genotypic components v1, v2 and v3 of Tai, 1975) parameters of measurement of genotypic contributions to the GE interactions. Data of marketable yield (W) and three yield components: number of stems/plot (X), number of tubers/stem (Y), and mean tuber weight (Z) of 30 genotypes were collected from nine trials in New Brunswick. Significant differences were found for σ2, α, and λ among the genotypes. The estimates of σ2 were highly correlated to those of λ. Both parameters showed a curvilinear relationship with v1 and v2 suggesting low σ2 and λ values were due to moderate genotypic responses to the environmental components (r1 and r2) supporting X and Y. The linear response parameter α showed close association with v3 which measured the genotypic response to the environmental component (r3) supporting Z. The estimates of v3 showed a moderately positive correlation with the mean marketable yield (W) and were larger than those of v1 and v2 for most genotypes. The estimates of r3 were larger and more variable than those of r1 and r2 over the environments. It is thus concluded that difficulty would be encountered locating high yielding genotypes without sensitive responses to the variation of r3.

Heterosis and Variation of Yield Components in F1 Hybrids Between Group Tuberosum and Group Andigena Potatoes1

Five clones of Solanum tuberosum L. Group Tuberosum (T) and five long‐day adapted clones of Group Andigena (A) were crossed to produce four populations (TT, AA, TA and AT) in such a way that there was selling in the intra‐Group crosses. The populations were grown for 2 years as spaced plants in a randomized, complete‐block design and compared for plant vigor, maturity, tuber number, mean tuber weight, and total yield to evaluate the potential of the inter‐Group hybrid (TA and AT) populations in broadening the genetic base of potato cultivar development. In four comparisons, the TA and AT populations outyielded the TT population by 8.6 to 32.9%. Also, the TA and AT populations generally had larger variance estimates for total yield. It is concluded from the analysis of population means for tuber number, mean tuber weight, and total yield that in the TA and AT populations the heterosis for total yield results largely from the multiplicative interaction of the two yield components. The TA and AT populations showed no consistent reciprocal differences. The TA and AT populations showed greater stability than the TT population. These results have important implications for potato breeding.

Genetic analysis of several traits in potatoes by means of a diallel cross

SUMMARYGenetic variation for nine traits of importance in potatoes was analysed in a half‐diallel set of crosses with six parents. General combining ability (GCA) effects were responsible for differences in maturity. For the other traits (yield, number of tubers, mean tuber weight, percentages of cracked and diseased tubers, texture and blackening following cooking and specific gravity) special combining ability (SCA) was important. The correlations between the traits were calculated. The implication for breeding is that trial crossing would be necessary to identify progenies with good potential. The analyses revealed associations between traits which are potentially useful to the breeder.

Yield and Yield Components of Six Sweet Potato (Ipomoea batatas) Cultivars I. Contribution of Yield Components to Tuber Yield

SUMMARYTotal yield and yield components (tuber numbers and mean tuber weights) of six local sweet potato cultivars were compared in wet and dry season crops. There were significant negative correlations between tuber number and mean tuber weight in five of the six cultivars, and positive correlations between these yield components and total yield, suggesting that cultivars may be grouped into ‘tuber number-tuber weight’ and ‘tuber weight’ types, as well as a ‘random type’ in which yield is related to neither component. Marketable yield tended to be directly related to both components, and cultivars with lower tuber numbers usually produced a higher percentage of marketable yields. The significance of these findings for sweet potato yield improvement is discussed.

Comparative Analysis of Tuber Development in Six Sweet Potato (Ipomoea batatas (L.) Lam) Cultivars

Interrelationships between tuber dimensions and yield during development of six sweet potato cultivars with different tuber shapes were examined. Maximum tuber lengths and tuber stalk lengths were attained after 16 and 8 weeks of growth, respectively. Rates of increase in tuber width in the 16- to 24-week period and final tuber widths were related to the mean tuber weight and yield of the cultivars studied, e.g. rates were highest in the high yielding cv. O49 and low in cv. A16/15. Relationships between parameters of tuber development, tuber dimensions, sink strength and yield were evaluated and tuber width appeared to be the most important single dimensional determinant of high yield. However, tuber shape in cv. 03/62 was different from other cultivars and this cultivar was an exception in the interrelationships described. Some factors known to affect tuber shape and development were discussed.

Productivity of vegetable crops in a region of high solar input. II. Yields and efficiencies of water use and energy

Details are given of final yields and size gradings of three potato crops grown under conditions of high solar input and high temperatures in the Murrumbidgee Irrigation Areas of New South Wales. Total yields were up to 50 t ha-l. Differences resulting from different irrigation treatments were surprisingly small, although mean tuber weight was slightly less in the drier treatments. Water use was about 300 g for each 1 g dry weight produced, and efficiency was slightly greater in the wetter irrigation treatments. Reductions of 21 %and 34 % of the total solar input, using shade covers, markedly reduced yields, and there was no statistical interaction with irrigation treatment. Tuber numbers also decreased with decreasing solar input, though not as much as yields, and mean tuber size was greatest on unshaded plots, least under 34% shade. Tuber moisture percentage at harvest was not affected by the different irrigation treatments, but was reduced in two experiments as shading increased. There were only small differences in plant and stem numbers per unit area between any of the treatments, though stem numbers decreased significantly as shading increased. High crop growth rates were achieved especially during the tuber bulking periods, when up to 22.8 g m-2 day-1 of dry matter were produced in each of two experiments, achieved with conversion efficiencies of photosynthetically active radiation of 3.5 % (spring-planted crop) or 6.1 % (summer-planted crop). The results are in agreement with the hypothesis that assimilation in the potato depends primarily on the 'sink' strength of the developing tubers, which is determined in the 2 or 3 weeks following the onset of initiation. The main effects of differences in solar input appear to be determined in this period. It is suggested that a practical approach to increasing yields in this region may be to increase the numbers of tubers which develop per unit area by increasing plant density and encouraging early haulm growth.

The effects of seed size and spacing on growth and yield of lesser yam (Dioscorea esculenta)

SUMMARYThe effects of seed size and spacing on growth, development and yield of lesser yam and the relationship between growth, development and yield in this yam variety were investigated in the 1967 and 1968 growing seasons. Larger seeds outyielded smaller ones both in the total and ware tuber yields. The seed size effect was associated with a difference in tuber number, leaf area duration and bulking rate. Mean tuber weight at harvest, decreased with the decrease in seed size. Total and ware tuber yields increased with the decrease in spacing distance. The spacing effect was associated with differences in leaf area duration and bulking rate per unit area. Final total dry matter produced per plant increased with the increase in both seed size and spacing distance but the dry matter produced per unit area decreased with the increase in spacing distance. Leaf area index and leaf area duration increased with an increase in seed size and decreased with increase in spacing distance. There was a greater positive relationship between total tuber yield and leaf area duration between tuber initiation and the final sampling period than that between it and absolute leaf area duration.

Effects of nitrogen on yield and chlorophyll of potato (<i>Solanum tuberosum</i> L.) cultivars

Effects of nitrogen on the leaf chlorophyll (chl), yield and yield attributing characters of potato as tuber number and mean tuber weight were studied. Correlation coefficients between the investigated characters were determined. Five nitrogen rates (0, 150, 200, 250 and 300 kg/ha) and four potato cultivars (Burren, Slaney, Anna and Emma) were used in the study. First, second, third class tuber yields and total tuber yield, tuber number per plant, and leaf chl were significantly influenced by both nitrogen rate and cultivar, whereas mean tuber weight was affected only by cultivar. Maximum total yield was obtained at 200 kg N/ha. There was significant linear relationship between leaf chl and N applied (R2=0.91). There were significant correlations between chl and yield and yield related characters. Total yield significantly correlated with leaf chl. Correlations between first class yield and total yield as well as total yield and tuber number per plant were highly significant. Key words: Potato; Solanum tuberosum L.; Leaf chlorophyll; Nitrogen; Yield DOI: 10.3329/bjb.v38i2.5141 Bangladesh J. Bot. 38(2): 163-169, 2009 (December)

Ethephon for induction of multiple tubers in water yam (D. alata)

Yam cultivar Gunung (Dioscorea alata) is resistant to anthracnose (Colletotrichum gloeosporioides Penz.). It has an extraordinary yield potential. Yet its acceptability has been limited because of the frequent production of large-sized and off-shaped tubers which are difficult to market. Local growers will increasingly accept this cultivar if tuber size can be reduced without an undue loss in yield. A study was conducted to determine whether ethephon [(2-chloroethyl) phosphonic acid] can induce multiple stem sprouting and hence multiple tuber production as a means of reducing tuber size and improving shape. Head, middle, and tail tuber sections were treated with a 1% ethephon solution and planted in the field. The ethephon treatment significantly increased stem sprouting in the middle and tail sections but not in the head section. A significant reduction in mean tuber weight was observed in all treated sections. However, this reduction was compensated for by a significant increase in the number of tubers produced per plant. The hormone treatment did not significantly affect total yield but did lead to more production of uniform tubers. Mean yield of marketable tubers was 73,123 kg/ha.