Rate Of Dry Matter Accumulation Research Articles

Effect of harvest period on the quality of storage roots and protein content of the leaves in five cassava cultivars (Manihot esculenta, Crantz)

The effect of harvest period on the quality of storage roots and leaves of cassava cultivars was determined in an experiment carried out in a randomized complete block design with four replications in a split plot scheme, with five cultivars in the plots and ten harvest times in the subplots. The IAC 13 cultivar had the highest rate of dry matter accumulation in the storage roots and the Mico cultivar the lowest. The period of least dry matter content in the storage roots occurred later for the Fécula Branca, Mico and IAC 14 cultivars, and the minimum starch content in the storage roots occurred later for the Fécula Branca and Mico cultivars. In general, the IAC 13, IAC 14 and Fécula Branca cultivars had higher dry matter content in the storage roots, while higher starch content in the dry and fresh matter were obtained in the Fécula Branca cultivar. The crude protein content in the leaves decreased as the plant aged.

Características agronômicas produtivas, qualidade e custo de produção de forragem em pastagem de azevém (Lolium multiflorum Lam) fertilizada com dois tipos de adubo

Um experimento foi conduzido, com o objetivo de avaliar o comportamento produtivo e qualitativo, bem como, o custo de produção de forragem da pastagem de azevém comum, em pastejo contínuo, fertilizada com dois tipos de adubos: Organo-mineral (AOM) e Químico (AQ). O estabelecimento da pastagem foi em 24/04/1999, com semeadura a lanço e o nível de adubação, em cobertura, foi de 300kg ha-1 do AOM na fórmula 06-08-08 ou do AQ na fórmula 10-18-20. Não houve interação significativa entre os fertilizantes e período de avaliação para as variáveis estudadas. A fonte de nutrientes, para os valores médios, não afetou significativamente o teor de matéria seca (MS) no resíduo (22,6 vs 22,2%), a taxa de acumulação diária (72,3 vs 63,3kg ha-1 de MS), a produção total de forragem (7.518 vs 6.801kg ha-1 de MS), o teor de proteína bruta (12,8 vs 12,7%), a fibra em detergente neutro (57,4 vs 57,4%) e a fibra em detergente ácido (31,0 vs 32,3%), respectivamente, para o AOM e AQ. O custo total da pastagem foi de 225,90 e 253,50 R$ ha-1, e a fonte de nutrientes representou 37,6 e 44,4%, respectivamente, para o AOM e AQ. Para o custo de forragem produzida, os valores foram de 0,030 e 0,037 R$ kg-1 de MS para a pastagem fertilizada com AOM e AQ, respectivamente.

サツマイモ塊根の肥大に対する根温の影響 直接的および間接的な温度の影響

Root temperature effects on tuberous root growth of sweetpotato were examined using a hydroponic system where the temperature conditions of shoot, tuberous root and fibrous roots were controlled independently. Plants were grown under various root temperature conditions of 24/24, 24/28, 28/28, 32/28 and 32/32°C (tuberous root temp./fibrous root temp.), and volume changes in the tuberous root were measured on-line. Growth of fibrous roots was also examined for 16, 20, 24, 28 or 32°C of fibrous root temperature in another experiment. In all the experiments, shoot environment was controlled at 28°C, 70% RH, PPFD 300 μmol m-2s-1and a photoperiod of 12 h. In the fibrous roots, rates of elongation and dry matter accumula-tion were enhanced by an increase in the temperature. In the tuberous root, rates of growth and dry matter accumulation were higher in the temperature combinations of 24/24°C and 28/28°C, and extremely lower in 24/28°C and 32/32°C. The inhibition of the tuberous root growth in those temperature conditions was found to be caused by changes in ratio of carbon partitioning between the tuberous root and the fibrous roots in relation to sink strength of fibrous root. Based on our findings, the tuberous root growth of sweetpotato is sensitive to growth activity of fibrous root.

Simulating growth, development, and yield of tillering pearl millet. III. Biomass accumulation and partitioning

Pearl millet landraces from Rajasthan, India, yield significantly less than improved cultivars under optimum growing conditions, but not under stressed conditions. To successfully develop a simulation model for pearl millet, capable of capturing such genotype×environment (G×E) interactions for grain yield, we need to understand the causes of the observed yield interaction. The aim of this paper is to quantify the key parameters that determine the accumulation and partitioning of biomass: the light extinction coefficient, radiation use efficiency (RUE), pattern of dry matter allocation to the leaf blades, the determination of grain number, and the rate and duration of dry matter accumulation into individual grains. We used data on improved cultivars and landraces, obtained from both published and unpublished sources collected at ICRISAT, Patancheru, India. Where possible, the effects of cultivar and axis (main shoot vs. tillers) on these parameters were analysed, as previous research suggested that G×E interactions for grain yield are associated with differences in tillering habit. Our results indicated there were no cultivar differences in extinction coefficient, RUE, and biomass partitioning before anthesis, and differences between axes in biomass partitioning were negligible. This indicates there was no basis for cultivar differences in the potential grain yield. Landraces, however, produced consistently less grain yield for a given rate of dry matter accumulation at anthesis than did improved cultivars. This was caused by a combination of low grain number and small grain size. The latter was predominantly due to a lower grain growth rate, as genotypic differences in the duration of grain filling were relatively small. Main shoot and tillers also had a similar duration of grain filling. The low grain yield of the landraces was associated with profuse nodal tillering, supporting the hypothesis that grain yield was below the potential yield that could be supported by assimilate availability. We hypothesise this is a survival strategy, which enhances the prospects to escape the effects of stress around anthesis.

Ajuste da carga animal em experimentos de pastejo: uma nova proposta

A variação na massa de forragem disponível é freqüentemente observada em experimentos de pastejo, conduzidos sob uma oferta de forragem fixa. Para um melhor controle da massa de forragem, propõe-se uma nova forma de ajuste da carga animal, baseada nos parâmetros massa e oferta de forragem, taxa de acúmulo e consumo de matéria seca (MS), e forragem passível de rejeição e perdida. Este método foi utilizado no Departamento de Zootecnia da UFSM, num experimento de pastejo em milheto sob doses de nitrogênio (0, 150, 300, 450 e 600kg ha-1), visando manter uma massa de forragem de 2500kg MS ha-1 durante o período de avaliação. A taxa de acúmulo de MS foi avaliada a cada 28 dias através de gaiolas de exclusão. O material passível de rejeição, medido em quadrados fixos, representou de 33 a 57% da massa de forragem, sendo dependente das doses de nitrogênio e da carga animal. O método utilizado foi eficiente na manutenção da massa de forragem pretendida, indicando a potencialidade do seu uso em experimentos em que se pretende um maior controle das variáveis envolvidas na interface planta-animal.

Potassium uptake efficiency of young plants of three potato cultivars as related to root and shoot parameters

Three potato cultivars, Kufri Badshah, Kufri Chandramukhi, and Kufri Jyoti were grown in low potassium (K) soil with and without K in a pot experiment to test their K uptake efficiency. Two harvests were taken to obtain final dry matter accumulation (DMA) rates of shoot and root growth and K uptake per unit root (K-influx). Relative DMA without K (expressed as percent of DMA with K) was 66, 75, and 90% for Kufri Badshah, Kufri Jyoti, and Kufri Chandramukhi, respectively, showing that Kufri Chandramukhi had a higher K uptake efficiency than other cultivars. High K uptake efficiency of Kufri Chandramukhi was due to its high K-influx while low K uptake efficiency of Kufri Badshah and Kufri Jyoti was due to low K-influx which nullified the effect of their high root-shoot (DMA) ratio. The potassium efficient cultivar, Kufri Chandramukhi, utilized more K from non-exchangeable soil source (46%) than Kufri Jyoti (25%) or Kufri Badshah (17%).

Carboidratos não estruturais e acúmulo de forragem em pastagens de Cynodon spp. sob lotação contínua

Reservas orgânicas são compostos capazes de determinar o vigor e a velocidade da rebrota de plantas forrageiras influenciando sua persistência na pastagem. Dentre os compostos constituintes das reservas orgânicas estão os carboidratos não estruturais (CNE). Os teores e a quantidade de CNE foram avaliados em amostras de pastagens de 'Tifton-85', 'Florakirk' e 'Coastcross', estabelecidas em Nitossolo Vermelho eutroférrico, durante as estações de inverno, primavera e verão. Os tratamentos corresponderam a quatro situações de "steady state" do relvado, caracterizadas por alturas de pasto de 5, 10, 15 e 20 cm mantidas por ovinos sob regime de lotação contínua. O delineamento experimental foi em blocos completos casualizados, com um arranjo de parcelas subdivididas e quatro repetições. Os cultivares foram alocados nas parcelas e alturas de pasto nas subparcelas. As coletas das amostras para determinação de CNE foram realizadas mensalmente utilizando-se tubos de aço de 15 cm de diâmetro por 50 cm de altura. Os teores de CNE foram quantificados através de metodologia analítica baseada em digestão ácida e as taxas de acúmulo de matéria seca foram mensuradas através de gaiolas de exclusão. Os cultivares de Cynodon spp. avaliados apresentaram um padrão de variação sazonal quanto à prioridade de alocação de CNE para os órgãos de reserva (base do colmo e raízes). Os teores de CNE obtidos não atingiram níveis que pudessem ser considerados danosos à perenidade e à produtividade das pastagens de 'Tifton-85', 'Florakirk' e 'Coastcross'. 'Tifton-85' apresentou maior quantidade de CNE na base do colmo e raízes, o que poderia contribuir para uma maior tolerância a períodos de estresse.

Strawberry Growth and Development in an Annual Plasticulture System

The growth and development of three strawberry cultivars commonly grown in a plasticulture system were documented. Strawberry plants were harvested monthly and divided by roots, crown, leaves, flowers, and fruit and then dried in an oven. The dry matter production and resource allocation proceeded along a predictable pattern of development. The establishment phase was characterized by an active period of growth of root, crown and leaves in the fall. Through the winter, the plants underwent slow growth, ending in a transition period in the late winter/early spring when resources were allocated to both vegetative and reproductive growth. In the spring, all plant parts received significantly increased allocation of, or redistribution of, resources. Cultivars of California origin, `Chandler' and `Camarosa', displayed similar trends in yield, dry matter production, seasonal resource allocation, and growth analysis variables throughout the season. `Sweet Charlie', a cultivar from Florida, showed lower dry matter accumulation and relative growth rate in the spring, higher harvest index and lower yield than the California cultivars.

Evaluation of potato (Solanum tuberosum) cultivars for productivity, nitrogen requirement and eco-friendly indices under different nitrogen levels

A field experiment was conducted during the winter ( rabi) seasons of 201112 and 201213 at Adisaptagram Block Seed Farm, Hooghly, West Bengal, to optimize the potato ( Solanum tuberosum L ) cultivars and nitrogen lev- . els for growth attributes, tuber yield, nitrogen-use efficiency, sustainability, eco-friendliness and economics in new . alluvial zone of West Bengal. Fifteen treatment combinations, viz 3 potato cultivars (Kufri Himalini, Kufri Shailja and Kufri Jyoti) and 5 N doses (0, 75, 150, 225 and 300 kg N/ha) were laid out in a factorial randomized block de- sign with 4 replications. Kufri Himalini recorded the maximum tuber yield (31.3 t/ha), which was significantly higher than Kufri Shailja (26.6 t/ha) and Kufri Jyoti (24.1 t/ha). Correlation between tuber yield and plant height (R2=0.73), tuber yield and dry matter accumulation (R2=0.84), tuber yield and tuber bulking rate (R2=0.75) and tu- ber yield and total N uptake (R2=0.62) were significant. The correlation study between nitrogen and tuber yield showed high degree of correlation (R2=0.984) and N was derived as 202.6 kg N/ha for optimum economic yield. opt. Agronomic efficiency (AE ) and physiological efficiency (PE ) was more in Kufri Himalini at all N levels. There was N N a positive balance of nitrogen in all the treatments except one treatment (Kufri Jyoti with 300 kg N/ha). Kufri Himalini fertilized with 300 kg N/ha gave the highest net returns ( 1,45,156/ha) and benefit: cost ratio (2.58) with least difference from 225 kg N/ha, while the negative response was recorded in the control. Kufri Shailja potato was more eco-friendly, as its index was 18.4% higher than Kufri Jyoti. Kufri Shailja required 18.4% less applica- tion of fertilizer N to give the highest yield obtained by Kufri Jyoti (30.94 t/ha). So, for obtaining a given yield, less amount of fertilizer is being put to soil and hence comparatively less amount of N is being lost to the environment.

Evaluation of potato (Solanum tuberosum) cultivars for productivity, nitrogen requirement and eco-friendly indices under different nitrogen levels

A field experiment was conducted during the winter ( rabi) seasons of 201112 and 201213 at Adisaptagram Block Seed Farm, Hooghly, West Bengal, to optimize the potato ( Solanum tuberosum L ) cultivars and nitrogen lev- . els for growth attributes, tuber yield, nitrogen-use efficiency, sustainability, eco-friendliness and economics in new . alluvial zone of West Bengal. Fifteen treatment combinations, viz 3 potato cultivars (Kufri Himalini, Kufri Shailja and Kufri Jyoti) and 5 N doses (0, 75, 150, 225 and 300 kg N/ha) were laid out in a factorial randomized block de- sign with 4 replications. Kufri Himalini recorded the maximum tuber yield (31.3 t/ha), which was significantly higher than Kufri Shailja (26.6 t/ha) and Kufri Jyoti (24.1 t/ha). Correlation between tuber yield and plant height (R2=0.73), tuber yield and dry matter accumulation (R2=0.84), tuber yield and tuber bulking rate (R2=0.75) and tu- ber yield and total N uptake (R2=0.62) were significant. The correlation study between nitrogen and tuber yield showed high degree of correlation (R2=0.984) and N was derived as 202.6 kg N/ha for optimum economic yield. opt. Agronomic efficiency (AE ) and physiological efficiency (PE ) was more in Kufri Himalini at all N levels. There was N N a positive balance of nitrogen in all the treatments except one treatment (Kufri Jyoti with 300 kg N/ha). Kufri Himalini fertilized with 300 kg N/ha gave the highest net returns ( 1,45,156/ha) and benefit: cost ratio (2.58) with least difference from 225 kg N/ha, while the negative response was recorded in the control. Kufri Shailja potato was more eco-friendly, as its index was 18.4% higher than Kufri Jyoti. Kufri Shailja required 18.4% less applica- tion of fertilizer N to give the highest yield obtained by Kufri Jyoti (30.94 t/ha). So, for obtaining a given yield, less amount of fertilizer is being put to soil and hence comparatively less amount of N is being lost to the environment.

Effect of Pulp Cell Number and Assimilate Availability on Dry Matter Accumulation Rate in a Banana Fruit [ Musa sp. AAA group ‘Grande Naine’ (Cavendish subgroup)

Fruit position on the bunch (inflorescence) is an important part of variability in banana fruit weight at harvest, as fruits at the bottom of the bunch (distal fruits) are approx. 40% smaller than those at the top (proximal fruits). In this study, the respective roles of cell number and cell filling rate in the development of pulp dry weight are estimated. To this end, the source/sink ratio in the plant was altered at different stages of fruit development. Leaf shading (reducing resource availability), bunch bagging (increasing sink activity by increasing fruit temperature), and bunch trimming (decreasing sink size by fruit pruning), applied once cell division had finished, showed that the pulp filling rate depends on resource availability. Bunch bagging and bunch trimming were also carried out before the end of cell division to estimate the role of pulp cell number in the development of pulp dry weight. A sampling method was calibrated to evaluate pulp cell number from the digestion of a fixed portion of the pulp in a solution of chromic and nitric acids. A relationship was found between pulp cell number and fruit length at the end of cell division. It was observed that pulp cell number is a determining factor in pulp dry weight variability within a bunch. On the other hand, the cell filling rate was identical for all fruits in the bunch and was influenced by the source/sink ratio. A Michaelis-Menten relationship was invoked to relate the cell filling rate in a bunch to the source/sink ratio during bunch filling.

Wheat/maize or wheat/soybean strip intercropping: II. Recovery or compensation of maize and soybean after wheat harvesting

While early-maturing crops benefit from intercropping, late-maturing crops usually suffer growth penalties during the intercropping phase. It is possible, however, that recovery or compensation of the late-maturing crops occurs after the harvest of the early-maturing crops. Three field experiments were conducted at Baiyun in 1997 and at Jingtan in 1997 and 1998 to test the hypothesis in wheat/maize and wheat/soybean intercropping. The biomass and nutrient accumulation in intercropped soybean were significantly smaller than in sole soybean before wheat harvest but thereafter increased sharply at Jingtan site in 1997. The rates of dry matter accumulation in the intercropped maize (10.0–20.1 g/m 2 per day) were significantly lower than those in the sole maize (17.1–34.8 g/m 2 per day) during the early stage from 7 May to 3 August, while mostly intercropped with wheat. After 3 August, however, the rates of intercropped maize, increasing to 58.9–69.9 g/m 2 per day, was significantly greater than in sole maize (22.7–51.8 g/m 2 per day) at Baiyun site in 1997 and nutrient acquisition showed the same trends as growth. At Jingtan site in 1998, the disadvantage of the border row of intercropped maize resulted from interspecific competition diminished after wheat harvest and disappeared at maize maturity. It was concluded that there was indeed recovery of growth after wheat harvesting in wheat/maize and wheat/soybean intercropping. However, the recovery was limited under N 0P 0 treatment. The interspecific competition, facilitation and recovery are together contributed to yield advantage of intercropping.

Effects of the ‘Stay Green’ Genotype GGd1d1d2d2 on Leaf Gas Exchange, Dry Matter Accumulation and Seed Yield in Soybean (Glycine max L. Merr.)

The homozygous combination of the recessive mutations d1 and d2, i.e.d1d1d2d2 , causes retention of chlorophyll, chlorophyll-binding proteins and Rubisco in senescing leaves of soybean (Glycine max L. Merr.). Together with G(a gene that preserves only chlorophyll in the mature seed coat), d1d1d2d2 prolonged photosynthetic activity and increased seed yield in growth chamber experiments. The objective of this work was to test the effects of GGd1d1d2d2(abbreviated to Gd1d2) on leaf gas exchange, growth and seed yield in soybean plants cultured outdoors during the normal growing season. Despite preservation of the photosynthetic machinery in Gd1d2, photosynthesis during the seed filling period was similar in Gd1d2 and its near-isogenic wild type line ‘Clark’. The main factor limiting photosynthesis in the mutant appeared to be stomatal conductance, which was substantially lower in Gd1d2 than in ‘Clark’. In Gd1d2 the rate of dry matter accumulation during the seed filling period was similar or lower than in the wild type. At maturity, Gd1d2 had fewer nodes, fruiting nodes, fruits and seeds per plant, and therefore its seed yield was reduced by 10–20% compared to ‘Clark’. Thus, pleiotropic effects of G, d1 and/or d2 affecting stomatal conductance and seed number appear to be major limitations to the yield potential of Gd1d2. These pleiotropic effects suggest thatG , d1 and/or d2 have regulatory functions in addition to the control of chloroplast disassembly during senescence.

Demografia do perfilhamento e acúmulo de matéria seca em coastcross submetido a pastejo

Os objetivos deste trabalho foram identificar o padrão populacional do perfilhamento de coastcross (Cynodon spp. cv. Coastcross) sob pastejo, e avaliar o acúmulo de matéria seca de sua forragem. Foram avaliados densidade populacional, taxas de natalidade e mortalidade de perfilhos, proporção de perfilhos florescidos e acúmulo de matéria seca. Os tratamentos consistiram em manter a altura do pasto em 5, 10, 15 e 20 cm, utilizando ovinos sob regime de lotação contínua e taxa de lotação variável. Pastos mais baixos (5 cm) apresentaram as maiores densidades populacionais de perfilhos. O florescimento foi mais intenso durante o final do inverno e início da primavera. Ocorreu alta renovação de perfilhos durante o verão. As condições de seca promoveram fortes efeitos sobre as taxas de natalidade e de mortalidade de perfilhos. Não houve efeito (P>0,10) de tratamento sobre as taxas de acúmulo de matéria seca.

DINÂMICA, QUALIDADE, PRODUÇÃO E CUSTO DE PRODUÇÃO DE FORRAGEM DA MISTURA AVEIA PRETA E AZEVÉM ANUAL ADUBADA COM DIFERENTES FONTES DE NITROGÊNIO

O experimento foi conduzido na Depressão Central do Rio Grande do Sul, de 21/04 a 02/06/94 (estabelecimento da pastagem) até 11/06/94 (período de utilização), com o objetivo de avaliar a dinâmica, a produção, a qualidade de forragem e o custo de produção da pastagem de aveia preta mais azevém, em pastejo contínuo, fertilizada com diferentes fontes de nitrogênio (uréia e sulfato de amônio) em cobertura. A mistura foi semeada de forma direta e adubada com 200kg/ha da fórmula 05-30-15. O nível de nitrogênio em cobertura foi de 200kg/ha para ambas as fontes, sendo parceladas em três aplicações. A fonte de nitrogênio não afetou, significativamente, a taxa de acumulação diária de matéria seca (MS) (38,7 e 36,1kg/ha de MS/dia), a produção total de forragem (7.410 e 6.618kg/ha de MS) e a qualidade da forragem. A porcentagem de MS foi de 18,26 e 18,47%, o teor de proteína bruta, de 22,14 e 22,69% e a digestibilidade in vitro da matéria orgânica, de 57,85 e 57,04% para uréia (U) e sulfato de amônio (SA), respectivamente. O custo total/ha da pastagem foi de R$295,70 e R$379,40; o N representando 36,08 e 50,20%, para uréia e sulfato de amônio, respectivamente. O custo/quilograma de MS produzida foi de R$0,039 e R$0,057 para pastagem em que foi utilizado a uréia e o sulfato de amônio, respectivamente. Conclui-se que, em pastagem de gramíneas anuais de inverno, a escolha da fonte de N deve ser baseada no custo/kg de N.

Oferta de forragem de capim-elefante anão 'Mott' e o rendimento animal

A pesquisa foi realizada durante as estações de crescimento de 1994/95 e 1995/96 (out./abr.), na Estação Experimental de Ituporanga/EPAGRI - SC, objetivando determinar o potencial de produção animal e as respostas em termos de taxa de acúmulo de matéria seca (MS) e qualidade de forragem e estrutura do perfil de uma pastagem de capim-elefante anão `Mott' (CEAM) submetida a quatro níveis de oferta de forragem (OF). Os níveis reais de FO foram 3,8; 7,5; 10,2 e 14,0 kg de MS de lâminas verdes (MSLV)/100 kg de PV/dia, num delineamento em blocos casualizados completos com duas repetições e três novilhos (8 a 10 meses) por potreiro, sob pastejo contínuo e uso da técnica "put-and-take". As OF determinaram resíduos médios de MSLV (RMSLV) de 722; 1537; 2332; e 2542 kg/ha, respectivamente. Ofertas de forragem crescentes condicionaram acréscimos na taxa de acúmulo de MSLV/ha/dia e na densidade da forragem. A OF de 11,3 kg de MSLV/100 kg de PV/dia (RMSLV de 2200 kg/ha) maximiza o desempenho animal com 1,06 kg/dia de ganho médio diário e assegura ganho/ha de 5,6 kg/dia, em condição de sustentabilidade da pastagem de CEAM, em pastejo contínuo.

Acid phosphomonoesterase and phytase activities of wheat (Triticum aestivum L.) roots and utilization of organic phosphorus substrates by seedlings grown in sterile culture

ABSTRACTWheat seedlings exhibited a differential ability to utilize P from a range of organic P substrates when grown in agar culture under sterile conditions. Plants showed limited ability to obtain P from inositol hexaphosphate (IHP), whereas other monoester substrates such as glucose 1‐phosphate (G1P), were equivalent sources of P for plant growth as compared with inorganic phosphate (Pi). Poor utilization of IHP was exemplified by significantly lower rates of dry matter accumulation and reduced P content of tissues, which were generally not significantly different to control plants that were grown in the absence of added P. The inability of wheat seedlings to obtain P from IHP was not associated with poor substrate availability but was due to either insufficient root phytase activity or inappropriate localization of phytase within root tissues. Phytase activities of 4 and 24 mU g−1 root fresh weight (FW) were determined for crude root extracts prepared from plants that were grown with either adequate P or under deficient conditions, respectively. Similar levels of phytase activity (approximately 12 mU g−1 FW) were observed in assays using intact roots, although no secreted activity was detected. By comparison, a secreted acid phosphomonoesterase activity was observed, and activities of between 466 and 1029 mU phosphomonoesterase g−1 root FW were measured for intact roots. On the basis of the differences in enzyme activity, and the observed differences in the ability of wheat seedlings to utilize G1P and IHP, it is evident that low intrinsic levels of phytase activity in wheat roots is a critical factor that limits the ability of wheat to obtain P from phytate when supplied in agar under non‐limiting conditions. This hypothesis was further supported by the observation that the ability of wheat to obtain P from IHP was significantly improved when the seedlings were inoculated with a soil bacterium (Pseudomonas sp. strain CCAR59) that possesses phytase activity.

The Effect of Superovulation of Javanese Thin-Tail Ewes Prior to Mating on Lamb Birth Weight and Preweaning Growth

There is little information on optimum management of fodder tree legumes for maximum leaf production. The type of management depends on both their morphology and form of utilisation, which varies between species. As differences exist in relative growth rates and ability to persist over longer periods, their management is influenced by cutting height and cutting frequency (Horne et al., 1986). This study was undertaken at the University of Queensland to observe the responses of commonly used fodder tree legumes to cutting management. Four cutting treatments (60 cm, 100 cm, 150 cm and lopped) commencing in August, 1987 were imposed on five established tree legume species (Acacia angustissimus, Calliandra calothrysus, Albizia chinensis, Gliricidia sepium and Leucaena leucocephala). Each row of species contained five trees per treatment. Two months later the trees were cut at their respective heights and coppiced material lopped and subsequent harvests made at 1.5 monthly intervals until March. Materials harvested were separated into leaf (including flowers and pods) and stems (>6 mm diameter) and oven dried at 60C. The low spring temperatures reduced and inhibited leaf growth of all species and G. sepium respectively, but improved during summer. At 150 cm, L. leucocephala was better during spring and all species produced similar yields during summer. The overall mean leaf yields (%) at the respective heights over the period were 19, 26, 36, 19; 13, 24, 43, 19; 14, 22, 44 and 20. When lopped, leaf yield of C. calothrysus was high during spring and summer but similar to A. chinensis and G. sepium respectively in terms of forage quality. The overall mean leaf yields over the period were 7, 16, 10 and 65%. As cutting height increased, the number of remaining shoots, leaves and buds in the bottom canopy also increased from which regrowth was rapid. However, the proportion of leaves removed either by cutting, lopping or loss through leaf fall removed most photosynthetic tissues and reduced current photosynthate, resulting in reduced leaf yield. Regrowth and plant survival then depended on the reserve carbohydrate in the stem and rate of dry-matter accumulation, which varied between species. The different responses to cutting management provided some options for their use as reserve fodder in grazing systems. Horne, PM Catchpole D W and Ella A 1986 ACIAR

Growth and Canopy Characteristics of Field‐Grown Tomato

Although detailed growth studies and yield analysis are common for agronomic crops, their application to horticultural crops is limited. Detailed growth measurements of field‐grown tomato (Lycopersicon esculentum Mill.) were conducted at four Florida locations for two irrigation methods. Maximum rate of main‐stem node development was ≈0.5 nodes d−1 and leaf area index (LAI) increased exponentially with main‐stem node number. Maximum LAI was attained 11 wk after transplanting, with values ranging from 1.5 to 3.0 and from 3.2 to 6.0 for drip‐irrigated and subirrigated crops, respectively. Lower LAI values with drip irrigation were only partially related to wider row spacings. Final biomass (dry weight) ranged from 6 to 12 Mg ha−1 and fruit dry weight harvest indices (fruit biomass/total above‐ground biomass) ranged from 0.53 to 0.71. Average dry matter accumulation by roots, stems, and leaves accounted for ≈3, 23, and 17% of final biomass, respectively. Estimated radiation use efficiency (RUE) for tomato averaged 1.05 g dry weight MJ−1 m−2, with 50 to 60% light interception in the crop production area at LAI values of 4 to 5. At 11000 plants per ha, the rate of dry matter accumulation averaged 17.8 g d−1 m−2 during the linear growth phase, with instantaneous dry matter partitioning to fruits averaging 0.70 during the fruit‐growth phase. Relationships between degree days, estimated cumulative intercepted radiation, and fruit yield accounted for much of the variation in fruit yields for these different seasons and locations throughout Florida.

Relationship between Water Content and Growth of Seed and Fibre of Three Cotton Genotypes

Three cotton genotypes (varying in their final seed size), viz. H‐6 and H‐4 (Gossypium hirsutum L.) and V‐797 (Gossypium herbaceum L.) were studied for their growth kinetics of seed and fibre. Both biphasic linear and polynomial models were used to demark different phases of cotton seed growth. The polynomial model appeared to be appropriate to define the growth phases of cotton seed as compared to the linear model. The rate and the duration of dry matter accumulation were obtained by differentiating the best‐fit polynomial equations. Based on the data of dry weight and water content, cotton seed development is divided into four different phases, viz. (a) cell division, (b) cell elongation, (c) dry matter accumulation and (d) maturation. The rate of dry matter accumulation showed a close correlation with water content of seed as well as of the fibre, in all three genotypes studied. It is proposed that water content of seed or fibre plays an important role in determining dry weight of three genotypes.