Rate Of Dry Matter Accumulation Research Articles

Produção de forragem em pastagens consorciadas com diferentes leguminosas sob pastejo rotacionado

The objective of this research was to evaluate two pasture-based systems, with elephantgrass, ryegrass, white clover or forage peanut and spontaneous growth species about the accumulation rate and of disappearance of forage mass. The elephantgrass was established in rows with a distance of 4 m between rows. In the cool season, ryegrass was planted between rows of elephantgrass; white clover was sowed,in two paddocks, and in the other two the forage peanut was preserved. The experimental design was completely randomized. In order to stipulate the accumulation rate and of disappearance of forage mass, the pre- and post-graze forage mass were evaluated. The botanical and structural composition, as well as the stocking rate were analyzed. The average rate of accumulation and disappearance of forage mass and the stocking rate were of 47.29 kg of DM ha -1 day -1 ; 3.24% and 3.10 UA ha -1 and of 53.16 kg of DM ha -1 day -1 ; 3.45% and 3.48 UA ha -1 to the systems formed by white clover and forage peanut, respectively. Considering the accumulation rate of the pasture dry matter, the disappearance of forage mass and the stocking rate, the forage system associated with forage peanut showed a better performance

Growth, Development and Dry Matter Accumulation in the Fruit of <i>Cocos nucifera</i> L. var <i>nana</i> form <i>pumila</i>

The growth and development, from fertilization to maturity, of the fruit of Cocos nucifera var. Nana form pumila and its components, were studied in terms of dry matter accumulation. The development of the fruit showed an approximately sigmoidal pattern with a substantial linear phase during which most of the increase in dry weight occurred. During the linear phase of growth the rate of dry matter accumulation by the whole fruit was about 70.9g/ month. A linear phase was evident in the growth curves of each of the fruit components husk, shell, and endosperm. The growth curves of these components also conformed to a sigmoid pattern. The husk, shell and endosperm commenced growth in the first, fifth and sixth months respectively. Over the 11 month period of fruit development the three components grew simultaneously only over a three month period from five to eight months after fertilization. The rapid growth phase of the husk, shell and endosperm extended from three to seven months, five to nine months and six to ten months, respectively. During this linear growth phase the average growth rate of the endosperm was 39.9g/ month and the highest rate of growth was 53.1g / month in the ninth month. At maturity the total fruit dry weight was 476g with the husk contributing 41.9%, the shell 22.5% and the endosperm 35.6%. COCOS, (1985) 3 16-21 doi: 10.4038/cocos.v3i0.817

Accumulation of Dry Matter and Nitrogen in Durum Wheat During Grain Filling as Affected by Temperature and Nitrogen Rate

Durum wheat (Triticum durum Desf.) is commonly grown in mediterranean conditions, where temperature stress during grain filling can limit productivity. This study was conducted to assess the effect of optimal and too high temperature during grain filling on the patterns of accumulation of dry matter and N of durum wheat plants grown at different levels of N fertilization. Two durum wheat varieties, Appio and Creso, were grown in controlled environment conditions and in pots with three rates of nitrogen fertilizer (not applied, normal amount, and high amount) and two air temperature regimes during grain filling (20/15 °C and 28/23 °C day/night). Results showed that the duration of the intervals between the main maturity stages within grain filling were both genotype-specific and temperature-dependent, while N rate did not modify the timing of grain development. The two genotypes responded to temperature by increasing the rate of development, but the thermal timing of development was unchanged with the two temperature regimes. The higher temperature reduced grain growth and increased N accumulation in grain. However, these effects were recorded only in fertilized plants. Nitrogen availability modified the growth of the plant during the whole cycle, in that increased N fertilizer at seeding resulted in a greater plant size at anthesis and in a greater accumulation rate of dry matter and N in grain during grain filling. Grain yield and kernel weight were better expressed at 20/15 °C, while grain protein concentration was favoured under the 28/23 °C temperature regime. Nitrogen fertilization increased the sensitivity of plants to high temperature. Thus, the role of N fertilization under heat stress may be more important than under optimal temperatures.

Nutrient uptake and biomass accumulation for eleven different field crops

Oil hemp (Cannabis sativa L.), quinoa (Chenopodium quinoa Willd.), false flax (Camelina sativa (L.) Crantz), caraway (Carum carvi L.), dyer’s woad (Isatis tinctoria L.), nettle (Urtica dioica L.), reed canary grass (RCG) (Phalaris arundinacea L.), buckwheat (Fagopyrum esculentum Moench), linseed (Linum usitatissimum L.), timothy (Phleum pratense L.) and barley (Hordeum vulgare L.) were grown under uniform conditions in pots containing well fertilised loam soil. Dry matter (DM) accumulation was measured repeatedly, and contents of minerals N, P, K, Ca and Mg at maturity. Annual crops accumulated above-ground biomass faster than perennials, while perennials had higher DM accumulation rates below ground. Seeds had high concentrations of N and P, while green biomass had high concentrations of K and Ca. Stems and roots had low concentrations of minerals. Concentrations of K and P were high in quinoa and caraway, and that of P in buckwheat. Hemp and nettle had high Ca concentrations, and quinoa had high Mg concentration. N and P were efficiently harvested with seed, Ca and K with the whole biomass. Perennials could prevent soil erosion and add carbon to the soil in the long term, while annuals compete better with weeds and prevent erosion during early growth. Nutrient balances in a field could be modified and nutrient leaching reduced by careful selection of the crop and management practices.;

Winter triticale yield formation and quality affected by N rate, timing and splitting

The field experiment was conducted to study the effects different nitrogen (N) quantities (N0–120 kg ha-1) and application regimes (N applied at stages of tillering BBCH28–30 and flag leaf sheath opening BBCH47) on (i) the formation of winter triticale above ground biomass (AGB), (ii) the grain yield (iii) the yield quality, and also (iiii) to find more suitable N fertilizing regimes for winter triticale depending on their utilization. Winter rye and winter wheat were used as reference crops. The efficiency of applying all N at the tillering stage (N100%+N0) was the highest for the grain yield of triticale. N application at development stage of plants BBCH47 increased the grain protein concentration significantly and the increase by 1 kg N was the highest in triticale cultivars. More stabile grain yield was produced by triticales in application regime N+N. N splitting did not influence significantly either the duration of the grain-filling period or the dry matter accumulation rate of triticale. N splitting affected Hagberg falling number (HFN) indirectly through the effect on the grain yield formation and grain protein concentration. HFN was positively correlated with the grain yield and negatively with the grain protein concentration. The suitable N regimes are: 1) triticale as the energy plant – N60+N0 – N applied at the tillering stage of plants and suitable N norm is not more than 60 kg N ha-1; 2) triticale as a feed or food – N60+N60 – High grain yield, protein and lysine concentration level are assured then.;

Mechanisms Involved in Soybean Rust‐Induced Yield Reduction

Soybean rust (SBR; caused by Phakopsora pachyrhizi Syd. and P. Syd.) leads to premature leaf loss and yield reduction. The objectives of this study were to assess effects of SBR infection on soybean [Glycine max (L.) Merrill] yield and to identify causes for the yield reduction. Experiments were conducted in the 2005–2006 and 2006–2007 growing seasons at Londrina, Brazil. The five treatments were SBR infection beginning at either (i) the R2 or (ii) R5 growth stages; nondiseased defoliation treatments to mimic the leaf loss when SBR started at either (iii) the R2 or (iv) R5 growth stages; and (v) a disease‐free, nondefoliated control. The control and defoliation treatments were protected against SBR by fungicide applications. Disease severity, lesion area, and leaf area were monitored from R2 to R7. Biomass and seed yield were measured at maturity. Mean SBR‐induced yield reductions were 67% when infection started at R2 and 37% when infection started at R5. Leaf loss alone reduced yield significantly in only one year and only when defoliation treatments were begun at R2 (31% in 2005–2006). Soybean rust–induced yield loss was attributable to (i) premature leaf loss, (ii) reduction in canopy green leaf area due to SBR lesions, (iii) reduction in dry matter accumulation per unit absorbed radiation by the nonlesion green leaf area, and (iv) reduction in harvest index. The response of harvest index was attributable to reduced seed set and seed mass resulting likely from SBR‐induced reductions in rate of dry matter accumulation.

Relationship between gibberellic acid and water amount in the cotton seed

The role of endogenous GA3 and its application to seed development in two cotton genotypes Hybrid-6 (H-6) (big seeds) and Gujarat cotton 13 (G. Cot) (small seeds) was studied. Kernel and seed coat were subjected to growth analysis in terms of dry weight, water amount, and rates of dry matter accumulation and water uptake. H-6 kernel had manifold higher dry weight and water amount than G. Cot. Seed coat of both genotypes had similar dry weight at maturity, but the maximum rates of dry matter accumulation and water uptake were distinctly higher in H-6. According to growth analysis, development of seed kernel and coat was subdivided into four phases, i.e., cell division, cell elongation, dry matter accumulation and maturation. Endogenous GA3 level was estimated in kernel and seed coat by indirect ELISA using antibodies raised against GA3. GA3 amount per seed components was higher in the seed kernel of H-6 than of G. Cot, except 33 and 36 days after anthesis in kernel. H-6 seed coat had the higher amount of GA3 during cell division phase than that of G. Cot. Close correlation between in vivo GA3 level and water amount was recorded in both seed components. With GA3 or GA3 + NAA treatments in ovule culture, higher promotion in dry weight, water amount and seed size was noted in G. Cot than in H-6 suggesting that G. Cot is more deficient in endogenous GA3. The greatest stimulation of parameters studied was obtained in ovule culture with GA3 + NAA. When GA3 or GA3 + NAA was applied, initial significant difference in water amount and seed size was nullified. Data presented in this study indicated that GA3 regulates cell expansion through the water uptake by cotton seed.

High forage yield and quality of sudan grass ( Sorghum bicolor L.) and pearl millet ( Pennisetum glaucum L.) cultivated in calcareous soils

Sudan grass and pearl millet are major warm season dryland crops, primarily grown for grain production and used as a major source of dietary energy. Both crops are highly water use efficient and belong to the C 4 group of species with high photosynthetic efficiency and dry matter accumulation rates. Both sudan grass and pearl millet have good forage quality, with an adequate crude protein content; that of pearl millet (8.7%) is higher than that of sorghum (6.0%). Therefore, the present investigation was conducted in the Western Delta Region at El-Naubaria, 40 km south of Alexandria, over two successive seasons to evaluate the forage yield and quality of sudan grass and pearl millet. Field experiments were established on calcareous soils, with five fertilization treatments. The results indicate that pearl millet surpassed sudan grass in fresh (6.56 t/ha) and dry yield (2.91 t/ha), which was 8.89% and 5.26% more, respectively, than for sudan grass. As regards the forage quality, pearl millet had good digestibility and was lower in fibre than sudan grass.

Características do pasto e acúmulo de forragem em capim-tanzânia submetido a alturas de manejo do pasto

O objetivo deste experimento foi avaliar alturas de manejo do pasto (20, 40, 60 e 80 cm) em capim-tanzânia (Panicum maximum Jacq.), em regime de lotação contínua, nas características do dossel e acúmulo de matéria seca. Os animais utilizados foram novilhos Nelore (Bos indicus), e a taxa de lotação foi variável. Foram avaliados: a massa de forragem, a massa de lâmina de folha verde, a razão folha:colmo, a composição morfológica e a taxa de acúmulo de matéria seca. O delineamento experimental foi inteiramente casualizado, com duas repetições. A massa de forragem aumentou linearmente com o aumento da altura do pasto. As médias de massa de forragem foram 2.767, 3.105, 3.657 e 4.436 kg ha-1, respectivamente, para as alturas de 20, 40, 60 e 80 cm. As taxas de acúmulo de matéria seca, a 20, 40, 60 e 80 cm, foram, respectivamente, 104, 108, 90 e 81 kg ha-1 por dia, o que indica que houve redução dessas taxas com a elevação da altura do pasto. A razão folha:colmo decresceu linearmente com o aumento da altura do pasto. Pastagens de capim-tanzânia, sob lotação contínua ao final da primavera e durante o verão, devem ser utilizadas entre 40 e 60 cm de altura.

Study of the effect of plant density on the growth of maize ( Zea mays L.) hybrids using the Richards function

In maize, plant density has a considerable influence on the rate of dry matter accumulation and on its partitioning between vegetative and reproductive sinks. The aim of the present research was to use the first, second and third derivatives of the Richards function (RF) for growth analysis on maize hybrids grown at various densities. In two-factorial split-plot experiments carried out in Martonvásár, Hungary in 1997–1999 the growth analysis method was used to examine the effect of six plant densities (20, 40, 60, 80, 100 and 120 thousand plants ha −1 ) on the growth of three maize hybrids (Mara, Mv 355, Florencia) with different vegetation periods. Plant density had a significant effect on the dynamics of dry matter accumulation, absolute growth rate (AGR) and absolute acceleration rate (AAR). There was a significant reduction in the asymptotic maximum (A) and growth parameters (AGR, AAR) of the whole plant and of the individual plant organs (stalk, leaf, ear and grain yield), while the parameters of the leaf area index (LAI) increased significantly with a rise in the plant density. The usefulness of the RF for approximating the growth processes of maize plants and individual plant parts was confirmed statistically.

Transplanting young seedlings in irrigated rice fields: Early and high tiller production enhanced grain yield

Transplanting rice seedlings 20 days old or older has been commonly reported to generate an increase in grain yield as a result of higher tiller production. A series of experiments was conducted at the IRRI farm during the dry and wet seasons to quantify, in a range of plant types, the impact of even younger seedlings and contrasting nursery management on grain yield and to identify plant traits supporting high performance under a given establishment technique. Seedling age at transplanting, ranging from 7 to 21 days, and contrasting nursery types (seedling tray, dapog, mat nursery, and traditional wet-bed seeding) were evaluated for an elite line, a new plant type and hybrid rice. To avoid any confounding effect, sowing date in the nursery, seed rate and crop management in the main field were all the same. In the two seasons, and for all genotypes and nursery types, transplanting older seedlings induced a delay in the onset of linear dry matter accumulation and tiller emergence, while the rate of dry matter accumulation and tiller emergence was unchanged. This delay reduced nitrogen content in the seedlings. Plants recovered quickly, however, after transplanting. The delay also reduced maximum tiller number, and extended crop duration with delayed maximum tillering, flowering and maturity. Grain yield was consistently higher for younger seedlings, with, in some cases, a difference as large as 1 t ha −1 between 7- and 21-day transplanting. This result was valid for the four genotypes evaluated, with a higher impact during the dry season. In contrast, no significant difference was observed for the influence of nursery type on the timing of tiller emergence and on grain yield. Some differences in seedling vigor (plant dry weight, specific leaf area, N content), higher in the case of dapog and wet bed, and in maximum tillering, higher in the case of the seedling tray, however, were observed. But these differences did not have a significant impact on the late increase in crop dry matter and on panicle number at maturity. No significant interaction between seedling age and nursery management for all genotypes and for all the parameters measured was found. Promoting early tiller emergence as a response to transplanting young seedlings increased grain yield in all cases despite the associated decrease in tillering efficiency. Extended growth inside the nursery, rather than transplanting shock per se, appeared to be the main reason for delayed tiller emergence in late transplanting.

RENDIMENTO E VALOR NUTRITIVO DA FORRAGEM OUTONAL DE AMENDOIM-FORRAGEIRO

Dry matter yield and nutritive value of forage le-gume Arachis pintoi (Krap. & Greg.) cv. Alqueire-1 (BRA 037036), was evaluated under different cutting mana-gement regimes and levels of P and K fertilization, in a yellow-red argisoil, at CAP-UFPEL, Capao do Leao, RS, Brazil during Spring-Summer and Fall. Cutting regimes compared were: no cutting, one, two, three, four and five cuttings, at 5 cm above ground. Fertilization levels con-sisted in supplying zero, 50 and 100% of requirements for P and K recommended by Brazilian Soil Science Society, for warm season perennial forage legumes. Fertilization treatments were alocated to main plots and cutting regi-mes to subplots, in a complete splitplot randomized block design, with three replications. Data of the following va-riables were submitted to analysis of variance and polino-mial regression: dry matter yield and quality of autumnal cutting, dry matter accumulation rate of autumnal cutting and total dry matter yield. If the purpose is the utilization of the forage during Autumn, 70% of the recommended phosphorus and potassium fertilization is sufficient to ob-tain maximum forage yield. However, if the objective are cuttings during the growing season (Spring-Summer) and also in Autumn, it is necessary 100% of the recommended fertilization. The increase in number of cuttings during Spring-Summer decreases in the same proportion the fo-rage yield in Autumn. Forage nutritive value in Autumn is better when greater number of cuttings are made during Spring-Summer. Spring deferments also result in higher autumnal forage quality. KEY-WORDS: Cutting, fertilization, tropical forage.

Effects of Site-Specific Nitrogen Management on Yield and Dry Matter Accumulation of Rice from Cold Areas of Northeastern China

Abstract The effects of yield increase and mechanism of site-specific nitrogen management (SSNM) in five rice varieties from cold areas of northeastern China were studied. Plot experiment for critical SPAD value and experiments of two fertilization methods, SSNM and farmer's fertilization practice (FFP) were conducted to study their effects on the quality and dry matter accumulation of rice population, as well as N uptake. Compared with FFP, SSNM significantly decreased the average N rate by 33.8%, significantly increased average ear-bearing tiller rate and LAI for grain-filling stage by 12.3% and 14.1-27.6%, correspondingly, improved dry matter weight and N uptake after heading period by 4.3-29.1% and 11.8-55.1% ( P<0.05), and heightened recovery efficiency and agronomic efficiency by 38.5-133.4% ( P<0.05) and 39.8-194.3% ( P< 0.05), respectively, as well as increased the average yield by 9.8% in 2004 and 2005. The results indicated that the accumulation rate of dry matter and N increased the rice yield and N use efficiency, because of improving rice population quality and increasing LAI after heading period.

Produção e qualidade de pastagens de Coastcross-1 e milheto utilizadas com vacas leiteiras

O uso de pastagens do gênero Cynodon, em propriedades leiteiras do Rio Grande do Sul, tem crescido, especialmente na última década. O objetivo deste trabalho foi comparar a dinâmica, a produção de matéria seca, a qualidade e a composição botânica de pastagens de Coastcross-1 (Cynodon dactylon x C. nlemfluensis) e milheto (Pennisetum americanum) cv. Comum, sob sistema de pastejo rotacionado, com vacas em lactação da raça Holandês. Avaliaram-se a massa de forragem no pré-pastejo (MFPP), a taxa de acúmulo diário de matéria seca (TAD), a produção total de forragem (PTF) e a composição botânica das pastagens. Para o milheto e a Coastcross-1, foram avaliados os componentes estruturais: lâmina foliar (LF), colmo + bainha (CB), outras espécies (OE) e material morto (MM). Na entrada e saída dos animais da pastagem, foram colhidas amostras por simulação de pastejo para determinação dos teores de proteína bruta (PB) e fibra em detergente neutro (FDN). Não houve diferença significativa (P&gt;0,05) para MFPP, TAD, PTF e PB. O milheto apresentou maior disponibilidade de lâminas foliares (P&lt;0,05), menor teor de FDN (P&lt;0,05) na entrada e saída dos animais da pastagem e maior participação de OE (P&lt;0,05). O período total de pastejo foi maior na pastagem de Coastcross-1.

Relationship between gibberellic acid and growth parameters in developing seed and pod of pigeon pea

Changes in endogenous gibberellic acid (GA) levels were determined in developing seeds and pods of pigeon pea (Cajanus cajan). Antibodies against GA3 were raised in rabbits and indirect ELISA developed to estimate GA level. Two varieties, black seeded variety (V1) and B.D.N2 (V2), were selected on the basis of their seed index value. The pod length and number of seeds per pod were significantly different for the two varieties. Dry weight, water content (WC), rate of water accumulation, rate of dry matter accumulation (DMA), and GA content in pod and seed were all larger in V1 than in V2. In both varieties, higher GA content was observed during cell elongation and DMA phases, respective to their varietal differences in growth traits. Relationships between WC and rate of DMA, and WC and GA differed significantly between the two varieties. The results suggest a role of GA and WC in sink-size development in both varieties studied.

Accumulation of Nitrogen and Dry Matter by Soybean Seeds with Genetic Differences in Protein Concentration

ABSTRACTSoybean [Glycine max (L.) Merrill] yields often decline as seed protein levels increase, but the processes responsible are not clearly understood. We compared dry matter and N accumulation by individual seeds of three high protein genotypes (K 1431, KS 4402sp, NE 3396) and three commercial cultivars (Pennyrile, Flyer, Hutcheson) in the field near Lexington, KY (38° 01′ N lat; 84° 35′ W long) for 3 yr to determine if increasing protein concentration decreased the seed growth rate. Plants were grown in 76.2‐cm rows using conventional production practices and overhead irrigation to minimize soil moisture deficits. The rate of dry matter accumulation by individual seeds (SGRDM) varied from 4.2 to 6.1 mg seed−1 d−1 and this variation was closely associated with mature seed size, but it was not affected by seed N concentration. The rate of N accumulation (SGRN, mg N seed−1 d−1) was closely associated with seed N concentration at maturity across all genotypes and years (r2 = 0.76). Thus, SGRN and SGRDM seemed to vary independently as the N concentration in mature seeds increased. The duration of seed filling (estimated by the effective filling period) was not related to mature seed N concentration. Since higher seed N concentration had no effect on the rate or duration of seed dry matter accumulation by individual seeds, the purported negative effect of seed protein levels on yield may be more closely associated with whole plant phenomena than those operating at the individual seed level.

Grazing management strategies for massaigrass-forage peanut pastures: 2. productivity, utilization and sward structure

This study was carried out to evaluate the productivity, utilization and sward structure of a mixed massaigrass (Panicum maximum x P. infestum, cv. Massai) and forage peanut (Arachis pintoi Ac 01) pasture, intermittently stocked at three daily herbage allowance levels (9.0, 14.5 and 18.4% of live weight). In each grazing cycle, dry matter (DM) accumulation rates, defoliation intensity (%), grazing depth (%) and grazed horizon (cm) were evaluated. The structure of massaigrass tussocks was characterized in both dry and rainy seasons by measuring its pre-grazing morphological composition and post-grazing height and density (tussocks/m). Pastures submitted to higher herbage allowance (HA) levels showed higher productivity, but were less efficiently utilized. On average, over the experimental period, DM accumulation rates increased linearly from 56.8 to 81.3 kg/ha/day as HA levels increased from 9.0 to 18.4% of live weight. However, defoliation intensity and grazing depth declined linearly with increasing HA levels. During the dry season, pre-grazing morphological composition of massaigrass was characterized by 41% of green leaf blades, 10% of pseudostems and 49% of dead material, irrespective of HA levels. In the rainy season, however, it showed higher percentage of green leaf blades and lower percentage of pseudostems when submitted to lower HA levels, although there were not differences in relation to percentage of dead material. The structure of massaigrass tussocks tended to deteriorate at high HA levels.

Morfogênese e acúmulo de forragem em pastagem de Cynodon dactylon cv. coastcross em diferentes estações de crescimento

O experimento foi realizado para se estimar as características morfogênicas e estruturais e a taxa de acúmulo de matéria seca (MS) de lâminas foliares em uma pastagem de Cynodon dactylon cv. coastcross, manejada em sistema de lotação rotacionada com vacas em lactação. As avaliações foram realizadas na primavera (outubro-novembro), no verão (fevereiro-março) e no outono (maio-junho). O estudo foi conduzido em delineamento de casualização completa, com seis repetições. Durante o período de descanso do piquete, os perfilhos do capim foram identificados para observações e registros de alongamento, aparecimento e senescência foliares. Foram contados perfilhos em área de 0,09 m², para estimativa da densidade populacional. A taxa de acúmulo líquido de MS de lâminas foliares/área foi obtida multiplicando-se o acúmulo de MS/perfilho pelo número de perfilhos/área. A taxa de alongamento foliar foi mais alta no verão, enquanto a taxa de aparecimento foliar e o número de folhas/perfilho foram mais elevados na primavera. O número de perfilhos não variou com a estação, apresentando valor médio de 2.770/m². A taxa de senescência foi, em média, de 2,44 mm/dia na primavera, não havendo senescência de folhas durante o verão e o outono. A taxa de acúmulo de MS de lâminas foliares foi mais alta no verão e apresentou estreita relação com a taxa de alongamento e com o tamanho da folha. O uso da taxa de alongamento foliar e da densidade de perfilhos para obtenção das taxas de acúmulo de MS de lâminas foliares/ha superestimou os valores.

Irrigation and Nutrient Effects on Growth and Water–Yield Relationship of Wheat (Triticum aestivum L.) in Central India

AbstractIncreasing production of wheat from a limited water supply can result from efficient irrigation and nutrient management. A 3‐year field experiment was conducted at the Indian Institute of Soil Science, Bhopal, to study the growth, yield, seasonal evapotranspiration (ET) and water use efficiency (WUE), and the water–yield relationship of wheat in a soybean–wheat cropping system on vertisols. Three levels of irrigation, viz. I0, no post‐sowing irrigation; I1, two irrigations [crown root initiation (CRI) and flowering stage]; and I2, three irrigations (CRI, maximum tillering and flowering stage) and three nutrient management treatments, viz. F0, control (without fertilizer/manure); F1, 100 % NPK (100–21.5–24.9 kg ha−1); and F2, 100 % NPK + farmyard manure (FYM‐10 t ha−1) were tested in a split‐plot design with three replication. It has been established (through anova) that the year effect was rather negligible and the interaction effects of irrigation and nutrient management on the growth parameters, ET, yield components, yield and WUE were significant. Plant height, progressive leaf area index, dry matter accumulation and crop growth rate were higher in I2F2, and I2F1 and I1F2 were statistically at par. The seasonal ET increased significantly with the increase in water supply in every nutrient treatment and it was highest in I2F2 and lowest in I0F0. The highest grain yield was obtained in I2F2; and a similar yield was recorded in I3F1 and I2F2. This shows a strong interaction effect between irrigation and nutrients. Yield components, viz. number of ears m−2, number of grains ear−1 and 1000‐grain weight were significant. The higher number of ears m−2 containing greater number of grains with relatively heavier weights appeared to have contributed to the higher yield in I1F2, I2F1 and I2F2. The highest WUE obtained in I0F2 did not correspond to the highest yield and maximum ET, but a WUE of 10.43 kg ha−1 mm−1 in the I2F2 combination corresponded with the highest yield and the seasonal ET requirement was 391.8, which was 137 % greater than the water use at maximum WUE. The ET–grain yield relationship was linear, with a lowest regression slope (i.e. marginal WUE) and elasticity of water production (Ewp) in F0 and a considerably higher slope and Ewp in F1 and F2. As the Ewp is positive and close to one in 100 % NPK treatment, the scope of improving WUE and yield with only inorganic fertilizer is very little, and relatively greater scope exists in the integrated management of organic manure and inorganic fertilizer. The results suggest that integrated nutrient management (100 % NPK + FYM) in conjunction with three irrigations maximized yield of wheat with concomitant improvement in ET and WUE under limited water availability.

Effect of dates of sowing on dry matter production and partitioning in yam bean (Pachyrrhizus erosus (L) Urban)

Climatic factors like temperature, relative humidity, rainfall, day length, and soil edaphic factors influence the growth and yield of a crop. The rate of dry matter accumulation remains faster at higher than lower temperature. However, high temperatures decrease the proportion of dry matter translocated to the tuber. Hence a field experiment was conducted in 1995 to 1996 at the Regional Centre of Central Tuber Crops Research Institute, Bhubaneswar to study the effect of climatic factors on dry matter production and partitioning in yam bean (Pachyrritizits erosus (L) Urban). The results revealed no genotypic differences in dry matter production and yield, indicating that all genotypes used were equally efficient in dry matter production and partitioning, However, date of sowing has marked influence on dry mater production and yield. Sowing on the 17th of August led to the production of higher dry matter with the highest tuber yield comparable with those sown on the 1st of September because of their higher partitioning efficiency. Although the partitioning efficiencies of the October 1st and September 16th sowings were higher, these resulted in lower yield due to lack of sufficient dry matter. These findings clearly indicated that early sowing between the 17th of August and the 1st of September is essential for higher tuber yield in fertile acid laterite soil.