Plant Dry Weight Ratio Research Articles

QTL-seq for rapid identification of candidate genes for 100-seed weight and root/total plant dry weight ratio under rainfed conditions in chickpea.

SummaryTerminal drought is a major constraint to chickpea productivity. Two component traits responsible for reduction in yield under drought stress include reduction in seeds size and root length/root density. QTL‐seq approach, therefore, was used to identify candidate genomic regions for 100‐seed weight (100SDW) and total dry root weight to total plant dry weight ratio (RTR) under rainfed conditions. Genomewide SNP profiling of extreme phenotypic bulks from the ICC 4958 × ICC 1882 population identified two significant genomic regions, one on CaLG01 (1.08 Mb) and another on CaLG04 (2.7 Mb) linkage groups for 100SDW. Similarly, one significant genomic region on CaLG04 (1.10 Mb) was identified for RTR. Comprehensive analysis revealed four and five putative candidate genes associated with 100SDW and RTR, respectively. Subsequently, two genes (Ca_04364 and Ca_04607) for 100SDW and one gene (Ca_04586) for RTR were validated using CAPS/dCAPS markers. Identified candidate genomic regions and genes may be useful for molecular breeding for chickpea improvement.

THE EFFECTS OF N CONCENTRATION IN PRE-TRANSPLANT NUTRIENT SOLUTION ON THE N USE EFFICIENCY AND DRY MASS PARTITIONING OF VEGETABLE SOLANACEAE SEEDLINGS

ISHS IV Balkan Symposium on Vegetables and Potatoes THE EFFECTS OF N CONCENTRATION IN PRE-TRANSPLANT NUTRIENT SOLUTION ON THE N USE EFFICIENCY AND DRY MASS PARTITIONING OF VEGETABLE SOLANACEAE SEEDLINGS

THE INFLUENCE OF DIFFERENT SUBSTRATE COMPOSITION ON GROWTH PARAMETERS AND DRY MASS PARTITIONING OF CUCUMBER (CUCUMIS SATIVUM L.) SEEDLINGS

The influences of substrate composition on growth parameters and dry mass portioning of cucumber (Cucumis sativum L.) seedlings were estimated in an experiment conducted in a plastic greenhouse. Graded seeds of cv. Ekron F1, were individually seeded in foam trays filled with different substrates, namely peat compost (Klassmann product), vermin compost (locally produced) and a mixture (50 % to 50%) of peat compost and vermin compost. Plants were equally irrigated, but no additional nutrient elements were supplied during the experiment time. Roots, stems and leaf dry matter were weighted and stem length and plant leaf area was successfully measured after the first and the second true leafs were appeared. Based on that data, the relative growth rates (RGR) and its components; net assimilation rate (NAR) and leaf area ratio (LAR) were computed. The relative stem elongation rate (RSER), the relative leaf expansion rate (RLER), root to whole plant dry weight ratio (RWR), root to shoot dry weight ratio (RSR), and the respective fractions of roots, stems and leaf dry mass against total plant weight (RMF, SMF, LMF) were also calculated for each experimental plot. A significantly higher relative growth rate (RGR) was found for young seedlings grown in vermin compost compared to commercial peat compost. Though there was a difference on net assimilation rate (the physiological component of RGR), the increased growth rate was mostly due to differences found for leaf assimilation ratio (the morphological component of RGR). Higher dry matter per plant, higher relative stem elongation rate and higher relative leaf expansion rate were found for vermin compost, but no effect was found regarding dry mass partitioning of young cucumber seedlings.

A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae)

Cannabinoids are important chemotaxonomic markers unique to Cannabis. Previous studies show that a plant's dry-weight ratio of Δ(9)-tetrahydrocannabinol (THC) to cannabidiol (CBD) can be assigned to one of three chemotypes and that alleles B(D) and B(T) encode alloenzymes that catalyze the conversion of cannabigerol to CBD and THC, respectively. In the present study, the frequencies of B(D) and B(T) in sample populations of 157 Cannabis accessions were determined from CBD and THC banding patterns, visualized by starch gel electrophoresis. Gas chromatography was used to quantify cannabinoid levels in 96 of the same accessions. The data were interpreted with respect to previous analyses of genetic and morphological variation in the same germplasm collection. Two biotypes (infraspecific taxa of unassigned rank) of C. sativa and four biotypes of C. indica were recognized. Mean THC levels and the frequency of B(T) were significantly higher in C. indica than C. sativa. The proportion of high THC/CBD chemotype plants in most accessions assigned to C. sativa was <25% and in most accessions assigned to C. indica was >25%. Plants with relatively high levels of tetrahydrocannabivarin (THCV) and/or cannabidivarin (CBDV) were common only in C. indica. This study supports a two-species concept of Cannabis.

Effect of fruit load on the water balance of melon plants infected with Monosporascus cannonballus

The effect of Monosporascus cannonballus infection and fruit load on water balance in melon was studied under field conditions in naturally infested soil. Plant water uptake started to decrease shortly before plant wilting and death. Xylem hydraulic conductance of excised infected roots, measured at the onset of wilting, was five to seven times lower than that of healthy plants. An extensive rise in tylose formation was observed in xylem vessels and most vessels were plugged. Plant collapse and death usually occurred during the fruit maturation period. Fruit removal from infected plants prevented wilting, but did not prevent tylose formation and the associated increase in the root resistance to water flow. Continued removal of fruits increased the root plant dry weight ratio in both infected and non-infected plants, 3.5- and 5.8-fold, respectively. Infected plants, showing reversible wilt symptoms and from which fruits were removed, regained leaf turgor and remained alive. Fruit removal caused an immediate and sharp drop in leaf stomatal conductance in both healthy and infected melon plants. The largest reduction was observed after complete fruit removal, compared to plants with one or four to five fruits. Fruit removal also reduced the rate of leaf CO2 assimilation and leaf internal CO2 concentration. Removal of 70–85% of the leaf surface in infected plants did not alter disease progress, relative to control infected plants. The presence of fruits in M. cannonballus -infected plants apparently subjects the plants to progressive water stress till they die. Fruit removal reduced leaf stomatal conductance and increased root growth, thus enabling the plants to survive the constraint to water uptake and translocation imposed by the pathogen, through root destruction, tylose formation and root function.

Influence of Vesicular-Arbuscular Mycorrhizal Fungi on the Response of Potato to Phosphorus Deficiency.

Morphological and biochemical interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus (Glomus fasciculatum [Thaxt. sensu Gerdemann] Gerdemann and Trappe) and potato (Solanum tuberosum L.) plants during the development of P deficiency were characterized. Nonmycorrhizal (NM) plants grown for 63 d with low abiotic P supply (0.5 mM) produced 34, 52, and 73% less root, shoot, and tuber dry matter, respectively, than plants grown with high P (2.5 mM). The total leaf area and the leaf area:plant dry weight ratio of low-P plants were substantially lower than those of high-P plants. Moreover, a lower shoot:root dry weight ratio and tuber:plant dry weight ratio in low-P plants than in high-P plants characterized a major effect of P deficiency stress on dry matter partitioning. In addition to a slower rate of growth, low-P plants accumulated nonreducing sugars and nitrate. Furthermore, root respiration and leaf nitrate reductase activity were lower in low-P plants than in high-P plants. Low abiotic P supply also induced physiological changes that contributed to the greater efficiency of P acquisition by low-P plants than by high-P plants. For example, allocation of dry matter and P to root growth was less restricted by P deficiency stress than to shoot and tuber growth. Also, the specific activities of root acid phosphatases and vanadate-sensitive microsomal ATPases were enhanced in P-deficient plants. The establishment of a VAM symbiosis by low-P plants was essential for efficient P acquisition, and a greater root infection level for P-stressed plants indicated increased compatibility to the VAM fungus. By 63 d after planting, low-P VAM plants had recovered 42% more of the available soil P than low-P NM plants. However, the VAM fungus only partially alleviated P deficiency stress and did not completely compensate for inadequate abiotic P supply. Although the specific activities of acid phosphatases and microsomal ATPases were only marginally influenced by VAM infection, VAM roots characteristically had a higher protein concentration and, consequently, enhanced microsomal ATPase and acid phosphatase activities on a fresh weight basis compared with NM roots. Morphological and ultrastructural details of VAM plants are discussed in relation to the influence of the VAM symbiosis on P nutrition of potato.

VEGETABLE AND GRAIN AMARANTH SEED YIELD AND QUALITY AFFECTED BY APPLIED NITROGEN

Twenty-one day old seedlings of a vegetable amaranth (RCC 241, Amaranthus tricolor) and a grain amaranth (K343, A. hybridus × A. hvpocondriacus) were transplanted on July 28, 1989. Equal applications of NH4N O3 were made on July 28 and August 25 to give total N rates of 0, 60, 120 and 240 kg/ha. Accessions were harvested on Oct. 18 and 14, respectively. Increasing N, induced a quadratic response in plant dry wt, seed wt/plant and seed size fractions in both amaranth types. Seed size fractions as a percent of the total seed, plant height and seed to plant dry weight ratio were not affected by increased N. Seed protein increased linearly whereas seed nitrate increased quadratically with increasing N application. Higher N rates increased residual soil NO3, NR4 and electrolytes and decreased pH. Decreasing soil pH appeared to reduce soil K and Cu but increase Fe and Mn availability. The effect of N rate on seed germination was inconclusive, but the larger seed size was higher in germination. There were differences among species in most responses tested. These data suggest that N applications be tailored to the season growing length required by the respective species/cultivar.

VEGETABLE AND GRAIN AMARANTH SEED YIELD AND QUALITY AFFECTED BY APPLIED NITROGEN

Twenty-one day old seedlings of a vegetable amaranth (RCC 241, Amaranthus tricolor) and a grain amaranth (K343, A. hybridus × A. hvpocondriacus) were transplanted on July 28, 1989. Equal applications of NH4N O3 were made on July 28 and August 25 to give total N rates of 0, 60, 120 and 240 kg/ha. Accessions were harvested on Oct. 18 and 14, respectively. Increasing N, induced a quadratic response in plant dry wt, seed wt/plant and seed size fractions in both amaranth types. Seed size fractions as a percent of the total seed, plant height and seed to plant dry weight ratio were not affected by increased N. Seed protein increased linearly whereas seed nitrate increased quadratically with increasing N application. Higher N rates increased residual soil NO3, NR4 and electrolytes and decreased pH. Decreasing soil pH appeared to reduce soil K and Cu but increase Fe and Mn availability. The effect of N rate on seed germination was inconclusive, but the larger seed size was higher in germination. There were differences among species in most responses tested. These data suggest that N applications be tailored to the season growing length required by the respective species/cultivar.

Root Growth and Dry Matter Distribution of Soybean as Affected by Phosphorus Stress, Nodulation, and Nitrogen Source1

In the field, plant root development is of primary importance under P deficient conditions. Two sand culture experiments were conducted to examine the effects of P stress, nodulation, and N source on the growth, dry matter distribution, and root development of ‘Clark 63’ soybean (Glycine max L. Merr.). In both experiments two levels of N (0 and 5.0 mM N) were employed: plants were either solely dependent upon symbiotic N fixation (N‐fixing), or primarily dependent upon uptake of combined N from the nutrient solution (N supplied). Nodule dry weight of N‐fixing plants grown at the highest P level (2.0 µ/ml) comprised 9% of total plant dry weight and 61% of root dry weight of 35‐day‐old soybeans. A decrease in the P supply inhibited nodule growth relatively more than either root or shoot growth. For N‐supplied soybean, a decrease in the P supply affected shoot growth relatively more than either nodule or root growth. When grown at intermediate P levels (0.02 to 0.5 µ/ml), the root + nodule:total plant dry weight ratio was similar in both N‐fixing and N‐supplied plants. However, the rootttotal plant dry weight ratio of N‐fixing plants was was less than that of N‐supplied plants at all P levels. There was an inverse relationship between nodule mass and total root length although the number of first‐order lateral roots on nodulated and nonnodulated plants was the same.The data suggest that two functional equilibria operate in the N‐fixing plant, namely, the partitioning of dry matter between (i) the underground portion of the plant and the shoot and (ii) the root and nodules. Phosphorus stress affected the root‐nodule equilibrium relatively more than the partitioning of dry matter between below‐ground and above‐ground parts of the plant.