‘Keystone Resistant Giant’ pepper plants, grown at a population of 48,000/ha, were sampled, fractionated, dried, weighed and analyzed for macroelement content every 14 days between 28 and 112 days after transplanting. The highest specific accumulation rate for N, P, K, Ca and Mg occurred 28 to 42 days after transplanting, but the highest absolute nutrient uptake rate was during 56 to 70 days after transplanting, a period when fruit growth was rapid. N, P and K accumulated in leaves-plus-petioles, stems and fruit whereas Ca and Mg were abundant in leaves-plus-petioles but was quite low in fruit tissue. By 98 days after transplanting, the plants had absorbed the following amounts of nutrients in kg/ha: 118 N, 15 P, 123 K, 41 Ca, and 32 Mg. Total dry matter was 4758 kg/ha at the same time. Leaf efficiency as measured by mean net assimilation rate was high during fruit set and growth but declined after commercial harvest. A relatively low leaf area index and a correspondingly high mean net assimilation rate suggested that increased plant populations would result in increased efficiency. There were 114,500 marketable fruits/ha picked during 2 harvests which weighed 13.4 MT.
Two groups of peppers, cv. Yolo Wonder, were cultivated and examined during their vegetative growth period, 1 group in full sun, the other in shade. An analysis of early foliation was initiated following appearance of 3 leaves characteristic of the juvenile growth stage. Observation of the epiderm is indicated that shading increases leaf surface, increases cell division, and cell expansion. Shade decreases the number of stomata per mm2 and the percentage of stomata in relation to other cells. Shade also increases by more than 40% the overall wt of dry materials. After flowering, the 2 lots were transplanted under identical conditions to open fields. Analysis of their fruit yield confirms recommendation of shading during the vegetative growth period in tropical regions.
By various pinching, pruning and grafting experiments and by growing explant buds in nutrient culture, it was demonstrated that buds of varying nodes on the main stem of pepper plants differ in their readiness to flower. The upper ones, in proximity to the 1st branch-off, regardless of whether the 1st flower has actually appeared or is only about to do so, are close to flowering; whereas, the lower ones, situated farther from the first flower, are late to flower. The lowest buds are also the most juvenile and root easily. The state of juvenility decreases gradually towards the apex.
The role of mycorrhiza fungi during acclimatization and post-acclimatization of micropropagated chile ancho plantlets was characterized through physiological and plantlet development changes. Regardless of mycorrhizal colonization, the pepper plantlets had initially low photosynthetic rates and poor growth following transplanting ex vitro. During the first days of acclimatization, water deficits occurred as evidenced by drastic reductions in relative water content. Consequently, transpiration rates and stomatal conductance (gs) declined, confirming that in vitro formed stomata were functional, thus avoiding excessive leaf dehydration and plant death. Mycorrhiza had a positive effect on gas exchange as early as day 7 and 8, as indicated by increasing photosynthesis (A) and gs. Mycorrhizal plantlets had reduced levels of abscisic acid (ABA) during peak stress (6 days after transplanting ex vitro), which corresponded with subsequent increases in gs and A. During acclimatization, A increased in both non-colonized and colonized plantlets, with greater rates observed in mycorrhizal plantlets. During post-acclimatization, mycorrhiza colonized 45% of the roots of pepper plantlets and enhanced plant growth by increasing leaf area, leaf dry mass, and fruit number. Mycorrhiza also enhanced total leaf chlorophyll content, A, and nutrient uptake of pepper plantlets, particularly N, P, and K. Early mycorrhizal colonization produced important benefits, which helped ex vitro transplanted plantlets recover during acclimatization and enhance physiological performance and growth during post-acclimatization.
Pepper seedlings can be infested with broad mites prior to transplanting. Transplanted seedlings may not present visible mite damage symptoms and few microscopic mites will be undetected by growers. A rapid increase of the mite population can subsequently result in yield losses in greenhouse-grown crops. Control of broad mites based on biological (N. californicus) and conventional (sulfur) methods were evaluated after infested transplants were introduced into a production greenhouse. Seedlings were artificially infested with two broad mites, 3 days before they were transplanted in mid-September in a passively ventilated greenhouse in Florida. Plants had either two predatory mites released once [4 days after transplanting (DAT)], or twice (4 and 22 DAT), or were sprayed with sulfur (four weekly applications starting 13 DAT when first damage symptoms were noticed). Damage on plants was assessed by an injury scale transformed into percentage values, with 100% being total damage on untreated infested plants. Broad mites were absent in all plants 38 DAT but the damage caused to the plants at this time was negatively correlated (r= –0.95) with marketable yield at 90 DAT. Plants produced no marketable yield where broad mites were not controlled. One or two releases of predators led to respective damages of 56% and 45%, and fruit yields of 2.0 and 3.0 kg·m-2. Plants sprayed with sulfur had a damage of 7% after reaching a maximum of 74% at 18 DAT; however, yields were 4.3 kg·m-2, which was similar to the yield obtained in the uninfested control treatment (4.6 kg·m-2). Releases of predators prior to transplanting and/or higher predator release densities may be needed under similar conditions and will be evaluated in a subsequent experiment.
The pathogen Phytophthora capsici Leon. is known to be a limiting factor of chile pepper (Capsicum L.) production around the world. The genetics of the resistance is becoming better understood due to the specific nature of the host-pathogen interaction, i.e., all plant organs are subject to infection. It has been shown that phytophthora root rot resistance and phytophthora foliar blight resistance are under different genetic mechanisms. This study aimed at understanding the inheritance of resistance of phytophthora stem blight and to determine whether phytophthora stem blight was the same disease syndrome as phytophthora root rot and phytophthora foliar blight. Stem cuttings of a segregating F2 population and testcross progeny facilitated the ability to screen for two disease syndromes concurrently. When the three disease syndromes were compared separately, the F2 populations fit a 3 resistant (R): 1 susceptible (S) ratio and the testcross progenies fit a 1R:1S ratio. When comparative studies were performed (stem vs. foliar and stem vs. root), the F2 populations fit a 9R/R:3R/S:3S/R:1S/S ratio and the testcross fit a 1R/R:1R/S:1S/R:1S/S ratio. These ratios are consistent of a single gene controlling the resistance of each system. Therefore, phytophthora stem blight, root rot, and foliar blight are three separate disease syndromes.
( Table 1 ). This included six Capsicum species: C. annuum , C. baccatum , C. chinense , C. frutescens , C. chacoense Hunz., and C. rhomboideum (Dunal) Kuntze. Table 1. List of Capsicum accessions evaluated for powdery mildew ( Leveillula
In Capsicum, 39 species have been identified including five domesticated species, C. annuum , C. baccatum , C. chinense, Capsicum frutescens , and Capsicum pubescens ( Carrizo García et al., 2016 ). Chile peppers are an important culinary
to develop varieties of Capsicum for higher yields of red pigmentation need to also breed in a non-pungent or mild Capsicum background ( Hornero-Méndez et al., 2002 ; Walker et al., 2004 ). In New Mexico, the economic value of a chile ( C. annuum
, and electrolyte leakage of fresh-cut pepper slices from large-fruited Capsicum annuum accessions with bell, paprika, pimento, and large elongated pod types (Class 1); small-fruited C. annuum accessions with jalapeno, serrano, and cherry pod types